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src/scene/hatch_model.rs

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+// HatchModel — CPU-side hatch fill data; rendered entirely on the GPU.
+//
+// The boundary is a closed polygon in world XY coordinates (max 64 vertices).
+// The GPU fragment shader performs point-in-polygon and hatch-line tests so
+// no line geometry is ever tessellated on the CPU.
+
+/// One line family from a PAT-format hatch pattern.
+///
+/// Format mirrors the standard PAT line format:
+///   `angle_deg, x0, y0, dx, dy [, dash1, dash2, ...]`
+///
+/// The perpendicular spacing between adjacent parallel lines is:
+///   `| -dx * sin(angle) + dy * cos(angle) |`
+#[derive(Clone, Debug)]
+pub struct PatFamily {
+    /// Line direction in degrees.
+    pub angle_deg: f32,
+    /// Origin of the first line in this family.
+    pub x0: f32,
+    pub y0: f32,
+    /// Step vector to the next parallel line.
+    pub dx: f32,
+    pub dy: f32,
+    /// Dash/gap sequence: positive = dash length, negative = gap length.
+    /// Empty = solid (no dash pattern).
+    pub dashes: Vec<f32>,
+}
+
+/// Hatch fill pattern.
+#[derive(Clone, Debug)]
+pub enum HatchPattern {
+    /// Opaque solid fill.
+    Solid,
+    /// One or more line families (PAT format).
+    Pattern(Vec<PatFamily>),
+    /// Linear gradient from `color` to `color2` along `angle_deg`.
+    Gradient { angle_deg: f32, color2: [f32; 4] },
+}
+
+/// A hatched region defined by a closed polygon boundary.
+#[derive(Clone, Debug)]
+pub struct HatchModel {
+    /// World XY coordinates of the boundary polygon vertices (max 64).
+    pub boundary: Vec<[f32; 2]>,
+    /// Fill pattern.
+    pub pattern: HatchPattern,
+    /// Catalog name for this pattern (e.g. "ANSI31", "SOLID", "LINEAR").
+    /// Stored so `add_hatch()` can write the correct name to the DXF entity.
+    pub name: String,
+    /// RGBA color in [0,1].
+    pub color: [f32; 4],
+    /// Pattern rotation offset in radians (from DXF `pattern_angle`).
+    /// Applied on top of each family's base angle at render time.
+    pub angle_offset: f32,
+    /// Pattern scale multiplier (from DXF `pattern_scale`).
+    pub scale: f32,
+}