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                color: 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                color: 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        color: 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            color: 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        color: 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            color: 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        color: 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            color: 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        );
460
461        Ok(())
462    }
463
464    /// Create a camera bind group (group 0) for the given per-viewport buffers.
465    ///
466    /// Per-viewport buffers (camera, clip planes, shadow info, clip volume) are
467    /// passed explicitly. Scene-global resources (lights, shadow atlas, IBL) come
468    /// from shared resources on `self`.
469    ///
470    /// NOTE: The initial bind group in `init.rs` is constructed inline (before
471    /// `Self` exists). Keep the binding layout in sync when modifying either site.
472    pub(crate) fn create_camera_bind_group(
473        &self,
474        device: &wgpu::Device,
475        camera_buf: &wgpu::Buffer,
476        clip_planes_buf: &wgpu::Buffer,
477        shadow_info_buf: &wgpu::Buffer,
478        clip_volume_buf: &wgpu::Buffer,
479        label: &str,
480    ) -> wgpu::BindGroup {
481        let irr = self
482            .ibl_irradiance_view
483            .as_ref()
484            .unwrap_or(&self.ibl_fallback_view);
485        let spec = self
486            .ibl_prefiltered_view
487            .as_ref()
488            .unwrap_or(&self.ibl_fallback_view);
489        let brdf = self
490            .ibl_brdf_lut_view
491            .as_ref()
492            .unwrap_or(&self.ibl_fallback_brdf_view);
493        let skybox = self
494            .ibl_skybox_view
495            .as_ref()
496            .unwrap_or(&self.ibl_fallback_view);
497
498        device.create_bind_group(&wgpu::BindGroupDescriptor {
499            label: Some(label),
500            layout: &self.camera_bind_group_layout,
501            entries: &[
502                wgpu::BindGroupEntry {
503                    binding: 0,
504                    resource: camera_buf.as_entire_binding(),
505                },
506                wgpu::BindGroupEntry {
507                    binding: 1,
508                    resource: wgpu::BindingResource::TextureView(&self.shadow_map_view),
509                },
510                wgpu::BindGroupEntry {
511                    binding: 2,
512                    resource: wgpu::BindingResource::Sampler(&self.shadow_sampler),
513                },
514                wgpu::BindGroupEntry {
515                    binding: 3,
516                    resource: self.light_uniform_buf.as_entire_binding(),
517                },
518                wgpu::BindGroupEntry {
519                    binding: 4,
520                    resource: clip_planes_buf.as_entire_binding(),
521                },
522                wgpu::BindGroupEntry {
523                    binding: 5,
524                    resource: shadow_info_buf.as_entire_binding(),
525                },
526                wgpu::BindGroupEntry {
527                    binding: 6,
528                    resource: clip_volume_buf.as_entire_binding(),
529                },
530                wgpu::BindGroupEntry {
531                    binding: 7,
532                    resource: wgpu::BindingResource::TextureView(irr),
533                },
534                wgpu::BindGroupEntry {
535                    binding: 8,
536                    resource: wgpu::BindingResource::TextureView(spec),
537                },
538                wgpu::BindGroupEntry {
539                    binding: 9,
540                    resource: wgpu::BindingResource::TextureView(brdf),
541                },
542                wgpu::BindGroupEntry {
543                    binding: 10,
544                    resource: wgpu::BindingResource::Sampler(&self.ibl_sampler),
545                },
546                wgpu::BindGroupEntry {
547                    binding: 11,
548                    resource: wgpu::BindingResource::TextureView(skybox),
549                },
550            ],
551        })
552    }
553}
554
555// ---------------------------------------------------------------------------
556// Phase G : GPU compute filter pipeline and dispatch
557// ---------------------------------------------------------------------------
558
559/// Output from a single GPU compute filter dispatch.
560///
561/// Contains a compacted index buffer (triangles that passed the filter)
562/// and the count of valid indices. The renderer swaps this in during draw.
563pub struct ComputeFilterResult {
564    /// Output index buffer containing only passing triangles.
565    pub index_buffer: wgpu::Buffer,
566    /// Number of valid indices in `index_buffer` (may be 0 if all filtered).
567    pub index_count: u32,
568    /// `MeshId` this result corresponds to.
569    pub mesh_id: crate::resources::mesh_store::MeshId,
570}
571
572impl ViewportGpuResources {
573    /// Lazily create the GPU compute filter pipeline on first use.
574    fn ensure_compute_filter_pipeline(&mut self, device: &wgpu::Device) {
575        if self.compute_filter_pipeline.is_some() {
576            return;
577        }
578
579        // Build bind group layout.
580        let bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
581            label: Some("compute_filter_bgl"),
582            entries: &[
583                // binding 0: params uniform
584                wgpu::BindGroupLayoutEntry {
585                    binding: 0,
586                    visibility: wgpu::ShaderStages::COMPUTE,
587                    ty: wgpu::BindingType::Buffer {
588                        ty: wgpu::BufferBindingType::Uniform,
589                        has_dynamic_offset: false,
590                        min_binding_size: None,
591                    },
592                    count: None,
593                },
594                // binding 1: vertices (f32 storage, read)
595                wgpu::BindGroupLayoutEntry {
596                    binding: 1,
597                    visibility: wgpu::ShaderStages::COMPUTE,
598                    ty: wgpu::BindingType::Buffer {
599                        ty: wgpu::BufferBindingType::Storage { read_only: true },
600                        has_dynamic_offset: false,
601                        min_binding_size: None,
602                    },
603                    count: None,
604                },
605                // binding 2: source indices (u32 storage, read)
606                wgpu::BindGroupLayoutEntry {
607                    binding: 2,
608                    visibility: wgpu::ShaderStages::COMPUTE,
609                    ty: wgpu::BindingType::Buffer {
610                        ty: wgpu::BufferBindingType::Storage { read_only: true },
611                        has_dynamic_offset: false,
612                        min_binding_size: None,
613                    },
614                    count: None,
615                },
616                // binding 3: scalars (f32 storage, read) : dummy for Clip
617                wgpu::BindGroupLayoutEntry {
618                    binding: 3,
619                    visibility: wgpu::ShaderStages::COMPUTE,
620                    ty: wgpu::BindingType::Buffer {
621                        ty: wgpu::BufferBindingType::Storage { read_only: true },
622                        has_dynamic_offset: false,
623                        min_binding_size: None,
624                    },
625                    count: None,
626                },
627                // binding 4: output compacted indices (read_write)
628                wgpu::BindGroupLayoutEntry {
629                    binding: 4,
630                    visibility: wgpu::ShaderStages::COMPUTE,
631                    ty: wgpu::BindingType::Buffer {
632                        ty: wgpu::BufferBindingType::Storage { read_only: false },
633                        has_dynamic_offset: false,
634                        min_binding_size: None,
635                    },
636                    count: None,
637                },
638                // binding 5: atomic counter (read_write)
639                wgpu::BindGroupLayoutEntry {
640                    binding: 5,
641                    visibility: wgpu::ShaderStages::COMPUTE,
642                    ty: wgpu::BindingType::Buffer {
643                        ty: wgpu::BufferBindingType::Storage { read_only: false },
644                        has_dynamic_offset: false,
645                        min_binding_size: None,
646                    },
647                    count: None,
648                },
649            ],
650        });
651
652        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
653            label: Some("compute_filter_layout"),
654            bind_group_layouts: &[&bgl],
655            push_constant_ranges: &[],
656        });
657
658        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
659            label: Some("compute_filter_shader"),
660            source: wgpu::ShaderSource::Wgsl(include_str!("../shaders/compute_filter.wgsl").into()),
661        });
662
663        let pipeline = device.create_compute_pipeline(&wgpu::ComputePipelineDescriptor {
664            label: Some("compute_filter_pipeline"),
665            layout: Some(&pipeline_layout),
666            module: &shader,
667            entry_point: Some("main"),
668            compilation_options: Default::default(),
669            cache: None,
670        });
671
672        self.compute_filter_bgl = Some(bgl);
673        self.compute_filter_pipeline = Some(pipeline);
674    }
675
676    // -----------------------------------------------------------------------
677    // Phase J: OIT (order-independent transparency) resource management
678    // -----------------------------------------------------------------------
679
680    /// Ensure OIT accum/reveal textures, pipelines, and composite bind group exist
681    /// for the given viewport size.  Call once per frame before the OIT pass.
682    ///
683    /// Early-returns immediately if the size is unchanged and all resources are present.
684    #[allow(dead_code)]
685    pub(crate) fn ensure_oit_targets(&mut self, device: &wgpu::Device, w: u32, h: u32) {
686        let w = w.max(1);
687        let h = h.max(1);
688
689        // Only recreate textures and the composite bind group when size changes.
690        let need_textures = self.oit_size != [w, h] || self.oit_accum_texture.is_none();
691
692        if need_textures {
693            self.oit_size = [w, h];
694
695            // Accum texture: Rgba16Float for accumulation of weighted color+alpha.
696            let accum_tex = device.create_texture(&wgpu::TextureDescriptor {
697                label: Some("oit_accum_texture"),
698                size: wgpu::Extent3d {
699                    width: w,
700                    height: h,
701                    depth_or_array_layers: 1,
702                },
703                mip_level_count: 1,
704                sample_count: 1,
705                dimension: wgpu::TextureDimension::D2,
706                format: wgpu::TextureFormat::Rgba16Float,
707                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
708                    | wgpu::TextureUsages::TEXTURE_BINDING,
709                view_formats: &[],
710            });
711            let accum_view = accum_tex.create_view(&wgpu::TextureViewDescriptor::default());
712
713            // Reveal texture: R8Unorm for transmittance accumulation.
714            let reveal_tex = device.create_texture(&wgpu::TextureDescriptor {
715                label: Some("oit_reveal_texture"),
716                size: wgpu::Extent3d {
717                    width: w,
718                    height: h,
719                    depth_or_array_layers: 1,
720                },
721                mip_level_count: 1,
722                sample_count: 1,
723                dimension: wgpu::TextureDimension::D2,
724                format: wgpu::TextureFormat::R8Unorm,
725                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
726                    | wgpu::TextureUsages::TEXTURE_BINDING,
727                view_formats: &[],
728            });
729            let reveal_view = reveal_tex.create_view(&wgpu::TextureViewDescriptor::default());
730
731            // Create or reuse the OIT sampler.
732            let sampler = if self.oit_composite_sampler.is_none() {
733                device.create_sampler(&wgpu::SamplerDescriptor {
734                    label: Some("oit_composite_sampler"),
735                    address_mode_u: wgpu::AddressMode::ClampToEdge,
736                    address_mode_v: wgpu::AddressMode::ClampToEdge,
737                    address_mode_w: wgpu::AddressMode::ClampToEdge,
738                    mag_filter: wgpu::FilterMode::Linear,
739                    min_filter: wgpu::FilterMode::Linear,
740                    ..Default::default()
741                })
742            } else {
743                // We can't move out of self here, so create a new one.
744                device.create_sampler(&wgpu::SamplerDescriptor {
745                    label: Some("oit_composite_sampler"),
746                    address_mode_u: wgpu::AddressMode::ClampToEdge,
747                    address_mode_v: wgpu::AddressMode::ClampToEdge,
748                    address_mode_w: wgpu::AddressMode::ClampToEdge,
749                    mag_filter: wgpu::FilterMode::Linear,
750                    min_filter: wgpu::FilterMode::Linear,
751                    ..Default::default()
752                })
753            };
754
755            // Create BGL once.
756            let bgl = if self.oit_composite_bgl.is_none() {
757                let bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
758                    label: Some("oit_composite_bgl"),
759                    entries: &[
760                        wgpu::BindGroupLayoutEntry {
761                            binding: 0,
762                            visibility: wgpu::ShaderStages::FRAGMENT,
763                            ty: wgpu::BindingType::Texture {
764                                sample_type: wgpu::TextureSampleType::Float { filterable: true },
765                                view_dimension: wgpu::TextureViewDimension::D2,
766                                multisampled: false,
767                            },
768                            count: None,
769                        },
770                        wgpu::BindGroupLayoutEntry {
771                            binding: 1,
772                            visibility: wgpu::ShaderStages::FRAGMENT,
773                            ty: wgpu::BindingType::Texture {
774                                sample_type: wgpu::TextureSampleType::Float { filterable: true },
775                                view_dimension: wgpu::TextureViewDimension::D2,
776                                multisampled: false,
777                            },
778                            count: None,
779                        },
780                        wgpu::BindGroupLayoutEntry {
781                            binding: 2,
782                            visibility: wgpu::ShaderStages::FRAGMENT,
783                            ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
784                            count: None,
785                        },
786                    ],
787                });
788                self.oit_composite_bgl = Some(bgl);
789                self.oit_composite_bgl.as_ref().unwrap()
790            } else {
791                self.oit_composite_bgl.as_ref().unwrap()
792            };
793
794            // Composite bind group referencing the new texture views.
795            let composite_bg = device.create_bind_group(&wgpu::BindGroupDescriptor {
796                label: Some("oit_composite_bind_group"),
797                layout: bgl,
798                entries: &[
799                    wgpu::BindGroupEntry {
800                        binding: 0,
801                        resource: wgpu::BindingResource::TextureView(&accum_view),
802                    },
803                    wgpu::BindGroupEntry {
804                        binding: 1,
805                        resource: wgpu::BindingResource::TextureView(&reveal_view),
806                    },
807                    wgpu::BindGroupEntry {
808                        binding: 2,
809                        resource: wgpu::BindingResource::Sampler(&sampler),
810                    },
811                ],
812            });
813
814            self.oit_accum_texture = Some(accum_tex);
815            self.oit_accum_view = Some(accum_view);
816            self.oit_reveal_texture = Some(reveal_tex);
817            self.oit_reveal_view = Some(reveal_view);
818            self.oit_composite_sampler = Some(sampler);
819            self.oit_composite_bind_group = Some(composite_bg);
820        }
821
822        // Create pipelines once (they don't depend on viewport size).
823        if self.oit_pipeline.is_none() {
824            // Non-instanced OIT pipeline (mesh_oit.wgsl, group 0 = camera BGL, group 1 = object BGL).
825            let oit_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
826                label: Some("mesh_oit_shader"),
827                source: wgpu::ShaderSource::Wgsl(include_str!("../shaders/mesh_oit.wgsl").into()),
828            });
829            let oit_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
830                label: Some("oit_pipeline_layout"),
831                bind_group_layouts: &[
832                    &self.camera_bind_group_layout,
833                    &self.object_bind_group_layout,
834                ],
835                push_constant_ranges: &[],
836            });
837
838            // Accum blend: src=One, dst=One, Add (additive accumulation).
839            let accum_blend = wgpu::BlendState {
840                color: wgpu::BlendComponent {
841                    src_factor: wgpu::BlendFactor::One,
842                    dst_factor: wgpu::BlendFactor::One,
843                    operation: wgpu::BlendOperation::Add,
844                },
845                alpha: wgpu::BlendComponent {
846                    src_factor: wgpu::BlendFactor::One,
847                    dst_factor: wgpu::BlendFactor::One,
848                    operation: wgpu::BlendOperation::Add,
849                },
850            };
851
852            // Reveal blend: src=Zero, dst=OneMinusSrcColor (multiplicative transmittance).
853            let reveal_blend = wgpu::BlendState {
854                color: wgpu::BlendComponent {
855                    src_factor: wgpu::BlendFactor::Zero,
856                    dst_factor: wgpu::BlendFactor::OneMinusSrc,
857                    operation: wgpu::BlendOperation::Add,
858                },
859                alpha: wgpu::BlendComponent {
860                    src_factor: wgpu::BlendFactor::Zero,
861                    dst_factor: wgpu::BlendFactor::OneMinusSrc,
862                    operation: wgpu::BlendOperation::Add,
863                },
864            };
865
866            let oit_depth_stencil = wgpu::DepthStencilState {
867                format: wgpu::TextureFormat::Depth24PlusStencil8,
868                depth_write_enabled: false,
869                depth_compare: wgpu::CompareFunction::LessEqual,
870                stencil: wgpu::StencilState::default(),
871                bias: wgpu::DepthBiasState::default(),
872            };
873
874            let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
875                label: Some("oit_pipeline"),
876                layout: Some(&oit_layout),
877                vertex: wgpu::VertexState {
878                    module: &oit_shader,
879                    entry_point: Some("vs_main"),
880                    buffers: &[Vertex::buffer_layout()],
881                    compilation_options: wgpu::PipelineCompilationOptions::default(),
882                },
883                fragment: Some(wgpu::FragmentState {
884                    module: &oit_shader,
885                    entry_point: Some("fs_oit_main"),
886                    targets: &[
887                        Some(wgpu::ColorTargetState {
888                            format: wgpu::TextureFormat::Rgba16Float,
889                            blend: Some(accum_blend),
890                            write_mask: wgpu::ColorWrites::ALL,
891                        }),
892                        Some(wgpu::ColorTargetState {
893                            format: wgpu::TextureFormat::R8Unorm,
894                            blend: Some(reveal_blend),
895                            write_mask: wgpu::ColorWrites::RED,
896                        }),
897                    ],
898                    compilation_options: wgpu::PipelineCompilationOptions::default(),
899                }),
900                primitive: wgpu::PrimitiveState {
901                    topology: wgpu::PrimitiveTopology::TriangleList,
902                    cull_mode: Some(wgpu::Face::Back),
903                    ..Default::default()
904                },
905                depth_stencil: Some(oit_depth_stencil.clone()),
906                multisample: wgpu::MultisampleState {
907                    count: 1,
908                    ..Default::default()
909                },
910                multiview: None,
911                cache: None,
912            });
913            self.oit_pipeline = Some(pipeline);
914
915            // Instanced OIT pipeline (mesh_instanced_oit.wgsl, two OIT targets).
916            if let Some(ref instance_bgl) = self.instance_bind_group_layout {
917                let instanced_oit_shader =
918                    device.create_shader_module(wgpu::ShaderModuleDescriptor {
919                        label: Some("mesh_instanced_oit_shader"),
920                        source: wgpu::ShaderSource::Wgsl(
921                            include_str!("../shaders/mesh_instanced_oit.wgsl").into(),
922                        ),
923                    });
924                let instanced_oit_layout =
925                    device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
926                        label: Some("oit_instanced_pipeline_layout"),
927                        bind_group_layouts: &[&self.camera_bind_group_layout, instance_bgl],
928                        push_constant_ranges: &[],
929                    });
930                let instanced_pipeline =
931                    device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
932                        label: Some("oit_instanced_pipeline"),
933                        layout: Some(&instanced_oit_layout),
934                        vertex: wgpu::VertexState {
935                            module: &instanced_oit_shader,
936                            entry_point: Some("vs_main"),
937                            buffers: &[Vertex::buffer_layout()],
938                            compilation_options: wgpu::PipelineCompilationOptions::default(),
939                        },
940                        fragment: Some(wgpu::FragmentState {
941                            module: &instanced_oit_shader,
942                            entry_point: Some("fs_oit_main"),
943                            targets: &[
944                                Some(wgpu::ColorTargetState {
945                                    format: wgpu::TextureFormat::Rgba16Float,
946                                    blend: Some(accum_blend),
947                                    write_mask: wgpu::ColorWrites::ALL,
948                                }),
949                                Some(wgpu::ColorTargetState {
950                                    format: wgpu::TextureFormat::R8Unorm,
951                                    blend: Some(reveal_blend),
952                                    write_mask: wgpu::ColorWrites::RED,
953                                }),
954                            ],
955                            compilation_options: wgpu::PipelineCompilationOptions::default(),
956                        }),
957                        primitive: wgpu::PrimitiveState {
958                            topology: wgpu::PrimitiveTopology::TriangleList,
959                            cull_mode: Some(wgpu::Face::Back),
960                            ..Default::default()
961                        },
962                        depth_stencil: Some(oit_depth_stencil),
963                        multisample: wgpu::MultisampleState {
964                            count: 1,
965                            ..Default::default()
966                        },
967                        multiview: None,
968                        cache: None,
969                    });
970                self.oit_instanced_pipeline = Some(instanced_pipeline);
971            }
972        }
973
974        if self.oit_composite_pipeline.is_none() {
975            let comp_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
976                label: Some("oit_composite_shader"),
977                source: wgpu::ShaderSource::Wgsl(
978                    include_str!("../shaders/oit_composite.wgsl").into(),
979                ),
980            });
981            let bgl = self
982                .oit_composite_bgl
983                .as_ref()
984                .expect("oit_composite_bgl must exist");
985            let comp_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
986                label: Some("oit_composite_pipeline_layout"),
987                bind_group_layouts: &[bgl],
988                push_constant_ranges: &[],
989            });
990            // Premultiplied alpha blend: One / OneMinusSrcAlpha : composites avg_color*(1-r) onto HDR.
991            let premul_blend = wgpu::BlendState {
992                color: wgpu::BlendComponent {
993                    src_factor: wgpu::BlendFactor::One,
994                    dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
995                    operation: wgpu::BlendOperation::Add,
996                },
997                alpha: wgpu::BlendComponent {
998                    src_factor: wgpu::BlendFactor::One,
999                    dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
1000                    operation: wgpu::BlendOperation::Add,
1001                },
1002            };
1003            let comp_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
1004                label: Some("oit_composite_pipeline"),
1005                layout: Some(&comp_layout),
1006                vertex: wgpu::VertexState {
1007                    module: &comp_shader,
1008                    entry_point: Some("vs_main"),
1009                    buffers: &[],
1010                    compilation_options: wgpu::PipelineCompilationOptions::default(),
1011                },
1012                fragment: Some(wgpu::FragmentState {
1013                    module: &comp_shader,
1014                    entry_point: Some("fs_main"),
1015                    targets: &[Some(wgpu::ColorTargetState {
1016                        format: wgpu::TextureFormat::Rgba16Float,
1017                        blend: Some(premul_blend),
1018                        write_mask: wgpu::ColorWrites::ALL,
1019                    })],
1020                    compilation_options: wgpu::PipelineCompilationOptions::default(),
1021                }),
1022                primitive: wgpu::PrimitiveState {
1023                    topology: wgpu::PrimitiveTopology::TriangleList,
1024                    ..Default::default()
1025                },
1026                depth_stencil: None,
1027                multisample: wgpu::MultisampleState {
1028                    count: 1,
1029                    ..Default::default()
1030                },
1031                multiview: None,
1032                cache: None,
1033            });
1034            self.oit_composite_pipeline = Some(comp_pipeline);
1035        }
1036    }
1037
1038    /// Dispatch GPU compute filters for all items in the list.
1039    ///
1040    /// Returns one [`ComputeFilterResult`] per item. The renderer uses these
1041    /// during `paint()` to override the mesh's default index buffer.
1042    ///
1043    /// This is a synchronous v1 implementation: it submits each dispatch
1044    /// individually and polls the device to read back the counter. This is
1045    /// acceptable for v1; async readback can be added later.
1046    pub fn run_compute_filters(
1047        &mut self,
1048        device: &wgpu::Device,
1049        queue: &wgpu::Queue,
1050        items: &[crate::renderer::ComputeFilterItem],
1051    ) -> Vec<ComputeFilterResult> {
1052        if items.is_empty() {
1053            return Vec::new();
1054        }
1055
1056        self.ensure_compute_filter_pipeline(device);
1057
1058        // Dummy 4-byte buffer used as the scalar binding when doing a Clip filter.
1059        let dummy_scalar_buf = device.create_buffer(&wgpu::BufferDescriptor {
1060            label: Some("compute_filter_dummy_scalar"),
1061            size: 4,
1062            usage: wgpu::BufferUsages::STORAGE,
1063            mapped_at_creation: false,
1064        });
1065
1066        let mut results = Vec::with_capacity(items.len());
1067
1068        for item in items {
1069            // Resolve the mesh.
1070            let gpu_mesh = match self
1071                .mesh_store
1072                .get(item.mesh_id)
1073            {
1074                Some(m) => m,
1075                None => continue,
1076            };
1077
1078            let triangle_count = gpu_mesh.index_count / 3;
1079            if triangle_count == 0 {
1080                continue;
1081            }
1082
1083            // Vertex stride: the Vertex struct is 64 bytes = 16 f32s.
1084            const VERTEX_STRIDE_F32: u32 = 16;
1085
1086            // Build params uniform matching compute_filter.wgsl Params struct layout.
1087            #[repr(C)]
1088            #[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable)]
1089            struct FilterParams {
1090                mode: u32,
1091                clip_type: u32,
1092                threshold_min: f32,
1093                threshold_max: f32,
1094                triangle_count: u32,
1095                vertex_stride_f32: u32,
1096                _pad: [u32; 2],
1097                // Plane params
1098                plane_nx: f32,
1099                plane_ny: f32,
1100                plane_nz: f32,
1101                plane_dist: f32,
1102                // Box params
1103                box_cx: f32,
1104                box_cy: f32,
1105                box_cz: f32,
1106                _padb0: f32,
1107                box_hex: f32,
1108                box_hey: f32,
1109                box_hez: f32,
1110                _padb1: f32,
1111                box_col0x: f32,
1112                box_col0y: f32,
1113                box_col0z: f32,
1114                _padb2: f32,
1115                box_col1x: f32,
1116                box_col1y: f32,
1117                box_col1z: f32,
1118                _padb3: f32,
1119                box_col2x: f32,
1120                box_col2y: f32,
1121                box_col2z: f32,
1122                _padb4: f32,
1123                // Sphere params
1124                sphere_cx: f32,
1125                sphere_cy: f32,
1126                sphere_cz: f32,
1127                sphere_radius: f32,
1128            }
1129
1130            let mut params: FilterParams = bytemuck::Zeroable::zeroed();
1131            params.triangle_count = triangle_count;
1132            params.vertex_stride_f32 = VERTEX_STRIDE_F32;
1133
1134            match item.kind {
1135                crate::renderer::ComputeFilterKind::Clip {
1136                    plane_normal,
1137                    plane_dist,
1138                } => {
1139                    params.mode = 0;
1140                    params.clip_type = 1;
1141                    params.plane_nx = plane_normal[0];
1142                    params.plane_ny = plane_normal[1];
1143                    params.plane_nz = plane_normal[2];
1144                    params.plane_dist = plane_dist;
1145                }
1146                crate::renderer::ComputeFilterKind::ClipBox {
1147                    center,
1148                    half_extents,
1149                    orientation,
1150                } => {
1151                    params.mode = 0;
1152                    params.clip_type = 2;
1153                    params.box_cx = center[0];
1154                    params.box_cy = center[1];
1155                    params.box_cz = center[2];
1156                    params.box_hex = half_extents[0];
1157                    params.box_hey = half_extents[1];
1158                    params.box_hez = half_extents[2];
1159                    params.box_col0x = orientation[0][0];
1160                    params.box_col0y = orientation[0][1];
1161                    params.box_col0z = orientation[0][2];
1162                    params.box_col1x = orientation[1][0];
1163                    params.box_col1y = orientation[1][1];
1164                    params.box_col1z = orientation[1][2];
1165                    params.box_col2x = orientation[2][0];
1166                    params.box_col2y = orientation[2][1];
1167                    params.box_col2z = orientation[2][2];
1168                }
1169                crate::renderer::ComputeFilterKind::ClipSphere { center, radius } => {
1170                    params.mode = 0;
1171                    params.clip_type = 3;
1172                    params.sphere_cx = center[0];
1173                    params.sphere_cy = center[1];
1174                    params.sphere_cz = center[2];
1175                    params.sphere_radius = radius;
1176                }
1177                crate::renderer::ComputeFilterKind::Threshold { min, max } => {
1178                    params.mode = 1;
1179                    params.threshold_min = min;
1180                    params.threshold_max = max;
1181                }
1182            }
1183
1184            let params_buf = device.create_buffer(&wgpu::BufferDescriptor {
1185                label: Some("compute_filter_params"),
1186                size: std::mem::size_of::<FilterParams>() as u64,
1187                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
1188                mapped_at_creation: false,
1189            });
1190            queue.write_buffer(&params_buf, 0, bytemuck::bytes_of(&params));
1191
1192            // Output index buffer (worst-case: all triangles pass).
1193            let out_index_size = (gpu_mesh.index_count as u64) * 4;
1194            let out_index_buf = device.create_buffer(&wgpu::BufferDescriptor {
1195                label: Some("compute_filter_out_indices"),
1196                size: out_index_size.max(4),
1197                usage: wgpu::BufferUsages::STORAGE
1198                    | wgpu::BufferUsages::INDEX
1199                    | wgpu::BufferUsages::COPY_SRC,
1200                mapped_at_creation: false,
1201            });
1202
1203            // 4-byte atomic counter buffer (cleared to 0).
1204            let counter_buf = device.create_buffer(&wgpu::BufferDescriptor {
1205                label: Some("compute_filter_counter"),
1206                size: 4,
1207                usage: wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::COPY_SRC,
1208                mapped_at_creation: true,
1209            });
1210            {
1211                let mut view = counter_buf.slice(..).get_mapped_range_mut();
1212                view[0..4].copy_from_slice(&0u32.to_le_bytes());
1213            }
1214            counter_buf.unmap();
1215
1216            // Staging buffer to read back the counter.
1217            let staging_buf = device.create_buffer(&wgpu::BufferDescriptor {
1218                label: Some("compute_filter_counter_staging"),
1219                size: 4,
1220                usage: wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::COPY_DST,
1221                mapped_at_creation: false,
1222            });
1223
1224            // Pick the scalar buffer: named attribute or dummy.
1225            let scalar_buf_ref: &wgpu::Buffer = match &item.kind {
1226                crate::renderer::ComputeFilterKind::Threshold { .. } => {
1227                    if let Some(attr_name) = &item.attribute_name {
1228                        gpu_mesh
1229                            .attribute_buffers
1230                            .get(attr_name.as_str())
1231                            .unwrap_or(&dummy_scalar_buf)
1232                    } else {
1233                        &dummy_scalar_buf
1234                    }
1235                }
1236                // Clip variants don't use the scalar buffer.
1237                _ => &dummy_scalar_buf,
1238            };
1239
1240            // Build bind group.
1241            let bgl = self.compute_filter_bgl.as_ref().unwrap();
1242            let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
1243                label: Some("compute_filter_bg"),
1244                layout: bgl,
1245                entries: &[
1246                    wgpu::BindGroupEntry {
1247                        binding: 0,
1248                        resource: params_buf.as_entire_binding(),
1249                    },
1250                    wgpu::BindGroupEntry {
1251                        binding: 1,
1252                        resource: gpu_mesh.vertex_buffer.as_entire_binding(),
1253                    },
1254                    wgpu::BindGroupEntry {
1255                        binding: 2,
1256                        resource: gpu_mesh.index_buffer.as_entire_binding(),
1257                    },
1258                    wgpu::BindGroupEntry {
1259                        binding: 3,
1260                        resource: scalar_buf_ref.as_entire_binding(),
1261                    },
1262                    wgpu::BindGroupEntry {
1263                        binding: 4,
1264                        resource: out_index_buf.as_entire_binding(),
1265                    },
1266                    wgpu::BindGroupEntry {
1267                        binding: 5,
1268                        resource: counter_buf.as_entire_binding(),
1269                    },
1270                ],
1271            });
1272
1273            // Encode and submit compute + counter copy.
1274            let mut encoder = device.create_command_encoder(&wgpu::CommandEncoderDescriptor {
1275                label: Some("compute_filter_encoder"),
1276            });
1277
1278            {
1279                let pipeline = self.compute_filter_pipeline.as_ref().unwrap();
1280                let mut cpass = encoder.begin_compute_pass(&wgpu::ComputePassDescriptor {
1281                    label: Some("compute_filter_pass"),
1282                    timestamp_writes: None,
1283                });
1284                cpass.set_pipeline(pipeline);
1285                cpass.set_bind_group(0, &bind_group, &[]);
1286                let workgroups = triangle_count.div_ceil(64);
1287                cpass.dispatch_workgroups(workgroups, 1, 1);
1288            }
1289
1290            encoder.copy_buffer_to_buffer(&counter_buf, 0, &staging_buf, 0, 4);
1291            queue.submit(std::iter::once(encoder.finish()));
1292
1293            // Synchronous readback (v1 : acceptable; async readback can follow later).
1294            let slice = staging_buf.slice(..);
1295            slice.map_async(wgpu::MapMode::Read, |_| {});
1296            let _ = device.poll(wgpu::PollType::Wait {
1297                submission_index: None,
1298                timeout: Some(std::time::Duration::from_secs(5)),
1299            });
1300
1301            let index_count = {
1302                let data = slice.get_mapped_range();
1303                u32::from_le_bytes([data[0], data[1], data[2], data[3]])
1304            };
1305            staging_buf.unmap();
1306
1307            results.push(ComputeFilterResult {
1308                index_buffer: out_index_buf,
1309                index_count,
1310                mesh_id: item.mesh_id,
1311            });
1312        }
1313
1314        results
1315    }
1316
1317    // -----------------------------------------------------------------------
1318    // Phase K: GPU object-ID picking pipeline (lazily created)
1319    // -----------------------------------------------------------------------
1320
1321    /// Lazily create the GPU pick pipeline and associated bind group layouts.
1322    ///
1323    /// No-op if already created. Called from `ViewportRenderer::pick_scene_gpu`
1324    /// on first invocation : zero overhead when GPU picking is never used.
1325    pub(crate) fn ensure_pick_pipeline(&mut self, device: &wgpu::Device) {
1326        if self.pick_pipeline.is_some() {
1327            return;
1328        }
1329
1330        // --- group 0: pick camera bind group layout ---
1331        // Includes binding 0 (CameraUniform) and binding 6 (ClipVolumesUniform).
1332        // The full camera_bind_group_layout has many more bindings; a separate
1333        // minimal layout is cleaner and avoids binding unused resources.
1334        let pick_camera_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
1335            label: Some("pick_camera_bgl"),
1336            entries: &[
1337                wgpu::BindGroupLayoutEntry {
1338                    binding: 0,
1339                    visibility: wgpu::ShaderStages::VERTEX,
1340                    ty: wgpu::BindingType::Buffer {
1341                        ty: wgpu::BufferBindingType::Uniform,
1342                        has_dynamic_offset: false,
1343                        min_binding_size: None,
1344                    },
1345                    count: None,
1346                },
1347                wgpu::BindGroupLayoutEntry {
1348                    binding: 6,
1349                    visibility: wgpu::ShaderStages::FRAGMENT,
1350                    ty: wgpu::BindingType::Buffer {
1351                        ty: wgpu::BufferBindingType::Uniform,
1352                        has_dynamic_offset: false,
1353                        min_binding_size: None,
1354                    },
1355                    count: None,
1356                },
1357            ],
1358        });
1359
1360        // --- group 1: PickInstance storage buffer ---
1361        let pick_instance_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
1362            label: Some("pick_instance_bgl"),
1363            entries: &[wgpu::BindGroupLayoutEntry {
1364                binding: 0,
1365                visibility: wgpu::ShaderStages::VERTEX,
1366                ty: wgpu::BindingType::Buffer {
1367                    ty: wgpu::BufferBindingType::Storage { read_only: true },
1368                    has_dynamic_offset: false,
1369                    min_binding_size: None,
1370                },
1371                count: None,
1372            }],
1373        });
1374
1375        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
1376            label: Some("pick_id_shader"),
1377            source: wgpu::ShaderSource::Wgsl(include_str!("../shaders/pick_id.wgsl").into()),
1378        });
1379
1380        let layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
1381            label: Some("pick_pipeline_layout"),
1382            bind_group_layouts: &[&pick_camera_bgl, &pick_instance_bgl],
1383            push_constant_ranges: &[],
1384        });
1385
1386        // Vertex layout: reuse the 64-byte Vertex stride but only declare position (location 0).
1387        let pick_vertex_layout = wgpu::VertexBufferLayout {
1388            array_stride: std::mem::size_of::<Vertex>() as wgpu::BufferAddress, // 64 bytes
1389            step_mode: wgpu::VertexStepMode::Vertex,
1390            attributes: &[wgpu::VertexAttribute {
1391                offset: 0,
1392                shader_location: 0,
1393                format: wgpu::VertexFormat::Float32x3,
1394            }],
1395        };
1396
1397        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
1398            label: Some("pick_pipeline"),
1399            layout: Some(&layout),
1400            vertex: wgpu::VertexState {
1401                module: &shader,
1402                entry_point: Some("vs_main"),
1403                buffers: &[pick_vertex_layout],
1404                compilation_options: wgpu::PipelineCompilationOptions::default(),
1405            },
1406            fragment: Some(wgpu::FragmentState {
1407                module: &shader,
1408                entry_point: Some("fs_main"),
1409                targets: &[
1410                    // location 0: R32Uint object ID
1411                    Some(wgpu::ColorTargetState {
1412                        format: wgpu::TextureFormat::R32Uint,
1413                        blend: None, // replace : no blending for integer targets
1414                        write_mask: wgpu::ColorWrites::ALL,
1415                    }),
1416                    // location 1: R32Float depth
1417                    Some(wgpu::ColorTargetState {
1418                        format: wgpu::TextureFormat::R32Float,
1419                        blend: None,
1420                        write_mask: wgpu::ColorWrites::ALL,
1421                    }),
1422                ],
1423                compilation_options: wgpu::PipelineCompilationOptions::default(),
1424            }),
1425            primitive: wgpu::PrimitiveState {
1426                topology: wgpu::PrimitiveTopology::TriangleList,
1427                front_face: wgpu::FrontFace::Ccw,
1428                cull_mode: None, // No culling: 3D meshes are often rendered two-sided; pick both faces.
1429                ..Default::default()
1430            },
1431            depth_stencil: Some(wgpu::DepthStencilState {
1432                format: wgpu::TextureFormat::Depth24PlusStencil8,
1433                depth_write_enabled: true,
1434                depth_compare: wgpu::CompareFunction::Less,
1435                stencil: wgpu::StencilState::default(),
1436                bias: wgpu::DepthBiasState::default(),
1437            }),
1438            multisample: wgpu::MultisampleState {
1439                count: 1, // pick pass is always 1x (no MSAA)
1440                ..Default::default()
1441            },
1442            multiview: None,
1443            cache: None,
1444        });
1445
1446        self.pick_camera_bgl = Some(pick_camera_bgl);
1447        self.pick_bind_group_layout_1 = Some(pick_instance_bgl);
1448        self.pick_pipeline = Some(pipeline);
1449    }
1450}
1451
1452// ---------------------------------------------------------------------------
1453// Attribute interpolation utilities
1454// ---------------------------------------------------------------------------
1455
1456/// Linearly interpolate between two attribute buffers element-wise.
1457///
1458/// Both slices must have the same length. `t` is clamped to `[0.0, 1.0]`.
1459/// Returns a new `Vec<f32>` with `a[i] * (1 - t) + b[i] * t`.
1460///
1461/// Use this to blend per-vertex scalar attributes between two consecutive
1462/// timesteps when scrubbing the timeline at sub-frame resolution.
1463pub fn lerp_attributes(a: &[f32], b: &[f32], t: f32) -> Vec<f32> {
1464    let t = t.clamp(0.0, 1.0);
1465    let one_minus_t = 1.0 - t;
1466    a.iter()
1467        .zip(b.iter())
1468        .map(|(&av, &bv)| av * one_minus_t + bv * t)
1469        .collect()
1470}
viewport_lib/resources/extra_impls.rs

viewport_lib/resources/
extra_impls.rs
