roast2d_internal 0.4.0

//! Standard Blinn-Phong mesh shader.

use std::borrow::Cow;

use glam::Mat4;

use crate::color::Color;
use crate::engine::Engine;
use crate::light3d::Material3D;
use crate::platform::types::TextureResource;

use super::geometry::DrawMode;
use super::mesh::Mesh3D;
use super::skinned::SkinnedMesh3D;
use super::vertex::Mesh3DVertex;

/// Resolved draw command with texture bind group
pub struct ResolvedDraw3DSkinned {
    pub mesh: SkinnedMesh3D,
    pub model: Mat4,
    pub color: Color,
    pub material: Material3D,
    pub bone_matrices: Vec<Mat4>,
    pub texture_bind_group: Option<wgpu::BindGroup>,
}

/// Uniform data for 3D mesh rendering
#[repr(C)]
#[derive(Clone, Copy, bytemuck::Pod, bytemuck::Zeroable, Debug)]
struct Mesh3DUniform {
    // Matrices (16 floats each)
    mvp: [[f32; 4]; 4],
    model: [[f32; 4]; 4],
    // Camera
    camera_pos: [f32; 4], // w unused
    // Material
    diffuse: [f32; 4],
    specular: [f32; 4],
    emissive: [f32; 4],
    // Lighting
    ambient: [f32; 4],
    light_dir: [f32; 4], // direction for directional/spot lights
    light_color: [f32; 4],
    light_pos: [f32; 4], // position for point/spot, w = light type (0=dir, 1=point, 2=spot)
    light_params: [f32; 4], // x=radius, y=inner_angle, z=outer_angle, w=intensity
    // Misc
    shininess: f32,
    has_texture: f32,
    _padding: [f32; 2],
}

/// Maximum number of 3D draw calls per frame
const MAX_MESH3D_DRAWS: usize = 256;

pub struct Mesh3DShader {
    pipeline_solid: wgpu::RenderPipeline,
    pipeline_wireframe: wgpu::RenderPipeline,
    pipeline_points: wgpu::RenderPipeline,
    uniform: wgpu::Buffer,
    /// Alignment for dynamic uniform buffer offsets
    uniform_alignment: u32,
    #[allow(dead_code)]
    uniform_bind_group_layout: wgpu::BindGroupLayout,
    uniform_bind_group: wgpu::BindGroup,
    texture_bind_group_layout: wgpu::BindGroupLayout,
    /// Default white 1x1 texture used when no texture is specified
    #[allow(dead_code)]
    default_texture: TextureResource,
    default_texture_bind_group: wgpu::BindGroup,
    /// Cache for texture bind groups, keyed by texture pointer
    texture_bind_group_cache: hashbrown::HashMap<usize, wgpu::BindGroup>,
}

impl Mesh3DShader {
    /// Create a basic 3D mesh renderer targeting the surface format
    /// (works for offscreen textures created with the same format).
    pub fn new(g: &Engine) -> Self {
        let state = g.backend_state();
        let device = &state.device;
        let format = state.surface_view_format;

        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("mesh3d.shader"),
            source: wgpu::ShaderSource::Wgsl(Cow::Borrowed(include_str!(
                "../../assets/shaders/mesh3d.wgsl"
            ))),
        });

        // Get the minimum uniform buffer offset alignment
        let uniform_alignment = device.limits().min_uniform_buffer_offset_alignment;
        // Calculate aligned size for each uniform block
        let uniform_size = std::mem::size_of::<Mesh3DUniform>() as u32;
        let aligned_uniform_size = uniform_size.div_ceil(uniform_alignment) * uniform_alignment;

        // Create a large uniform buffer for dynamic offsets (supports up to MAX_MESH3D_DRAWS draw calls)
        let uniform = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("mesh3d.uniform"),
            size: (aligned_uniform_size as usize * MAX_MESH3D_DRAWS) as u64,
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        let uniform_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: Some("mesh3d.uniform_bgl"),
                entries: &[wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::VERTEX | wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: true,
                        min_binding_size: wgpu::BufferSize::new(uniform_size as u64),
                    },
                    count: None,
                }],
            });

        let uniform_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("mesh3d.uniform_bg"),
            layout: &uniform_bind_group_layout,
            entries: &[wgpu::BindGroupEntry {
                binding: 0,
                resource: wgpu::BindingResource::Buffer(wgpu::BufferBinding {
                    buffer: &uniform,
                    offset: 0,
                    size: wgpu::BufferSize::new(uniform_size as u64),
                }),
            }],
        });

        // Texture bind group layout
        let texture_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: Some("mesh3d.texture_bgl"),
                entries: &[
                    wgpu::BindGroupLayoutEntry {
                        binding: 0,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            sample_type: wgpu::TextureSampleType::Float { filterable: true },
                            view_dimension: wgpu::TextureViewDimension::D2,
                            multisampled: false,
                        },
                        count: None,
                    },
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                        count: None,
                    },
                ],
            });

        // Create default white 1x1 texture
        let default_texture = Self::create_default_texture(device, &state.queue);
        let default_texture_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("mesh3d.default_texture_bg"),
            layout: &texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&default_texture.view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&default_texture.sampler),
                },
            ],
        });

        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("mesh3d.pl"),
            bind_group_layouts: &[&uniform_bind_group_layout, &texture_bind_group_layout],
            push_constant_ranges: &[],
        });

        // Helper closure to create a pipeline with given settings
        let create_pipeline = |label: &str,
                               topology: wgpu::PrimitiveTopology,
                               polygon_mode: wgpu::PolygonMode,
                               cull_mode: Option<wgpu::Face>|
         -> wgpu::RenderPipeline {
            device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
                    label: Some(label),
                    layout: Some(&pipeline_layout),
                    cache: None,
                    vertex: wgpu::VertexState {
                        module: &shader,
                        entry_point: Some("vs_main"),
                        buffers: &[wgpu::VertexBufferLayout {
                            array_stride: std::mem::size_of::<Mesh3DVertex>() as wgpu::BufferAddress,
                            step_mode: wgpu::VertexStepMode::Vertex,
                            attributes: &wgpu::vertex_attr_array![0 => Float32x3, 1 => Float32x3, 2 => Float32x2],
                        }],
                        compilation_options: Default::default(),
                    },
                    fragment: Some(wgpu::FragmentState {
                        module: &shader,
                        entry_point: Some("fs_main"),
                        targets: &[Some(wgpu::ColorTargetState {
                            format,
                            blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                            write_mask: wgpu::ColorWrites::ALL,
                        })],
                        compilation_options: Default::default(),
                    }),
                    primitive: wgpu::PrimitiveState {
                        topology,
                        cull_mode,
                        front_face: wgpu::FrontFace::Ccw,
                        polygon_mode,
                        ..Default::default()
                    },
                    depth_stencil: Some(wgpu::DepthStencilState {
                        format: wgpu::TextureFormat::Depth32Float,
                        depth_write_enabled: true,
                        depth_compare: wgpu::CompareFunction::Greater,
                        stencil: wgpu::StencilState::default(),
                        bias: wgpu::DepthBiasState::default(),
                    }),
                    multisample: wgpu::MultisampleState::default(),
                    multiview: None,
                })
        };

        let pipeline_solid = create_pipeline(
            "mesh3d.pipeline.solid",
            wgpu::PrimitiveTopology::TriangleList,
            wgpu::PolygonMode::Fill,
            Some(wgpu::Face::Back),
        );
        // Note: True wireframe mode requires the POLYGON_MODE_LINE feature which
        // is not available on all platforms. We fall back to solid rendering.
        // TODO: Generate line indices from triangle indices for proper wireframe support
        let pipeline_wireframe = create_pipeline(
            "mesh3d.pipeline.wireframe",
            wgpu::PrimitiveTopology::TriangleList,
            wgpu::PolygonMode::Fill,
            None, // No culling for wireframe
        );
        // Points mode uses PointList topology - renders vertices as points
        let pipeline_points = create_pipeline(
            "mesh3d.pipeline.points",
            wgpu::PrimitiveTopology::PointList,
            wgpu::PolygonMode::Fill,
            None, // No culling for points
        );

        Self {
            pipeline_solid,
            pipeline_wireframe,
            pipeline_points,
            uniform,
            uniform_alignment,
            uniform_bind_group_layout,
            uniform_bind_group,
            texture_bind_group_layout,
            default_texture,
            default_texture_bind_group,
            texture_bind_group_cache: hashbrown::HashMap::new(),
        }
    }

    /// Create a default white 1x1 texture
    pub(super) fn create_default_texture(
        device: &wgpu::Device,
        queue: &wgpu::Queue,
    ) -> TextureResource {
        let size = wgpu::Extent3d {
            width: 1,
            height: 1,
            depth_or_array_layers: 1,
        };
        let texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("mesh3d.default_texture"),
            size,
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba8UnormSrgb,
            usage: wgpu::TextureUsages::COPY_DST | wgpu::TextureUsages::TEXTURE_BINDING,
            view_formats: &[],
        });
        // White pixel
        queue.write_texture(
            wgpu::TexelCopyTextureInfo {
                texture: &texture,
                mip_level: 0,
                origin: wgpu::Origin3d::ZERO,
                aspect: wgpu::TextureAspect::All,
            },
            &[255u8, 255, 255, 255],
            wgpu::TexelCopyBufferLayout {
                offset: 0,
                bytes_per_row: Some(4),
                rows_per_image: Some(1),
            },
            size,
        );
        let view = texture.create_view(&wgpu::TextureViewDescriptor::default());
        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            mag_filter: wgpu::FilterMode::Linear,
            min_filter: wgpu::FilterMode::Linear,
            ..Default::default()
        });
        TextureResource {
            texture,
            view,
            sampler,
        }
    }

    /// Clear texture bind group cache at frame start
    pub fn frame_start(&mut self) {
        self.texture_bind_group_cache.clear();
    }

    /// Create a texture bind group for a given texture resource
    fn create_texture_bind_group(
        &self,
        device: &wgpu::Device,
        texture: &TextureResource,
    ) -> wgpu::BindGroup {
        device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: Some("mesh3d.texture_bg"),
            layout: &self.texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&texture.view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&texture.sampler),
                },
            ],
        })
    }

    /// Get or create a cached texture bind group
    fn get_or_create_texture_bind_group(
        &mut self,
        device: &wgpu::Device,
        texture: &TextureResource,
    ) {
        let key = std::ptr::from_ref(&texture.texture) as usize;
        if !self.texture_bind_group_cache.contains_key(&key) {
            let bg = self.create_texture_bind_group(device, texture);
            self.texture_bind_group_cache.insert(key, bg);
        }
    }

    /// Record drawing of meshes into the provided encoder.
    /// Each mesh is drawn with its own model matrix, optional texture, color, material, and draw mode.
    /// If `should_clear` is true, clears color and depth at start of pass.
    #[allow(clippy::type_complexity)]
    #[allow(clippy::too_many_arguments)]
    pub fn record_to_encoder(
        &mut self,
        g: &Engine,
        color_target: &wgpu::Texture,
        depth_view: &wgpu::TextureView,
        view_proj: Mat4,
        draws: &[(
            &Mesh3D,
            Mat4,
            Option<&TextureResource>,
            Color,
            &crate::light3d::Material3D,
            DrawMode,
        )],
        encoder: &mut wgpu::CommandEncoder,
        should_clear: bool,
    ) {
        let color_view = color_target.create_view(&wgpu::TextureViewDescriptor::default());
        let state = g.backend_state();
        let lighting = g.lighting();
        let camera = g.camera3d();

        // Get the first enabled light of any type
        let (light_dir, light_color, light_pos, light_params) = lighting
            .lights
            .iter()
            .flatten()
            .find(|l| l.enabled)
            .map(|l| {
                use crate::light3d::LightKind;
                let (light_type, radius, inner_angle, outer_angle) = match l.kind {
                    LightKind::Directional => (0.0, 0.0, 0.0, 0.0),
                    LightKind::Point { radius } => (1.0, radius, 0.0, 0.0),
                    LightKind::Spot {
                        radius,
                        inner_angle,
                        outer_angle,
                    } => (2.0, radius, inner_angle, outer_angle),
                };
                (
                    l.direction,
                    l.color,
                    [l.position.x, l.position.y, l.position.z, light_type],
                    [radius, inner_angle, outer_angle, l.intensity],
                )
            })
            .unwrap_or_else(|| {
                (
                    glam::Vec3::new(0.5, -1.0, -0.5).normalize(),
                    Color::rgb(1.0, 1.0, 1.0),
                    [0.0, 0.0, 0.0, 0.0], // Directional light by default
                    [0.0, 0.0, 0.0, 1.0], // Intensity = 1.0
                )
            });

        // Calculate aligned uniform size
        let uniform_size = std::mem::size_of::<Mesh3DUniform>() as u32;
        let aligned_uniform_size =
            uniform_size.div_ceil(self.uniform_alignment) * self.uniform_alignment;

        // Pre-compute all uniform data and cache texture bind groups BEFORE the render pass
        let draw_count = draws.len().min(MAX_MESH3D_DRAWS);
        let mut uniform_data_buffer = vec![0u8; aligned_uniform_size as usize * draw_count];

        // First pass: populate bind group cache and build uniform data
        for (i, (_, model, texture_res, color, material, _)) in
            draws.iter().take(draw_count).enumerate()
        {
            let mvp = view_proj * *model;

            // Cache texture bind group and determine has_texture flag
            let has_texture = if let Some(tex_res) = texture_res {
                // Populate cache (this is idempotent for same texture)
                self.get_or_create_texture_bind_group(&state.device, tex_res);
                1.0f32
            } else {
                0.0f32
            };

            // Combine material diffuse with color tint
            let diffuse = Color::rgba(
                material.diffuse.r * color.r,
                material.diffuse.g * color.g,
                material.diffuse.b * color.b,
                material.diffuse.a * color.a,
            );

            // Build uniform data
            let uniform_data = Mesh3DUniform {
                mvp: mvp.to_cols_array_2d(),
                model: model.to_cols_array_2d(),
                camera_pos: [camera.eye.x, camera.eye.y, camera.eye.z, 0.0],
                diffuse: [diffuse.r, diffuse.g, diffuse.b, diffuse.a],
                specular: [
                    material.specular.r,
                    material.specular.g,
                    material.specular.b,
                    material.specular.a,
                ],
                emissive: [
                    material.emissive.r,
                    material.emissive.g,
                    material.emissive.b,
                    material.emissive.a,
                ],
                ambient: [
                    lighting.ambient.r,
                    lighting.ambient.g,
                    lighting.ambient.b,
                    lighting.ambient.a,
                ],
                light_dir: [light_dir.x, light_dir.y, light_dir.z, 0.0],
                light_color: [light_color.r, light_color.g, light_color.b, light_color.a],
                light_pos,
                light_params,
                shininess: material.shininess,
                has_texture,
                _padding: [0.0; 2],
            };

            // Copy uniform data to the buffer at the correct offset
            let offset = i * aligned_uniform_size as usize;
            let uniform_bytes = bytemuck::bytes_of(&uniform_data);
            uniform_data_buffer[offset..offset + uniform_bytes.len()]
                .copy_from_slice(uniform_bytes);
        }

        // Write all uniform data to GPU at once, BEFORE the render pass
        state
            .queue
            .write_buffer(&self.uniform, 0, &uniform_data_buffer);

        // Now begin the render pass
        let (color_load, depth_load) = if should_clear {
            (
                wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
                wgpu::LoadOp::Clear(0.0),
            )
        } else {
            (wgpu::LoadOp::Load, wgpu::LoadOp::Load)
        };
        {
            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                label: Some("mesh3d.pass"),
                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                    view: &color_view,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: color_load,
                        store: wgpu::StoreOp::Store,
                    },
                    depth_slice: None,
                })],
                depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                    view: depth_view,
                    depth_ops: Some(wgpu::Operations {
                        load: depth_load,
                        store: wgpu::StoreOp::Store,
                    }),
                    stencil_ops: None,
                }),
                occlusion_query_set: None,
                timestamp_writes: None,
            });

            // Track current pipeline to avoid redundant switches
            let mut current_mode: Option<DrawMode> = None;

            for (i, (mesh, _, texture_res, _, _, draw_mode)) in
                draws.iter().take(draw_count).enumerate()
            {
                // Set pipeline if mode changed
                if current_mode != Some(*draw_mode) {
                    current_mode = Some(*draw_mode);
                    let pipeline = match draw_mode {
                        DrawMode::Solid => &self.pipeline_solid,
                        DrawMode::Wireframe => &self.pipeline_wireframe,
                        DrawMode::Points => &self.pipeline_points,
                    };
                    pass.set_pipeline(pipeline);
                }

                // Set uniform bind group with dynamic offset for this draw call
                let dynamic_offset = (i as u32) * aligned_uniform_size;
                pass.set_bind_group(0, &self.uniform_bind_group, &[dynamic_offset]);

                // Set texture bind group from cache
                if let Some(tex_res) = texture_res {
                    let key = std::ptr::from_ref(&tex_res.texture) as usize;
                    if let Some(bg) = self.texture_bind_group_cache.get(&key) {
                        pass.set_bind_group(1, bg, &[]);
                    } else {
                        pass.set_bind_group(1, &self.default_texture_bind_group, &[]);
                    }
                } else {
                    pass.set_bind_group(1, &self.default_texture_bind_group, &[]);
                }

                pass.set_vertex_buffer(0, mesh.vertex.slice(..));
                pass.set_index_buffer(mesh.index.slice(..), wgpu::IndexFormat::Uint16);
                pass.draw_indexed(0..mesh.index_count, 0, 0..1);
            }
        }
    }
}