forked from 1b-agent/opencadstudio-upstream
Hakan Seven
bf4614856c
Keep adaptive sampling in both text shaders with compact sampling loops. Validate shader derivatives and existing text rendering, including GPU pipeline creation. Closes #964
90 lines
3.6 KiB
WebGPU Shading Language
90 lines
3.6 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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let uv_dx = dpdx(in.uv);
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let uv_dy = dpdy(in.uv);
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let dims = vec2<f32>(textureDimensions(atlas_tex));
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let footprint = max(length(uv_dx * dims), length(uv_dy * dims));
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let sd_center = textureSampleLevel(atlas_tex, atlas_samp, in.uv, 0.0).r;
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let aa = max(fwidth(sd_center), 1e-4);
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var alpha = smoothstep(0.5 - aa, 0.5 + aa, sd_center);
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if footprint > 1.0 {
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// Average coverage over the pixel footprint so thin strokes survive minification.
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let samples = select(4, 2, footprint <= 4.0);
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var sum = 0.0;
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for (var y = 0; y < samples; y += 1) {
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for (var x = 0; x < samples; x += 1) {
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let offset = (vec2<f32>(f32(x), f32(y)) + 0.5) / f32(samples) - 0.5;
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let sd = textureSampleLevel(
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atlas_tex, atlas_samp, in.uv + uv_dx * offset.x + uv_dy * offset.y, 0.0
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).r;
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sum += smoothstep(0.5 - aa, 0.5 + aa, sd);
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}
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}
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alpha = sum / f32(samples * samples);
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}
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if alpha <= 0.0 {
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discard;
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}
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return vec4<f32>(in.color.rgb, in.color.a * alpha);
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}
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