viewport_lib/resources/
extra_impls.rs

1use super::*;
2
3pub(super) fn generate_edge_indices(triangle_indices: &[u32]) -> Vec<u32> {
4    use std::collections::HashSet;
5    let mut edges: HashSet<(u32, u32)> = HashSet::new();
6    let mut result = Vec::new();
7
8    for tri in triangle_indices.chunks(3) {
9        if tri.len() < 3 {
10            continue;
11        }
12        let pairs = [(tri[0], tri[1]), (tri[1], tri[2]), (tri[2], tri[0])];
13        for (a, b) in &pairs {
14            // Canonical form: smaller index first, so (a,b) and (b,a) map to the same edge.
15            let edge = if a < b { (*a, *b) } else { (*b, *a) };
16            if edges.insert(edge) {
17                result.push(*a);
18                result.push(*b);
19            }
20        }
21    }
22    result
23}
24
25// ---------------------------------------------------------------------------
26// Procedural unit cube mesh (24 vertices, 4 per face, 36 indices)
27// ---------------------------------------------------------------------------
28
29/// Generate a unit cube centered at the origin.
30///
31/// 24 vertices (4 per face with shared normals), 36 indices (2 triangles per face).
32/// All vertices are white [1,1,1,1].
33pub(super) fn build_unit_cube() -> (Vec<Vertex>, Vec<u32>) {
34    let white = [1.0f32, 1.0, 1.0, 1.0];
35    let mut verts: Vec<Vertex> = Vec::with_capacity(24);
36    let mut idx: Vec<u32> = Vec::with_capacity(36);
37
38    // Helper: add a face quad (4 vertices in CCW order) and its 2 triangles.
39    let mut add_face = |positions: [[f32; 3]; 4], normal: [f32; 3]| {
40        let base = verts.len() as u32;
41        for pos in &positions {
42            verts.push(Vertex {
43                position: *pos,
44                normal,
45                colour: white,
46                uv: [0.0, 0.0],
47                tangent: [0.0, 0.0, 0.0, 1.0],
48            });
49        }
50        // Two triangles: (base, base+1, base+2) and (base, base+2, base+3)
51        idx.extend_from_slice(&[base, base + 1, base + 2, base, base + 2, base + 3]);
52    };
53
54    // +X face (right), normal [1, 0, 0]
55    add_face(
56        [
57            [0.5, -0.5, -0.5],
58            [0.5, 0.5, -0.5],
59            [0.5, 0.5, 0.5],
60            [0.5, -0.5, 0.5],
61        ],
62        [1.0, 0.0, 0.0],
63    );
64
65    // -X face (left), normal [-1, 0, 0]
66    add_face(
67        [
68            [-0.5, -0.5, 0.5],
69            [-0.5, 0.5, 0.5],
70            [-0.5, 0.5, -0.5],
71            [-0.5, -0.5, -0.5],
72        ],
73        [-1.0, 0.0, 0.0],
74    );
75
76    // +Y face (top), normal [0, 1, 0]
77    add_face(
78        [
79            [-0.5, 0.5, -0.5],
80            [-0.5, 0.5, 0.5],
81            [0.5, 0.5, 0.5],
82            [0.5, 0.5, -0.5],
83        ],
84        [0.0, 1.0, 0.0],
85    );
86
87    // -Y face (bottom), normal [0, -1, 0]
88    add_face(
89        [
90            [-0.5, -0.5, 0.5],
91            [-0.5, -0.5, -0.5],
92            [0.5, -0.5, -0.5],
93            [0.5, -0.5, 0.5],
94        ],
95        [0.0, -1.0, 0.0],
96    );
97
98    // +Z face (front), normal [0, 0, 1]
99    add_face(
100        [
101            [-0.5, -0.5, 0.5],
102            [0.5, -0.5, 0.5],
103            [0.5, 0.5, 0.5],
104            [-0.5, 0.5, 0.5],
105        ],
106        [0.0, 0.0, 1.0],
107    );
108
109    // -Z face (back), normal [0, 0, -1]
110    add_face(
111        [
112            [0.5, -0.5, -0.5],
113            [-0.5, -0.5, -0.5],
114            [-0.5, 0.5, -0.5],
115            [0.5, 0.5, -0.5],
116        ],
117        [0.0, 0.0, -1.0],
118    );
119
120    (verts, idx)
121}
122
123// ---------------------------------------------------------------------------
124// Procedural glyph arrow mesh (cone tip + cylinder shaft, local +Y axis)
125// ---------------------------------------------------------------------------
126
127/// Generate a unit arrow mesh aligned to local +Y.
128///
129/// The arrow consists of:
130/// - A cylinder shaft from Y=0 to Y=0.7, radius 0.05.
131/// - A cone tip from Y=0.7 to Y=1.0, base radius 0.12.
132///
133/// 16 segments around the circumference gives ~300 vertices.
134pub(super) fn build_glyph_arrow() -> (Vec<Vertex>, Vec<u32>) {
135    let white = [1.0f32, 1.0, 1.0, 1.0];
136    let segments = 16usize;
137    let mut verts: Vec<Vertex> = Vec::new();
138    let mut idx: Vec<u32> = Vec::new();
139
140    let shaft_r = 0.05f32;
141    let shaft_bot = 0.0f32;
142    let shaft_top = 0.7f32;
143    let cone_r = 0.12f32;
144    let cone_bot = shaft_top;
145    let cone_tip = 1.0f32;
146
147    // Helper: append ring vertices at a given Y and radius with outward normals.
148    let ring_verts = |verts: &mut Vec<Vertex>, y: f32, r: f32, normal_y: f32| {
149        for i in 0..segments {
150            let angle = 2.0 * std::f32::consts::PI * (i as f32) / (segments as f32);
151            let (s, c) = angle.sin_cos();
152            let nx = if r > 0.0 { c } else { 0.0 };
153            let nz = if r > 0.0 { s } else { 0.0 };
154            let len = (nx * nx + normal_y * normal_y + nz * nz).sqrt();
155            verts.push(Vertex {
156                position: [c * r, y, s * r],
157                normal: [nx / len, normal_y / len, nz / len],
158                colour: white,
159                uv: [0.0, 0.0],
160                tangent: [0.0, 0.0, 0.0, 1.0],
161            });
162        }
163    };
164
165    // --- Shaft ---
166    // Bottom ring (face down for the cap).
167    let shaft_bot_base = verts.len() as u32;
168    ring_verts(&mut verts, shaft_bot, shaft_r, 0.0);
169
170    // Bottom cap center.
171    let shaft_bot_center = verts.len() as u32;
172    verts.push(Vertex {
173        position: [0.0, shaft_bot, 0.0],
174        normal: [0.0, -1.0, 0.0],
175        colour: white,
176        uv: [0.0, 0.0],
177        tangent: [0.0, 0.0, 0.0, 1.0],
178    });
179
180    // Bottom cap triangles.
181    for i in 0..segments {
182        let a = shaft_bot_base + i as u32;
183        let b = shaft_bot_base + ((i + 1) % segments) as u32;
184        idx.extend_from_slice(&[shaft_bot_center, b, a]);
185    }
186
187    // Side quads: two rings of shaft.
188    let shaft_top_ring_base = verts.len() as u32;
189    ring_verts(&mut verts, shaft_bot, shaft_r, 0.0); // duplicate bottom ring for side normals
190    let shaft_top_ring_top = verts.len() as u32;
191    ring_verts(&mut verts, shaft_top, shaft_r, 0.0);
192    for i in 0..segments {
193        let a = shaft_top_ring_base + i as u32;
194        let b = shaft_top_ring_base + ((i + 1) % segments) as u32;
195        let c = shaft_top_ring_top + i as u32;
196        let d = shaft_top_ring_top + ((i + 1) % segments) as u32;
197        idx.extend_from_slice(&[a, b, d, a, d, c]);
198    }
199
200    // --- Cone ---
201    // Slanted normal angle for cone surface: rise=(cone_tip-cone_bot), run=cone_r.
202    let cone_len = ((cone_tip - cone_bot).powi(2) + cone_r * cone_r).sqrt();
203    let normal_y_cone = cone_r / cone_len; // outward Y component of slanted normal
204    let normal_r_cone = (cone_tip - cone_bot) / cone_len;
205
206    let cone_base_ring = verts.len() as u32;
207    for i in 0..segments {
208        let angle = 2.0 * std::f32::consts::PI * (i as f32) / (segments as f32);
209        let (s, c) = angle.sin_cos();
210        verts.push(Vertex {
211            position: [c * cone_r, cone_bot, s * cone_r],
212            normal: [c * normal_r_cone, normal_y_cone, s * normal_r_cone],
213            colour: white,
214            uv: [0.0, 0.0],
215            tangent: [0.0, 0.0, 0.0, 1.0],
216        });
217    }
218
219    // Cone tip vertex (normals averaged around tip : just point up).
220    let cone_tip_v = verts.len() as u32;
221    verts.push(Vertex {
222        position: [0.0, cone_tip, 0.0],
223        normal: [0.0, 1.0, 0.0],
224        colour: white,
225        uv: [0.0, 0.0],
226        tangent: [0.0, 0.0, 0.0, 1.0],
227    });
228
229    for i in 0..segments {
230        let a = cone_base_ring + i as u32;
231        let b = cone_base_ring + ((i + 1) % segments) as u32;
232        idx.extend_from_slice(&[a, b, cone_tip_v]);
233    }
234
235    // Cone base cap (flat, faces -Y).
236    let cone_cap_base = verts.len() as u32;
237    for i in 0..segments {
238        let angle = 2.0 * std::f32::consts::PI * (i as f32) / (segments as f32);
239        let (s, c) = angle.sin_cos();
240        verts.push(Vertex {
241            position: [c * cone_r, cone_bot, s * cone_r],
242            normal: [0.0, -1.0, 0.0],
243            colour: white,
244            uv: [0.0, 0.0],
245            tangent: [0.0, 0.0, 0.0, 1.0],
246        });
247    }
248    let cone_cap_center = verts.len() as u32;
249    verts.push(Vertex {
250        position: [0.0, cone_bot, 0.0],
251        normal: [0.0, -1.0, 0.0],
252        colour: white,
253        uv: [0.0, 0.0],
254        tangent: [0.0, 0.0, 0.0, 1.0],
255    });
256    for i in 0..segments {
257        let a = cone_cap_base + i as u32;
258        let b = cone_cap_base + ((i + 1) % segments) as u32;
259        idx.extend_from_slice(&[cone_cap_center, b, a]);
260    }
261
262    (verts, idx)
263}
264
265// ---------------------------------------------------------------------------
266// Procedural icosphere (2 subdivisions, ~240 triangles)
267// ---------------------------------------------------------------------------
268
269/// Generate a unit sphere as an icosphere with 2 subdivisions.
270///
271/// Starts from a regular icosahedron and subdivides each triangle 2×.
272pub(super) fn build_glyph_sphere() -> (Vec<Vertex>, Vec<u32>) {
273    let white = [1.0f32, 1.0, 1.0, 1.0];
274
275    // Icosahedron constants.
276    let t = (1.0 + 5.0f32.sqrt()) / 2.0;
277
278    // 12 vertices of a regular icosahedron (not yet normalised).
279    let raw_verts = [
280        [-1.0, t, 0.0],
281        [1.0, t, 0.0],
282        [-1.0, -t, 0.0],
283        [1.0, -t, 0.0],
284        [0.0, -1.0, t],
285        [0.0, 1.0, t],
286        [0.0, -1.0, -t],
287        [0.0, 1.0, -t],
288        [t, 0.0, -1.0],
289        [t, 0.0, 1.0],
290        [-t, 0.0, -1.0],
291        [-t, 0.0, 1.0],
292    ];
293
294    let mut positions: Vec<[f32; 3]> = raw_verts
295        .iter()
296        .map(|v| {
297            let l = (v[0] * v[0] + v[1] * v[1] + v[2] * v[2]).sqrt();
298            [v[0] / l, v[1] / l, v[2] / l]
299        })
300        .collect();
301
302    // 20 base triangles.
303    let mut triangles: Vec<[usize; 3]> = vec![
304        [0, 11, 5],
305        [0, 5, 1],
306        [0, 1, 7],
307        [0, 7, 10],
308        [0, 10, 11],
309        [1, 5, 9],
310        [5, 11, 4],
311        [11, 10, 2],
312        [10, 7, 6],
313        [7, 1, 8],
314        [3, 9, 4],
315        [3, 4, 2],
316        [3, 2, 6],
317        [3, 6, 8],
318        [3, 8, 9],
319        [4, 9, 5],
320        [2, 4, 11],
321        [6, 2, 10],
322        [8, 6, 7],
323        [9, 8, 1],
324    ];
325
326    // Subdivide 2 times.
327    for _ in 0..2 {
328        let mut mid_cache: std::collections::HashMap<(usize, usize), usize> =
329            std::collections::HashMap::new();
330        let mut new_triangles: Vec<[usize; 3]> = Vec::with_capacity(triangles.len() * 4);
331
332        let midpoint = |positions: &mut Vec<[f32; 3]>,
333                        a: usize,
334                        b: usize,
335                        cache: &mut std::collections::HashMap<(usize, usize), usize>|
336         -> usize {
337            let key = if a < b { (a, b) } else { (b, a) };
338            if let Some(&idx) = cache.get(&key) {
339                return idx;
340            }
341            let pa = positions[a];
342            let pb = positions[b];
343            let mx = (pa[0] + pb[0]) * 0.5;
344            let my = (pa[1] + pb[1]) * 0.5;
345            let mz = (pa[2] + pb[2]) * 0.5;
346            let l = (mx * mx + my * my + mz * mz).sqrt();
347            let idx = positions.len();
348            positions.push([mx / l, my / l, mz / l]);
349            cache.insert(key, idx);
350            idx
351        };
352
353        for tri in &triangles {
354            let a = tri[0];
355            let b = tri[1];
356            let c = tri[2];
357            let ab = midpoint(&mut positions, a, b, &mut mid_cache);
358            let bc = midpoint(&mut positions, b, c, &mut mid_cache);
359            let ca = midpoint(&mut positions, c, a, &mut mid_cache);
360            new_triangles.push([a, ab, ca]);
361            new_triangles.push([b, bc, ab]);
362            new_triangles.push([c, ca, bc]);
363            new_triangles.push([ab, bc, ca]);
364        }
365        triangles = new_triangles;
366    }
367
368    let verts: Vec<Vertex> = positions
369        .iter()
370        .map(|&p| Vertex {
371            position: p,
372            normal: p, // unit sphere: position = normal
373            colour: white,
374            uv: [0.0, 0.0],
375            tangent: [0.0, 0.0, 0.0, 1.0],
376        })
377        .collect();
378
379    let idx: Vec<u32> = triangles
380        .iter()
381        .flat_map(|t| [t[0] as u32, t[1] as u32, t[2] as u32])
382        .collect();
383
384    (verts, idx)
385}
386
387// ---------------------------------------------------------------------------
388// Attribute interpolation utilities
389// ---------------------------------------------------------------------------
390
391// ---------------------------------------------------------------------------
392// Phase G : in-place attribute hot-swap
393// ---------------------------------------------------------------------------
394
395impl ViewportGpuResources {
396    /// Write new scalar data into an existing attribute buffer in-place.
397    ///
398    /// No GPU buffer reallocation, no mesh re-upload, no bind group rebuild is
399    /// required. The attribute bind group *will* be rebuilt on the next
400    /// `prepare()` call if the scalar range changes (tracked via `last_tex_key`).
401    ///
402    /// # Errors
403    ///
404    /// - [`ViewportError::MeshSlotEmpty`](crate::error::ViewportError::MeshSlotEmpty) : `mesh_id` not found in the store.
405    /// - [`ViewportError::AttributeNotFound`](crate::error::ViewportError::AttributeNotFound) : `name` not present on the mesh.
406    /// - [`ViewportError::AttributeLengthMismatch`](crate::error::ViewportError::AttributeLengthMismatch) : `data.len()` differs from
407    ///   the original upload (same-topology requirement).
408    pub fn replace_attribute(
409        &mut self,
410        queue: &wgpu::Queue,
411        mesh_id: crate::resources::mesh_store::MeshId,
412        name: &str,
413        data: &[f32],
414    ) -> crate::error::ViewportResult<()> {
415        // Resolve the mesh.
416        let gpu_mesh =
417            self.mesh_store
418                .get_mut(mesh_id)
419                .ok_or(crate::error::ViewportError::MeshSlotEmpty {
420                    index: mesh_id.index(),
421                })?;
422
423        // Find the existing attribute buffer.
424        let buffer = gpu_mesh.attribute_buffers.get(name).ok_or_else(|| {
425            crate::error::ViewportError::AttributeNotFound {
426                mesh_id: mesh_id.index(),
427                name: name.to_string(),
428            }
429        })?;
430
431        // Validate same topology (buffer size must match).
432        let expected_elems = (buffer.size() / 4) as usize;
433        if data.len() != expected_elems {
434            return Err(crate::error::ViewportError::AttributeLengthMismatch {
435                expected: expected_elems,
436                got: data.len(),
437            });
438        }
439
440        // Zero-copy in-place write via the wgpu staging belt.
441        queue.write_buffer(buffer, 0, bytemuck::cast_slice(data));
442
443        // Recompute scalar range so LUT mapping stays accurate.
444        let (min, max) = data
445            .iter()
446            .fold((f32::MAX, f32::MIN), |(mn, mx), &v| (mn.min(v), mx.max(v)));
447        let range = if min > max { (0.0, 1.0) } else { (min, max) };
448        gpu_mesh.attribute_ranges.insert(name.to_string(), range);
449
450        // Force bind group rebuild on next prepare() by invalidating the key.
451        gpu_mesh.last_tex_key = (
452            gpu_mesh.last_tex_key.0,
453            gpu_mesh.last_tex_key.1,
454            gpu_mesh.last_tex_key.2,
455            gpu_mesh.last_tex_key.3,
456            u64::MAX, // attribute hash component
457            gpu_mesh.last_tex_key.5,
458            gpu_mesh.last_tex_key.6,
459            gpu_mesh.last_tex_key.7,
460            gpu_mesh.last_tex_key.8,
461        );
462
463        Ok(())
464    }
465
466    /// Create a camera bind group (group 0) for the given per-viewport buffers.
467    ///
468    /// Per-viewport buffers (camera, clip planes, shadow info, clip volume) are
469    /// passed explicitly. Scene-global resources (lights, shadow atlas, IBL) come
470    /// from shared resources on `self`.
471    ///
472    /// NOTE: The initial bind group in `init.rs` is constructed inline (before
473    /// `Self` exists). Keep the binding layout in sync when modifying either site.
474    pub(crate) fn create_camera_bind_group(
475        &self,
476        device: &wgpu::Device,
477        camera_buf: &wgpu::Buffer,
478        clip_planes_buf: &wgpu::Buffer,
479        shadow_info_buf: &wgpu::Buffer,
480        clip_volume_buf: &wgpu::Buffer,
481        label: &str,
482    ) -> wgpu::BindGroup {
483        let irr = self
484            .ibl_irradiance_view
485            .as_ref()
486            .unwrap_or(&self.ibl_fallback_view);
487        let spec = self
488            .ibl_prefiltered_view
489            .as_ref()
490            .unwrap_or(&self.ibl_fallback_view);
491        let brdf = self
492            .ibl_brdf_lut_view
493            .as_ref()
494            .unwrap_or(&self.ibl_fallback_brdf_view);
495        let skybox = self
496            .ibl_skybox_view
497            .as_ref()
498            .unwrap_or(&self.ibl_fallback_view);
499
500        device.create_bind_group(&wgpu::BindGroupDescriptor {
501            label: Some(label),
502            layout: &self.camera_bind_group_layout,
503            entries: &[
504                wgpu::BindGroupEntry {
505                    binding: 0,
506                    resource: camera_buf.as_entire_binding(),
507                },
508                wgpu::BindGroupEntry {
509                    binding: 1,
510                    resource: wgpu::BindingResource::TextureView(&self.shadow_map_view),
511                },
512                wgpu::BindGroupEntry {
513                    binding: 2,
514                    resource: wgpu::BindingResource::Sampler(&self.shadow_sampler),
515                },
516                wgpu::BindGroupEntry {
517                    binding: 3,
518                    resource: self.light_uniform_buf.as_entire_binding(),
519                },
520                wgpu::BindGroupEntry {
521                    binding: 4,
522                    resource: clip_planes_buf.as_entire_binding(),
523                },
524                wgpu::BindGroupEntry {
525                    binding: 5,
526                    resource: shadow_info_buf.as_entire_binding(),
527                },
528                wgpu::BindGroupEntry {
529                    binding: 6,
530                    resource: clip_volume_buf.as_entire_binding(),
531                },
532                wgpu::BindGroupEntry {
533                    binding: 7,
534                    resource: wgpu::BindingResource::TextureView(irr),
535                },
536                wgpu::BindGroupEntry {
537                    binding: 8,
538                    resource: wgpu::BindingResource::TextureView(spec),
539                },
540                wgpu::BindGroupEntry {
541                    binding: 9,
542                    resource: wgpu::BindingResource::TextureView(brdf),
543                },
544                wgpu::BindGroupEntry {
545                    binding: 10,
546                    resource: wgpu::BindingResource::Sampler(&self.ibl_sampler),
547                },
548                wgpu::BindGroupEntry {
549                    binding: 11,
550                    resource: wgpu::BindingResource::TextureView(skybox),
551                },
552            ],
553        })
554    }
555}
556
557// ---------------------------------------------------------------------------
558// Phase G : GPU compute filter pipeline and dispatch
559// ---------------------------------------------------------------------------
560
561/// Output from a single GPU compute filter dispatch.
562///
563/// Contains a compacted index buffer (triangles that passed the filter)
564/// and the count of valid indices. The renderer swaps this in during draw.
565pub struct ComputeFilterResult {
566    /// Output index buffer containing only passing triangles.
567    pub index_buffer: wgpu::Buffer,
568    /// Number of valid indices in `index_buffer` (may be 0 if all filtered).
569    pub index_count: u32,
570    /// `MeshId` this result corresponds to.
571    pub mesh_id: crate::resources::mesh_store::MeshId,
572}
573
574impl ViewportGpuResources {
575    /// Lazily create the GPU compute filter pipeline on first use.
576    fn ensure_compute_filter_pipeline(&mut self, device: &wgpu::Device) {
577        if self.compute_filter_pipeline.is_some() {
578            return;
579        }
580
581        // Build bind group layout.
582        let bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
583            label: Some("compute_filter_bgl"),
584            entries: &[
585                // binding 0: params uniform
586                wgpu::BindGroupLayoutEntry {
587                    binding: 0,
588                    visibility: wgpu::ShaderStages::COMPUTE,
589                    ty: wgpu::BindingType::Buffer {
590                        ty: wgpu::BufferBindingType::Uniform,
591                        has_dynamic_offset: false,
592                        min_binding_size: None,
593                    },
594                    count: None,
595                },
596                // binding 1: vertices (f32 storage, read)
597                wgpu::BindGroupLayoutEntry {
598                    binding: 1,
599                    visibility: wgpu::ShaderStages::COMPUTE,
600                    ty: wgpu::BindingType::Buffer {
601                        ty: wgpu::BufferBindingType::Storage { read_only: true },
602                        has_dynamic_offset: false,
603                        min_binding_size: None,
604                    },
605                    count: None,
606                },
607                // binding 2: source indices (u32 storage, read)
608                wgpu::BindGroupLayoutEntry {
609                    binding: 2,
610                    visibility: wgpu::ShaderStages::COMPUTE,
611                    ty: wgpu::BindingType::Buffer {
612                        ty: wgpu::BufferBindingType::Storage { read_only: true },
613                        has_dynamic_offset: false,
614                        min_binding_size: None,
615                    },
616                    count: None,
617                },
618                // binding 3: scalars (f32 storage, read) : dummy for Clip
619                wgpu::BindGroupLayoutEntry {
620                    binding: 3,
621                    visibility: wgpu::ShaderStages::COMPUTE,
622                    ty: wgpu::BindingType::Buffer {
623                        ty: wgpu::BufferBindingType::Storage { read_only: true },
624                        has_dynamic_offset: false,
625                        min_binding_size: None,
626                    },
627                    count: None,
628                },
629                // binding 4: output compacted indices (read_write)
630                wgpu::BindGroupLayoutEntry {
631                    binding: 4,
632                    visibility: wgpu::ShaderStages::COMPUTE,
633                    ty: wgpu::BindingType::Buffer {
634                        ty: wgpu::BufferBindingType::Storage { read_only: false },
635                        has_dynamic_offset: false,
636                        min_binding_size: None,
637                    },
638                    count: None,
639                },
640                // binding 5: atomic counter (read_write)
641                wgpu::BindGroupLayoutEntry {
642                    binding: 5,
643                    visibility: wgpu::ShaderStages::COMPUTE,
644                    ty: wgpu::BindingType::Buffer {
645                        ty: wgpu::BufferBindingType::Storage { read_only: false },
646                        has_dynamic_offset: false,
647                        min_binding_size: None,
648                    },
649                    count: None,
650                },
651            ],
652        });
653
654        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
655            label: Some("compute_filter_layout"),
656            bind_group_layouts: &[&bgl],
657            push_constant_ranges: &[],
658        });
659
660        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
661            label: Some("compute_filter_shader"),
662            source: wgpu::ShaderSource::Wgsl(include_str!("../shaders/compute_filter.wgsl").into()),
663        });
664
665        let pipeline = device.create_compute_pipeline(&wgpu::ComputePipelineDescriptor {
666            label: Some("compute_filter_pipeline"),
667            layout: Some(&pipeline_layout),
668            module: &shader,
669            entry_point: Some("main"),
670            compilation_options: Default::default(),
671            cache: None,
672        });
673
674        self.compute_filter_bgl = Some(bgl);
675        self.compute_filter_pipeline = Some(pipeline);
676    }
677
678    // -----------------------------------------------------------------------
679    // Phase J: OIT (order-independent transparency) resource management
680    // -----------------------------------------------------------------------
681
682    /// Ensure OIT accum/reveal textures, pipelines, and composite bind group exist
683    /// for the given viewport size.  Call once per frame before the OIT pass.
684    ///
685    /// Early-returns immediately if the size is unchanged and all resources are present.
686    #[allow(dead_code)]
687    pub(crate) fn ensure_oit_targets(&mut self, device: &wgpu::Device, w: u32, h: u32) {
688        let w = w.max(1);
689        let h = h.max(1);
690
691        // Only recreate textures and the composite bind group when size changes.
692        let need_textures = self.oit_size != [w, h] || self.oit_accum_texture.is_none();
693
694        if need_textures {
695            self.oit_size = [w, h];
696
697            // Accum texture: Rgba16Float for accumulation of weighted colour+alpha.
698            let accum_tex = device.create_texture(&wgpu::TextureDescriptor {
699                label: Some("oit_accum_texture"),
700                size: wgpu::Extent3d {
701                    width: w,
702                    height: h,
703                    depth_or_array_layers: 1,
704                },
705                mip_level_count: 1,
706                sample_count: 1,
707                dimension: wgpu::TextureDimension::D2,
708                format: wgpu::TextureFormat::Rgba16Float,
709                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
710                    | wgpu::TextureUsages::TEXTURE_BINDING,
711                view_formats: &[],
712            });
713            let accum_view = accum_tex.create_view(&wgpu::TextureViewDescriptor::default());
714
715            // Reveal texture: R8Unorm for transmittance accumulation.
716            let reveal_tex = device.create_texture(&wgpu::TextureDescriptor {
717                label: Some("oit_reveal_texture"),
718                size: wgpu::Extent3d {
719                    width: w,
720                    height: h,
721                    depth_or_array_layers: 1,
722                },
723                mip_level_count: 1,
724                sample_count: 1,
725                dimension: wgpu::TextureDimension::D2,
726                format: wgpu::TextureFormat::R8Unorm,
727                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
728                    | wgpu::TextureUsages::TEXTURE_BINDING,
729                view_formats: &[],
730            });
731            let reveal_view = reveal_tex.create_view(&wgpu::TextureViewDescriptor::default());
732
733            // Create or reuse the OIT sampler.
734            let sampler = if self.oit_composite_sampler.is_none() {
735                device.create_sampler(&wgpu::SamplerDescriptor {
736                    label: Some("oit_composite_sampler"),
737                    address_mode_u: wgpu::AddressMode::ClampToEdge,
738                    address_mode_v: wgpu::AddressMode::ClampToEdge,
739                    address_mode_w: wgpu::AddressMode::ClampToEdge,
740                    mag_filter: wgpu::FilterMode::Linear,
741                    min_filter: wgpu::FilterMode::Linear,
742                    ..Default::default()
743                })
744            } else {
745                // We can't move out of self here, so create a new one.
746                device.create_sampler(&wgpu::SamplerDescriptor {
747                    label: Some("oit_composite_sampler"),
748                    address_mode_u: wgpu::AddressMode::ClampToEdge,
749                    address_mode_v: wgpu::AddressMode::ClampToEdge,
750                    address_mode_w: wgpu::AddressMode::ClampToEdge,
751                    mag_filter: wgpu::FilterMode::Linear,
752                    min_filter: wgpu::FilterMode::Linear,
753                    ..Default::default()
754                })
755            };
756
757            // Create BGL once.
758            let bgl = if self.oit_composite_bgl.is_none() {
759                let bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
760                    label: Some("oit_composite_bgl"),
761                    entries: &[
762                        wgpu::BindGroupLayoutEntry {
763                            binding: 0,
764                            visibility: wgpu::ShaderStages::FRAGMENT,
765                            ty: wgpu::BindingType::Texture {
766                                sample_type: wgpu::TextureSampleType::Float { filterable: true },
767                                view_dimension: wgpu::TextureViewDimension::D2,
768                                multisampled: false,
769                            },
770                            count: None,
771                        },
772                        wgpu::BindGroupLayoutEntry {
773                            binding: 1,
774                            visibility: wgpu::ShaderStages::FRAGMENT,
775                            ty: wgpu::BindingType::Texture {
776                                sample_type: wgpu::TextureSampleType::Float { filterable: true },
777                                view_dimension: wgpu::TextureViewDimension::D2,
778                                multisampled: false,
779                            },
780                            count: None,
781                        },
782                        wgpu::BindGroupLayoutEntry {
783                            binding: 2,
784                            visibility: wgpu::ShaderStages::FRAGMENT,
785                            ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
786                            count: None,
787                        },
788                    ],
789                });
790                self.oit_composite_bgl = Some(bgl);
791                self.oit_composite_bgl.as_ref().unwrap()
792            } else {
793                self.oit_composite_bgl.as_ref().unwrap()
794            };
795
796            // Composite bind group referencing the new texture views.
797            let composite_bg = device.create_bind_group(&wgpu::BindGroupDescriptor {
798                label: Some("oit_composite_bind_group"),
799                layout: bgl,
800                entries: &[
801                    wgpu::BindGroupEntry {
802                        binding: 0,
803                        resource: wgpu::BindingResource::TextureView(&accum_view),
804                    },
805                    wgpu::BindGroupEntry {
806                        binding: 1,
807                        resource: wgpu::BindingResource::TextureView(&reveal_view),
808                    },
809                    wgpu::BindGroupEntry {
810                        binding: 2,
811                        resource: wgpu::BindingResource::Sampler(&sampler),
812                    },
813                ],
814            });
815
816            self.oit_accum_texture = Some(accum_tex);
817            self.oit_accum_view = Some(accum_view);
818            self.oit_reveal_texture = Some(reveal_tex);
819            self.oit_reveal_view = Some(reveal_view);
820            self.oit_composite_sampler = Some(sampler);
821            self.oit_composite_bind_group = Some(composite_bg);
822        }
823
824        // Create pipelines once (they don't depend on viewport size).
825        if self.oit_pipeline.is_none() {
826            // Non-instanced OIT pipeline (mesh_oit.wgsl, group 0 = camera BGL, group 1 = object BGL).
827            let oit_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
828                label: Some("mesh_oit_shader"),
829                source: wgpu::ShaderSource::Wgsl(include_str!("../shaders/mesh_oit.wgsl").into()),
830            });
831            let oit_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
832                label: Some("oit_pipeline_layout"),
833                bind_group_layouts: &[
834                    &self.camera_bind_group_layout,
835                    &self.object_bind_group_layout,
836                ],
837                push_constant_ranges: &[],
838            });
839
840            // Accum blend: src=One, dst=One, Add (additive accumulation).
841            let accum_blend = wgpu::BlendState {
842                color: wgpu::BlendComponent {
843                    src_factor: wgpu::BlendFactor::One,
844                    dst_factor: wgpu::BlendFactor::One,
845                    operation: wgpu::BlendOperation::Add,
846                },
847                alpha: wgpu::BlendComponent {
848                    src_factor: wgpu::BlendFactor::One,
849                    dst_factor: wgpu::BlendFactor::One,
850                    operation: wgpu::BlendOperation::Add,
851                },
852            };
853
854            // Reveal blend: src=Zero, dst=OneMinusSrcColour (multiplicative transmittance).
855            let reveal_blend = wgpu::BlendState {
856                color: wgpu::BlendComponent {
857                    src_factor: wgpu::BlendFactor::Zero,
858                    dst_factor: wgpu::BlendFactor::OneMinusSrc,
859                    operation: wgpu::BlendOperation::Add,
860                },
861                alpha: wgpu::BlendComponent {
862                    src_factor: wgpu::BlendFactor::Zero,
863                    dst_factor: wgpu::BlendFactor::OneMinusSrc,
864                    operation: wgpu::BlendOperation::Add,
865                },
866            };
867
868            let oit_depth_stencil = wgpu::DepthStencilState {
869                format: wgpu::TextureFormat::Depth24PlusStencil8,
870                depth_write_enabled: false,
871                depth_compare: wgpu::CompareFunction::LessEqual,
872                stencil: wgpu::StencilState::default(),
873                bias: wgpu::DepthBiasState::default(),
874            };
875
876            let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
877                label: Some("oit_pipeline"),
878                layout: Some(&oit_layout),
879                vertex: wgpu::VertexState {
880                    module: &oit_shader,
881                    entry_point: Some("vs_main"),
882                    buffers: &[Vertex::buffer_layout()],
883                    compilation_options: wgpu::PipelineCompilationOptions::default(),
884                },
885                fragment: Some(wgpu::FragmentState {
886                    module: &oit_shader,
887                    entry_point: Some("fs_oit_main"),
888                    targets: &[
889                        Some(wgpu::ColorTargetState {
890                            format: wgpu::TextureFormat::Rgba16Float,
891                            blend: Some(accum_blend),
892                            write_mask: wgpu::ColorWrites::ALL,
893                        }),
894                        Some(wgpu::ColorTargetState {
895                            format: wgpu::TextureFormat::R8Unorm,
896                            blend: Some(reveal_blend),
897                            write_mask: wgpu::ColorWrites::RED,
898                        }),
899                    ],
900                    compilation_options: wgpu::PipelineCompilationOptions::default(),
901                }),
902                primitive: wgpu::PrimitiveState {
903                    topology: wgpu::PrimitiveTopology::TriangleList,
904                    cull_mode: Some(wgpu::Face::Back),
905                    ..Default::default()
906                },
907                depth_stencil: Some(oit_depth_stencil.clone()),
908                multisample: wgpu::MultisampleState {
909                    count: 1,
910                    ..Default::default()
911                },
912                multiview: None,
913                cache: None,
914            });
915            self.oit_pipeline = Some(pipeline);
916
917            // Instanced OIT pipeline (mesh_instanced_oit.wgsl, two OIT targets).
918            if let Some(ref instance_bgl) = self.instance_bind_group_layout {
919                let instanced_oit_shader =
920                    device.create_shader_module(wgpu::ShaderModuleDescriptor {
921                        label: Some("mesh_instanced_oit_shader"),
922                        source: wgpu::ShaderSource::Wgsl(
923                            include_str!("../shaders/mesh_instanced_oit.wgsl").into(),
924                        ),
925                    });
926                let instanced_oit_layout =
927                    device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
928                        label: Some("oit_instanced_pipeline_layout"),
929                        bind_group_layouts: &[&self.camera_bind_group_layout, instance_bgl],
930                        push_constant_ranges: &[],
931                    });
932                let instanced_pipeline =
933                    device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
934                        label: Some("oit_instanced_pipeline"),
935                        layout: Some(&instanced_oit_layout),
936                        vertex: wgpu::VertexState {
937                            module: &instanced_oit_shader,
938                            entry_point: Some("vs_main"),
939                            buffers: &[Vertex::buffer_layout()],
940                            compilation_options: wgpu::PipelineCompilationOptions::default(),
941                        },
942                        fragment: Some(wgpu::FragmentState {
943                            module: &instanced_oit_shader,
944                            entry_point: Some("fs_oit_main"),
945                            targets: &[
946                                Some(wgpu::ColorTargetState {
947                                    format: wgpu::TextureFormat::Rgba16Float,
948                                    blend: Some(accum_blend),
949                                    write_mask: wgpu::ColorWrites::ALL,
950                                }),
951                                Some(wgpu::ColorTargetState {
952                                    format: wgpu::TextureFormat::R8Unorm,
953                                    blend: Some(reveal_blend),
954                                    write_mask: wgpu::ColorWrites::RED,
955                                }),
956                            ],
957                            compilation_options: wgpu::PipelineCompilationOptions::default(),
958                        }),
959                        primitive: wgpu::PrimitiveState {
960                            topology: wgpu::PrimitiveTopology::TriangleList,
961                            cull_mode: Some(wgpu::Face::Back),
962                            ..Default::default()
963                        },
964                        depth_stencil: Some(oit_depth_stencil),
965                        multisample: wgpu::MultisampleState {
966                            count: 1,
967                            ..Default::default()
968                        },
969                        multiview: None,
970                        cache: None,
971                    });
972                self.oit_instanced_pipeline = Some(instanced_pipeline);
973            }
974        }
975
976        if self.oit_composite_pipeline.is_none() {
977            let comp_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
978                label: Some("oit_composite_shader"),
979                source: wgpu::ShaderSource::Wgsl(
980                    include_str!("../shaders/oit_composite.wgsl").into(),
981                ),
982            });
983            let bgl = self
984                .oit_composite_bgl
985                .as_ref()
986                .expect("oit_composite_bgl must exist");
987            let comp_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
988                label: Some("oit_composite_pipeline_layout"),
989                bind_group_layouts: &[bgl],
990                push_constant_ranges: &[],
991            });
992            // Premultiplied alpha blend: One / OneMinusSrcAlpha : composites avg_colour*(1-r) onto HDR.
993            let premul_blend = wgpu::BlendState {
994                color: wgpu::BlendComponent {
995                    src_factor: wgpu::BlendFactor::One,
996                    dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
997                    operation: wgpu::BlendOperation::Add,
998                },
999                alpha: wgpu::BlendComponent {
1000                    src_factor: wgpu::BlendFactor::One,
1001                    dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
1002                    operation: wgpu::BlendOperation::Add,
1003                },
1004            };
1005            let comp_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
1006                label: Some("oit_composite_pipeline"),
1007                layout: Some(&comp_layout),
1008                vertex: wgpu::VertexState {
1009                    module: &comp_shader,
1010                    entry_point: Some("vs_main"),
1011                    buffers: &[],
1012                    compilation_options: wgpu::PipelineCompilationOptions::default(),
1013                },
1014                fragment: Some(wgpu::FragmentState {
1015                    module: &comp_shader,
1016                    entry_point: Some("fs_main"),
1017                    targets: &[Some(wgpu::ColorTargetState {
1018                        format: wgpu::TextureFormat::Rgba16Float,
1019                        blend: Some(premul_blend),
1020                        write_mask: wgpu::ColorWrites::ALL,
1021                    })],
1022                    compilation_options: wgpu::PipelineCompilationOptions::default(),
1023                }),
1024                primitive: wgpu::PrimitiveState {
1025                    topology: wgpu::PrimitiveTopology::TriangleList,
1026                    ..Default::default()
1027                },
1028                depth_stencil: None,
1029                multisample: wgpu::MultisampleState {
1030                    count: 1,
1031                    ..Default::default()
1032                },
1033                multiview: None,
1034                cache: None,
1035            });
1036            self.oit_composite_pipeline = Some(comp_pipeline);
1037        }
1038    }
1039
1040    /// Dispatch GPU compute filters for all items in the list.
1041    ///
1042    /// Returns one [`ComputeFilterResult`] per item. The renderer uses these
1043    /// during `paint()` to override the mesh's default index buffer.
1044    ///
1045    /// This is a synchronous v1 implementation: it submits each dispatch
1046    /// individually and polls the device to read back the counter. This is
1047    /// acceptable for v1; async readback can be added later.
1048    pub fn run_compute_filters(
1049        &mut self,
1050        device: &wgpu::Device,
1051        queue: &wgpu::Queue,
1052        items: &[crate::renderer::ComputeFilterItem],
1053    ) -> Vec<ComputeFilterResult> {
1054        if items.is_empty() {
1055            return Vec::new();
1056        }
1057
1058        self.ensure_compute_filter_pipeline(device);
1059
1060        // Dummy 4-byte buffer used as the scalar binding when doing a Clip filter.
1061        let dummy_scalar_buf = device.create_buffer(&wgpu::BufferDescriptor {
1062            label: Some("compute_filter_dummy_scalar"),
1063            size: 4,
1064            usage: wgpu::BufferUsages::STORAGE,
1065            mapped_at_creation: false,
1066        });
1067
1068        let mut results = Vec::with_capacity(items.len());
1069
1070        for item in items {
1071            // Resolve the mesh.
1072            let gpu_mesh = match self.mesh_store.get(item.mesh_id) {
1073                Some(m) => m,
1074                None => continue,
1075            };
1076
1077            let triangle_count = gpu_mesh.index_count / 3;
1078            if triangle_count == 0 {
1079                continue;
1080            }
1081
1082            // Vertex stride: the Vertex struct is 64 bytes = 16 f32s.
1083            const VERTEX_STRIDE_F32: u32 = 16;
1084
1085            // Build params uniform matching compute_filter.wgsl Params struct layout.
1086            #[repr(C)]
1087            #[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
1088            struct FilterParams {
1089                mode: u32,
1090                clip_type: u32,
1091                threshold_min: f32,
1092                threshold_max: f32,
1093                triangle_count: u32,
1094                vertex_stride_f32: u32,
1095                _pad: [u32; 2],
1096                // Plane params
1097                plane_nx: f32,
1098                plane_ny: f32,
1099                plane_nz: f32,
1100                plane_dist: f32,
1101                // Box params
1102                box_cx: f32,
1103                box_cy: f32,
1104                box_cz: f32,
1105                _padb0: f32,
1106                box_hex: f32,
1107                box_hey: f32,
1108                box_hez: f32,
1109                _padb1: f32,
1110                box_col0x: f32,
1111                box_col0y: f32,
1112                box_col0z: f32,
1113                _padb2: f32,
1114                box_col1x: f32,
1115                box_col1y: f32,
1116                box_col1z: f32,
1117                _padb3: f32,
1118                box_col2x: f32,
1119                box_col2y: f32,
1120                box_col2z: f32,
1121                _padb4: f32,
1122                // Sphere params
1123                sphere_cx: f32,
1124                sphere_cy: f32,
1125                sphere_cz: f32,
1126                sphere_radius: f32,
1127            }
1128
1129            let mut params: FilterParams = bytemuck::Zeroable::zeroed();
1130            params.triangle_count = triangle_count;
1131            params.vertex_stride_f32 = VERTEX_STRIDE_F32;
1132
1133            match item.kind {
1134                crate::renderer::ComputeFilterKind::Clip {
1135                    plane_normal,
1136                    plane_dist,
1137                } => {
1138                    params.mode = 0;
1139                    params.clip_type = 1;
1140                    params.plane_nx = plane_normal[0];
1141                    params.plane_ny = plane_normal[1];
1142                    params.plane_nz = plane_normal[2];
1143                    params.plane_dist = plane_dist;
1144                }
1145                crate::renderer::ComputeFilterKind::ClipBox {
1146                    center,
1147                    half_extents,
1148                    orientation,
1149                } => {
1150                    params.mode = 0;
1151                    params.clip_type = 2;
1152                    params.box_cx = center[0];
1153                    params.box_cy = center[1];
1154                    params.box_cz = center[2];
1155                    params.box_hex = half_extents[0];
1156                    params.box_hey = half_extents[1];
1157                    params.box_hez = half_extents[2];
1158                    params.box_col0x = orientation[0][0];
1159                    params.box_col0y = orientation[0][1];
1160                    params.box_col0z = orientation[0][2];
1161                    params.box_col1x = orientation[1][0];
1162                    params.box_col1y = orientation[1][1];
1163                    params.box_col1z = orientation[1][2];
1164                    params.box_col2x = orientation[2][0];
1165                    params.box_col2y = orientation[2][1];
1166                    params.box_col2z = orientation[2][2];
1167                }
1168                crate::renderer::ComputeFilterKind::ClipSphere { center, radius } => {
1169                    params.mode = 0;
1170                    params.clip_type = 3;
1171                    params.sphere_cx = center[0];
1172                    params.sphere_cy = center[1];
1173                    params.sphere_cz = center[2];
1174                    params.sphere_radius = radius;
1175                }
1176                crate::renderer::ComputeFilterKind::Threshold { min, max } => {
1177                    params.mode = 1;
1178                    params.threshold_min = min;
1179                    params.threshold_max = max;
1180                }
1181            }
1182
1183            let params_buf = device.create_buffer(&wgpu::BufferDescriptor {
1184                label: Some("compute_filter_params"),
1185                size: std::mem::size_of::<FilterParams>() as u64,
1186                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
1187                mapped_at_creation: false,
1188            });
1189            queue.write_buffer(&params_buf, 0, bytemuck::bytes_of(&params));
1190
1191            // Output index buffer (worst-case: all triangles pass).
1192            let out_index_size = (gpu_mesh.index_count as u64) * 4;
1193            let out_index_buf = device.create_buffer(&wgpu::BufferDescriptor {
1194                label: Some("compute_filter_out_indices"),
1195                size: out_index_size.max(4),
1196                usage: wgpu::BufferUsages::STORAGE
1197                    | wgpu::BufferUsages::INDEX
1198                    | wgpu::BufferUsages::COPY_SRC,
1199                mapped_at_creation: false,
1200            });
1201
1202            // 4-byte atomic counter buffer (cleared to 0).
1203            let counter_buf = device.create_buffer(&wgpu::BufferDescriptor {
1204                label: Some("compute_filter_counter"),
1205                size: 4,
1206                usage: wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_SRC,
1207                mapped_at_creation: true,
1208            });
1209            {
1210                let mut view = counter_buf.slice(..).get_mapped_range_mut();
1211                view[0..4].copy_from_slice(&0u32.to_le_bytes());
1212            }
1213            counter_buf.unmap();
1214
1215            // Staging buffer to read back the counter.
1216            let staging_buf = device.create_buffer(&wgpu::BufferDescriptor {
1217                label: Some("compute_filter_counter_staging"),
1218                size: 4,
1219                usage: wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::COPY_DST,
1220                mapped_at_creation: false,
1221            });
1222
1223            // Pick the scalar buffer: named attribute or dummy.
1224            let scalar_buf_ref: &wgpu::Buffer = match &item.kind {
1225                crate::renderer::ComputeFilterKind::Threshold { .. } => {
1226                    if let Some(attr_name) = &item.attribute_name {
1227                        gpu_mesh
1228                            .attribute_buffers
1229                            .get(attr_name.as_str())
1230                            .unwrap_or(&dummy_scalar_buf)
1231                    } else {
1232                        &dummy_scalar_buf
1233                    }
1234                }
1235                // Clip variants don't use the scalar buffer.
1236                _ => &dummy_scalar_buf,
1237            };
1238
1239            // Build bind group.
1240            let bgl = self.compute_filter_bgl.as_ref().unwrap();
1241            let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
1242                label: Some("compute_filter_bg"),
1243                layout: bgl,
1244                entries: &[
1245                    wgpu::BindGroupEntry {
1246                        binding: 0,
1247                        resource: params_buf.as_entire_binding(),
1248                    },
1249                    wgpu::BindGroupEntry {
1250                        binding: 1,
1251                        resource: gpu_mesh.vertex_buffer.as_entire_binding(),
1252                    },
1253                    wgpu::BindGroupEntry {
1254                        binding: 2,
1255                        resource: gpu_mesh.index_buffer.as_entire_binding(),
1256                    },
1257                    wgpu::BindGroupEntry {
1258                        binding: 3,
1259                        resource: scalar_buf_ref.as_entire_binding(),
1260                    },
1261                    wgpu::BindGroupEntry {
1262                        binding: 4,
1263                        resource: out_index_buf.as_entire_binding(),
1264                    },
1265                    wgpu::BindGroupEntry {
1266                        binding: 5,
1267                        resource: counter_buf.as_entire_binding(),
1268                    },
1269                ],
1270            });
1271
1272            // Encode and submit compute + counter copy.
1273            let mut encoder = device.create_command_encoder(&wgpu::CommandEncoderDescriptor {
1274                label: Some("compute_filter_encoder"),
1275            });
1276
1277            {
1278                let pipeline = self.compute_filter_pipeline.as_ref().unwrap();
1279                let mut cpass = encoder.begin_compute_pass(&wgpu::ComputePassDescriptor {
1280                    label: Some("compute_filter_pass"),
1281                    timestamp_writes: None,
1282                });
1283                cpass.set_pipeline(pipeline);
1284                cpass.set_bind_group(0, &bind_group, &[]);
1285                let workgroups = triangle_count.div_ceil(64);
1286                cpass.dispatch_workgroups(workgroups, 1, 1);
1287            }
1288
1289            encoder.copy_buffer_to_buffer(&counter_buf, 0, &staging_buf, 0, 4);
1290            queue.submit(std::iter::once(encoder.finish()));
1291
1292            // Synchronous readback (v1 : acceptable; async readback can follow later).
1293            let slice = staging_buf.slice(..);
1294            slice.map_async(wgpu::MapMode::Read, |_| {});
1295            let _ = device.poll(wgpu::PollType::Wait {
1296                submission_index: None,
1297                timeout: Some(std::time::Duration::from_secs(5)),
1298            });
1299
1300            let index_count = {
1301                let data = slice.get_mapped_range();
1302                u32::from_le_bytes([data[0], data[1], data[2], data[3]])
1303            };
1304            staging_buf.unmap();
1305
1306            results.push(ComputeFilterResult {
1307                index_buffer: out_index_buf,
1308                index_count,
1309                mesh_id: item.mesh_id,
1310            });
1311        }
1312
1313        results
1314    }
1315
1316    // -----------------------------------------------------------------------
1317    // Phase K: GPU object-ID picking pipeline (lazily created)
1318    // -----------------------------------------------------------------------
1319
1320    /// Lazily create the GPU pick pipeline and associated bind group layouts.
1321    ///
1322    /// No-op if already created. Called from `ViewportRenderer::pick_scene_gpu`
1323    /// on first invocation : zero overhead when GPU picking is never used.
1324    pub(crate) fn ensure_pick_pipeline(&mut self, device: &wgpu::Device) {
1325        if self.pick_pipeline.is_some() {
1326            return;
1327        }
1328
1329        // --- group 0: pick camera bind group layout ---
1330        // Includes binding 0 (CameraUniform) and binding 6 (ClipVolumesUniform).
1331        // The full camera_bind_group_layout has many more bindings; a separate
1332        // minimal layout is cleaner and avoids binding unused resources.
1333        let pick_camera_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
1334            label: Some("pick_camera_bgl"),
1335            entries: &[
1336                wgpu::BindGroupLayoutEntry {
1337                    binding: 0,
1338                    visibility: wgpu::ShaderStages::VERTEX,
1339                    ty: wgpu::BindingType::Buffer {
1340                        ty: wgpu::BufferBindingType::Uniform,
1341                        has_dynamic_offset: false,
1342                        min_binding_size: None,
1343                    },
1344                    count: None,
1345                },
1346                wgpu::BindGroupLayoutEntry {
1347                    binding: 6,
1348                    visibility: wgpu::ShaderStages::FRAGMENT,
1349                    ty: wgpu::BindingType::Buffer {
1350                        ty: wgpu::BufferBindingType::Uniform,
1351                        has_dynamic_offset: false,
1352                        min_binding_size: None,
1353                    },
1354                    count: None,
1355                },
1356            ],
1357        });
1358
1359        // --- group 1: PickInstance storage buffer ---
1360        let pick_instance_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
1361            label: Some("pick_instance_bgl"),
1362            entries: &[wgpu::BindGroupLayoutEntry {
1363                binding: 0,
1364                visibility: wgpu::ShaderStages::VERTEX,
1365                ty: wgpu::BindingType::Buffer {
1366                    ty: wgpu::BufferBindingType::Storage { read_only: true },
1367                    has_dynamic_offset: false,
1368                    min_binding_size: None,
1369                },
1370                count: None,
1371            }],
1372        });
1373
1374        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
1375            label: Some("pick_id_shader"),
1376            source: wgpu::ShaderSource::Wgsl(include_str!("../shaders/pick_id.wgsl").into()),
1377        });
1378
1379        let layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
1380            label: Some("pick_pipeline_layout"),
1381            bind_group_layouts: &[&pick_camera_bgl, &pick_instance_bgl],
1382            push_constant_ranges: &[],
1383        });
1384
1385        // Vertex layout: reuse the 64-byte Vertex stride but only declare position (location 0).
1386        let pick_vertex_layout = wgpu::VertexBufferLayout {
1387            array_stride: std::mem::size_of::<Vertex>() as wgpu::BufferAddress, // 64 bytes
1388            step_mode: wgpu::VertexStepMode::Vertex,
1389            attributes: &[wgpu::VertexAttribute {
1390                offset: 0,
1391                shader_location: 0,
1392                format: wgpu::VertexFormat::Float32x3,
1393            }],
1394        };
1395
1396        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
1397            label: Some("pick_pipeline"),
1398            layout: Some(&layout),
1399            vertex: wgpu::VertexState {
1400                module: &shader,
1401                entry_point: Some("vs_main"),
1402                buffers: &[pick_vertex_layout],
1403                compilation_options: wgpu::PipelineCompilationOptions::default(),
1404            },
1405            fragment: Some(wgpu::FragmentState {
1406                module: &shader,
1407                entry_point: Some("fs_main"),
1408                targets: &[
1409                    // location 0: R32Uint object ID
1410                    Some(wgpu::ColorTargetState {
1411                        format: wgpu::TextureFormat::R32Uint,
1412                        blend: None, // replace : no blending for integer targets
1413                        write_mask: wgpu::ColorWrites::ALL,
1414                    }),
1415                    // location 1: R32Float depth
1416                    Some(wgpu::ColorTargetState {
1417                        format: wgpu::TextureFormat::R32Float,
1418                        blend: None,
1419                        write_mask: wgpu::ColorWrites::ALL,
1420                    }),
1421                ],
1422                compilation_options: wgpu::PipelineCompilationOptions::default(),
1423            }),
1424            primitive: wgpu::PrimitiveState {
1425                topology: wgpu::PrimitiveTopology::TriangleList,
1426                front_face: wgpu::FrontFace::Ccw,
1427                cull_mode: None, // No culling: 3D meshes are often rendered two-sided; pick both faces.
1428                ..Default::default()
1429            },
1430            depth_stencil: Some(wgpu::DepthStencilState {
1431                format: wgpu::TextureFormat::Depth24PlusStencil8,
1432                depth_write_enabled: true,
1433                depth_compare: wgpu::CompareFunction::Less,
1434                stencil: wgpu::StencilState::default(),
1435                bias: wgpu::DepthBiasState::default(),
1436            }),
1437            multisample: wgpu::MultisampleState {
1438                count: 1, // pick pass is always 1x (no MSAA)
1439                ..Default::default()
1440            },
1441            multiview: None,
1442            cache: None,
1443        });
1444
1445        self.pick_camera_bgl = Some(pick_camera_bgl);
1446        self.pick_bind_group_layout_1 = Some(pick_instance_bgl);
1447        self.pick_pipeline = Some(pipeline);
1448    }
1449}
1450
1451// ---------------------------------------------------------------------------
1452// Attribute interpolation utilities
1453// ---------------------------------------------------------------------------
1454
1455/// Linearly interpolate between two attribute buffers element-wise.
1456///
1457/// Both slices must have the same length. `t` is clamped to `[0.0, 1.0]`.
1458/// Returns a new `Vec<f32>` with `a[i] * (1 - t) + b[i] * t`.
1459///
1460/// Use this to blend per-vertex scalar attributes between two consecutive
1461/// timesteps when scrubbing the timeline at sub-frame resolution.
1462pub fn lerp_attributes(a: &[f32], b: &[f32], t: f32) -> Vec<f32> {
1463    let t = t.clamp(0.0, 1.0);
1464    let one_minus_t = 1.0 - t;
1465    a.iter()
1466        .zip(b.iter())
1467        .map(|(&av, &bv)| av * one_minus_t + bv * t)
1468        .collect()
1469}
viewport_lib/resources/extra_impls.rs

viewport_lib/resources/
extra_impls.rs
