forked from 1b-agent/opencadstudio-upstream
Hakan SevenandClaude Opus 4.8
374cf7e89f
Groundwork to render CAD text as per-glyph SDF quads (box-quad snap, perf, no LOD) instead of stroke-polyline wires. CPU side fully tested; GPU side compiles but is not yet wired into the render loop. - scene::text::sdf_atlas — GlyphAtlas: shelf packer + R8 SDF tiles baked per (font, char). Unified field so one shader draws both kinds: TrueType = signed distance to the filled outline, LFF stroke = pen band. Uses only crates already in the tree (ttf-parser/lyon via the existing Glyph). - scene::text::glyph_quads — layout_glyph_quads: lays a run out as per-glyph quads using the exact tessellate_text_run transform, so quads land where the strokes would. Per-char advance (TTF shaping is a follow-up). - shaders/text.wgsl — SDF fragment shader (smoothstep over fwidth), RTE vertex path mirroring image.wgsl, per-vertex colour + draw-order bias. - scene::pipeline::text_gpu — TextVertex + double-single vertex builder, R8 atlas texture upload, bind group, and the image-cloned pipeline. 13 unit tests across the three CPU stages, all green. Modules carry #![allow(dead_code)] until the render-loop integration lands. Co-Authored-By: Claude Opus 4.8 <[email protected]>
72 lines
2.9 KiB
WebGPU Shading Language
72 lines
2.9 KiB
WebGPU Shading Language
// SDF text-quad shader. One quad per glyph, sampling the single-channel SDF
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// glyph atlas (built by scene::text::sdf_atlas). The atlas stores the glyph
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// edge at value 0.5; screen-space derivatives antialias it at any zoom, so no
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// per-size glyph baking or text LOD is needed.
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// ── Bind group 0: shared projection uniforms ─────────────────────────────────
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// Must match the shared `Uniforms` struct (scene::pipeline::uniforms, 112 B).
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struct Uniforms {
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viewport_size: vec2<f32>,
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world_per_pixel: f32,
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lwdisplay_enable: f32,
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flat_shade: f32,
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transparency_enable: f32,
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_pad: vec2<f32>,
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// Relative-to-eye (double-single): see wire.wgsl.
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view_rot: mat4x4<f32>,
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eye_high: vec3<f32>,
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_pad_eh: f32,
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eye_low: vec3<f32>,
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_pad_el: f32,
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};
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@group(0) @binding(0) var<uniform> u: Uniforms;
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// ── Bind group 1: the shared glyph atlas ─────────────────────────────────────
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@group(1) @binding(0) var atlas_tex: texture_2d<f32>;
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@group(1) @binding(1) var atlas_samp: sampler;
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// Draw-order depth bias (see wire.wgsl / image.wgsl).
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const DRAW_ORDER_BIAS: f32 = 0.001;
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// ── Vertex stage ──────────────────────────────────────────────────────────────
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struct VertIn {
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@location(0) pos: vec3<f32>,
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@location(1) pos_low: vec3<f32>,
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@location(2) uv: vec2<f32>,
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@location(3) color: vec4<f32>,
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@location(4) draw_depth: f32,
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};
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struct VertOut {
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@builtin(position) clip_pos: vec4<f32>,
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@location(0) uv: vec2<f32>,
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@location(1) color: vec4<f32>,
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};
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@vertex
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fn vs_main(in: VertIn) -> VertOut {
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var out: VertOut;
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// Double-single relative-to-eye, then rotation-only projection.
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let rel = (in.pos - u.eye_high) + (in.pos_low - u.eye_low);
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out.clip_pos = u.view_rot * vec4<f32>(rel, 1.0);
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out.clip_pos.z = out.clip_pos.z - in.draw_depth * DRAW_ORDER_BIAS * out.clip_pos.w;
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out.uv = in.uv;
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out.color = in.color;
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return out;
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}
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// ── Fragment stage ────────────────────────────────────────────────────────────
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@fragment
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fn fs_main(in: VertOut) -> @location(0) vec4<f32> {
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// SDF value: 0.5 at the glyph edge, higher inside the ink.
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let sd = textureSample(atlas_tex, atlas_samp, in.uv).r;
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// Antialias over one screen-space texel of field change.
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let aa = max(fwidth(sd), 1e-4);
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let a = smoothstep(0.5 - aa, 0.5 + aa, sd);
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if (a <= 0.0) {
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discard;
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}
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return vec4<f32>(in.color.rgb, in.color.a * a);
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}
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