first commit

src/scene/pipeline/hatch_gpu.rs

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+// Hatch GPU buffers — renders hatch fills as shader-driven bounding-box quads.
+//
+// Group 1 bindings per hatch:
+//   binding 0 — HatchUniformData  (64 bytes)   mode, color, angle_offset, scale, gradient params
+//   binding 1 — BoundaryData      (1024 bytes)  up to 64 boundary polygon vertices
+//   binding 2 — FamilyBatchData   (1296 bytes)  up to 16 line families + 128 dash values
+
+use crate::scene::hatch_model::{HatchModel, HatchPattern, PatFamily};
+use iced::wgpu;
+use iced::wgpu::util::DeviceExt;
+
+// ── Constants ──────────────────────────────────────────────────────────────
+
+pub const MAX_FAMILIES: usize = 16;
+pub const MAX_DASHES: usize = 128;
+
+// ── Vertex ────────────────────────────────────────────────────────────────
+
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct HatchVertex {
+    pub pos: [f32; 3],
+    pub _pad: f32,
+}
+
+impl HatchVertex {
+    pub fn layout<'a>() -> wgpu::VertexBufferLayout<'a> {
+        wgpu::VertexBufferLayout {
+            array_stride: std::mem::size_of::<HatchVertex>() as u64,
+            step_mode: wgpu::VertexStepMode::Vertex,
+            attributes: &[wgpu::VertexAttribute {
+                offset: 0,
+                shader_location: 0,
+                format: wgpu::VertexFormat::Float32x3,
+            }],
+        }
+    }
+}
+
+// ── Uniform structs ───────────────────────────────────────────────────────
+
+/// Per-hatch parameters (binding 0).  Must be 64 bytes.
+///
+/// `mode` encoding:
+///   0 → Pattern  (families in FamilyBatchData)
+///   1 → Solid
+///   2 → Gradient (grad_cos/sin/min/range used)
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct HatchUniformData {
+    pub color: [f32; 4],   //  0: primary RGBA / gradient start
+    pub color2: [f32; 4],  // 16: gradient end color
+    pub mode: u32,         // 32: 0=pattern, 1=solid, 2=gradient
+    pub vertex_count: u32, // 36: boundary vertex count
+    pub angle_offset: f32, // 40: pattern rotation (radians)
+    pub scale: f32,        // 44: pattern scale multiplier
+    pub grad_cos: f32,     // 48: gradient direction cos
+    pub grad_sin: f32,     // 52: gradient direction sin
+    pub grad_min: f32,     // 56: gradient proj_min
+    pub grad_range: f32,   // 60: gradient proj_range
+} // total 64 bytes
+
+/// Boundary polygon (binding 1).  Matches WGSL `Boundary`.
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct BoundaryData {
+    pub verts: [[f32; 4]; 64], // world XY in .xy, .zw unused
+}
+
+/// One line family packed for the shader (48 bytes).
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct LineFamilyGpu {
+    pub cos_a: f32,      // cos(angle_rad)
+    pub sin_a: f32,      // sin(angle_rad)
+    pub x0: f32,         // family origin x
+    pub y0: f32,         // family origin y
+    pub dx: f32,         // step vector x
+    pub dy: f32,         // step vector y
+    pub perp_step: f32,  // -dx*sin_a + dy*cos_a  (perpendicular spacing)
+    pub along_step: f32, //  dx*cos_a + dy*sin_a  (along-line phase shift per step)
+    pub line_width: f32, // |perp_step| * 0.08
+    pub period: f32,     // sum of |dash values|  (0 = solid)
+    pub n_dashes: u32,   // number of dash entries (0 = solid)
+    pub dash_off: u32,   // index into FamilyBatchData::dash_values
+}
+
+/// All line families + dash values for one hatch (binding 2).
+/// Total size: 16×48 + 32×16 + 4×4 = 768 + 512 + 16 = 1296 bytes.
+/// dash_values is [f32; 4]×32 so each element is vec4<f32> (16-byte stride, valid in uniform).
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct FamilyBatchData {
+    pub families: [LineFamilyGpu; MAX_FAMILIES], // 768 bytes
+    pub dash_values: [[f32; 4]; 32],             // 512 bytes (128 f32s as 32×vec4)
+    pub n_families: u32,                         //   4 bytes
+    pub _pad: [u32; 3],                          //  12 bytes
+} // 1296 bytes total
+
+// ── Per-hatch GPU handle ───────────────────────────────────────────────────
+
+pub struct HatchGpu {
+    pub vertex_buffer: wgpu::Buffer,
+    pub bind_group: wgpu::BindGroup,
+    _uniform_buf: wgpu::Buffer,
+    _boundary_buf: wgpu::Buffer,
+    _family_buf: wgpu::Buffer,
+}
+
+impl HatchGpu {
+    pub fn new(device: &wgpu::Device, model: &HatchModel, bgl1: &wgpu::BindGroupLayout) -> Self {
+        // ── Decode pattern mode ──────────────────────────────────────────
+        let (mode, color2, grad_cos, grad_sin) = match &model.pattern {
+            HatchPattern::Solid => (1u32, [0.0f32; 4], 0.0f32, 0.0f32),
+            HatchPattern::Pattern(_) => (0u32, [0.0f32; 4], 0.0f32, 0.0f32),
+            HatchPattern::Gradient { angle_deg, color2 } => {
+                let r = angle_deg.to_radians();
+                (2u32, *color2, r.cos(), r.sin())
+            }
+        };
+
+        // ── Bounding box ─────────────────────────────────────────────────
+        let min_x = model
+            .boundary
+            .iter()
+            .map(|v| v[0])
+            .fold(f32::INFINITY, f32::min);
+        let max_x = model
+            .boundary
+            .iter()
+            .map(|v| v[0])
+            .fold(f32::NEG_INFINITY, f32::max);
+        let min_y = model
+            .boundary
+            .iter()
+            .map(|v| v[1])
+            .fold(f32::INFINITY, f32::min);
+        let max_y = model
+            .boundary
+            .iter()
+            .map(|v| v[1])
+            .fold(f32::NEG_INFINITY, f32::max);
+
+        let max_spacing = match &model.pattern {
+            HatchPattern::Pattern(families) => families
+                .iter()
+                .map(|f| perp_spacing(f).abs())
+                .fold(0.0f32, f32::max),
+            _ => 5.0,
+        };
+        let diag = ((max_x - min_x).powi(2) + (max_y - min_y).powi(2)).sqrt();
+        let pad = (diag * 0.8 + max_spacing * 2.0 * model.scale).max(1.0);
+        let (x0, x1, y0, y1) = (min_x - pad, max_x + pad, min_y - pad, max_y + pad);
+
+        let quad = [
+            HatchVertex {
+                pos: [x0, y0, 0.0],
+                _pad: 0.0,
+            },
+            HatchVertex {
+                pos: [x1, y0, 0.0],
+                _pad: 0.0,
+            },
+            HatchVertex {
+                pos: [x1, y1, 0.0],
+                _pad: 0.0,
+            },
+            HatchVertex {
+                pos: [x0, y0, 0.0],
+                _pad: 0.0,
+            },
+            HatchVertex {
+                pos: [x1, y1, 0.0],
+                _pad: 0.0,
+            },
+            HatchVertex {
+                pos: [x0, y1, 0.0],
+                _pad: 0.0,
+            },
+        ];
+        let vertex_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("hatch.vbuf"),
+            contents: bytemuck::cast_slice(&quad),
+            usage: wgpu::BufferUsages::VERTEX,
+        });
+
+        // ── Gradient: projection range ───────────────────────────────────
+        let (grad_min, grad_range) = if mode == 2 {
+            let projs: Vec<f32> = model
+                .boundary
+                .iter()
+                .map(|&[x, y]| x * grad_cos + y * grad_sin)
+                .collect();
+            let proj_min = projs.iter().cloned().fold(f32::INFINITY, f32::min);
+            let proj_max = projs.iter().cloned().fold(f32::NEG_INFINITY, f32::max);
+            (proj_min, (proj_max - proj_min).max(1e-4))
+        } else {
+            (0.0, 1.0)
+        };
+
+        // ── HatchUniformData ─────────────────────────────────────────────
+        let n = model.boundary.len().min(64);
+        let uniform_data = HatchUniformData {
+            color: model.color,
+            color2,
+            mode,
+            vertex_count: n as u32,
+            angle_offset: model.angle_offset,
+            scale: model.scale,
+            grad_cos,
+            grad_sin,
+            grad_min,
+            grad_range,
+        };
+
+        // ── BoundaryData ─────────────────────────────────────────────────
+        let mut boundary_data = BoundaryData {
+            verts: [[0.0; 4]; 64],
+        };
+        for (i, &[x, y]) in model.boundary.iter().take(64).enumerate() {
+            boundary_data.verts[i] = [x, y, 0.0, 0.0];
+        }
+
+        // ── FamilyBatchData ───────────────────────────────────────────────
+        let family_batch = build_family_batch(&model.pattern);
+
+        // ── GPU buffers ───────────────────────────────────────────────────
+        let _uniform_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("hatch.uniforms"),
+            contents: bytemuck::bytes_of(&uniform_data),
+            usage: wgpu::BufferUsages::UNIFORM,
+        });
+        let _boundary_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("hatch.boundary"),
+            contents: bytemuck::bytes_of(&boundary_data),
+            usage: wgpu::BufferUsages::UNIFORM,
+        });
+        let _family_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("hatch.families"),
+            contents: bytemuck::bytes_of(&family_batch),
+            usage: wgpu::BufferUsages::UNIFORM,
+        });
+
+        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            label: Some("hatch.bind_group1"),
+            layout: bgl1,
+            entries: &[
+                wgpu::BindGroupEntry {
+                    binding: 0,
+                    resource: _uniform_buf.as_entire_binding(),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 1,
+                    resource: _boundary_buf.as_entire_binding(),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 2,
+                    resource: _family_buf.as_entire_binding(),
+                },
+            ],
+        });
+
+        Self {
+            vertex_buffer,
+            bind_group,
+            _uniform_buf,
+            _boundary_buf,
+            _family_buf,
+        }
+    }
+}
+
+// ── Helpers ───────────────────────────────────────────────────────────────
+
+/// Perpendicular spacing between adjacent parallel lines.
+/// QCAD PAT format stores (dx, dy) in line-local coordinates: dy = perpendicular, dx = along-line.
+fn perp_spacing(f: &PatFamily) -> f32 {
+    f.dy
+}
+
+/// Pack pattern families into the GPU batch struct.
+fn build_family_batch(pattern: &HatchPattern) -> FamilyBatchData {
+    let mut batch = FamilyBatchData {
+        families: [LineFamilyGpu {
+            cos_a: 0.0,
+            sin_a: 0.0,
+            x0: 0.0,
+            y0: 0.0,
+            dx: 0.0,
+            dy: 0.0,
+            perp_step: 0.0,
+            along_step: 0.0,
+            line_width: 0.0,
+            period: 0.0,
+            n_dashes: 0,
+            dash_off: 0,
+        }; MAX_FAMILIES],
+        dash_values: [[0.0; 4]; 32],
+        n_families: 0,
+        _pad: [0; 3],
+    };
+
+    let HatchPattern::Pattern(families) = pattern else {
+        return batch;
+    };
+
+    let mut dash_cursor: usize = 0;
+
+    for (fi, family) in families.iter().take(MAX_FAMILIES).enumerate() {
+        let angle_r = family.angle_deg.to_radians();
+        let cos_a = angle_r.cos();
+        let sin_a = angle_r.sin();
+        // QCAD PAT local-frame convention: dy = perpendicular spacing, dx = along-line phase shift.
+        let perp_step = family.dy;
+        let along_step = family.dx;
+        let line_width = 0.0_f32; // unused: shader uses screen-space derivative for 1px lines
+
+        // Dash pattern: collect up to available space.
+        let n_avail = MAX_DASHES.saturating_sub(dash_cursor);
+        let n_dashes = family.dashes.len().min(n_avail);
+        let period: f32 = family.dashes[..n_dashes].iter().map(|d| d.abs()).sum();
+
+        let dash_off = dash_cursor as u32;
+        for &d in &family.dashes[..n_dashes] {
+            batch.dash_values[dash_cursor / 4][dash_cursor % 4] = d;
+            dash_cursor += 1;
+        }
+
+        batch.families[fi] = LineFamilyGpu {
+            cos_a,
+            sin_a,
+            x0: family.x0,
+            y0: family.y0,
+            dx: family.dx,
+            dy: family.dy,
+            perp_step,
+            along_step,
+            line_width,
+            period: if n_dashes > 0 { period } else { 0.0 },
+            n_dashes: n_dashes as u32,
+            dash_off,
+        };
+        batch.n_families += 1;
+
+        if dash_cursor >= MAX_DASHES {
+            break;
+        }
+    }
+
+    batch
+}