tolelom
6d30151be1
- bloom_shader.wgsl: fullscreen vertex + fs_downsample (5-tap box + bright extract) + fs_upsample (9-tap tent) - tonemap_shader.wgsl: fullscreen vertex + fs_main (HDR+bloom combine, exposure, ACES, gamma 1/2.2) Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
113 lines
4.8 KiB
WebGPU Shading Language
113 lines
4.8 KiB
WebGPU Shading Language
// Bloom pass shader.
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// Two fragment entry points:
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// fs_downsample — 5-tap box filter with optional bright extraction
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// fs_upsample — 9-tap tent filter for the upsample chain
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// ── Group 0 ───────────────────────────────────────────────────────────────────
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@group(0) @binding(0) var t_input: texture_2d<f32>;
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@group(0) @binding(1) var s_input: sampler;
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struct BloomUniform {
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threshold: f32,
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soft_threshold: f32,
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_padding: vec2<f32>,
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};
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@group(0) @binding(2) var<uniform> bloom: BloomUniform;
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// ── Vertex stage ──────────────────────────────────────────────────────────────
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struct VertexInput {
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@location(0) position: vec2<f32>,
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};
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struct VertexOutput {
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@builtin(position) clip_position: vec4<f32>,
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@location(0) uv: vec2<f32>,
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};
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@vertex
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fn vs_main(v: VertexInput) -> VertexOutput {
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var out: VertexOutput;
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out.clip_position = vec4<f32>(v.position, 0.0, 1.0);
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out.uv = vec2<f32>(v.position.x * 0.5 + 0.5, 1.0 - (v.position.y * 0.5 + 0.5));
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return out;
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}
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// ── Shared helpers ────────────────────────────────────────────────────────────
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fn luminance(c: vec3<f32>) -> f32 {
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return dot(c, vec3<f32>(0.2126, 0.7152, 0.0722));
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}
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/// Soft-knee bright-pass: returns the colour with sub-threshold values attenuated.
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fn bright_extract(color: vec3<f32>, threshold: f32, soft: f32) -> vec3<f32> {
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let lum = luminance(color);
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let knee = threshold * soft;
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// Quadratic soft knee
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let ramp = clamp(lum - threshold + knee, 0.0, 2.0 * knee);
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let weight = select(
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select(0.0, 1.0, lum >= threshold),
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ramp * ramp / (4.0 * knee + 0.00001),
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lum >= threshold - knee && lum < threshold,
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);
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// When lum >= threshold we pass through, otherwise fade via weight
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if lum >= threshold {
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return color;
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}
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return color * (weight / max(lum, 0.00001));
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}
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// ── Downsample pass ───────────────────────────────────────────────────────────
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/// 5-sample box filter: centre × 4 + 4 diagonal neighbours × 1, divided by 8.
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/// When bloom.threshold > 0 a bright-pass is applied after filtering.
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@fragment
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fn fs_downsample(in: VertexOutput) -> @location(0) vec4<f32> {
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let uv = in.uv;
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let texel = 1.0 / vec2<f32>(textureDimensions(t_input));
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let center = textureSample(t_input, s_input, uv).rgb;
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let tl = textureSample(t_input, s_input, uv + vec2<f32>(-1.0, -1.0) * texel).rgb;
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let tr = textureSample(t_input, s_input, uv + vec2<f32>( 1.0, -1.0) * texel).rgb;
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let bl = textureSample(t_input, s_input, uv + vec2<f32>(-1.0, 1.0) * texel).rgb;
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let br = textureSample(t_input, s_input, uv + vec2<f32>( 1.0, 1.0) * texel).rgb;
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var color = (center * 4.0 + tl + tr + bl + br) / 8.0;
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// Bright extraction on the first downsample level (threshold guard)
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if bloom.threshold > 0.0 {
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color = bright_extract(color, bloom.threshold, bloom.soft_threshold);
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}
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return vec4<f32>(color, 1.0);
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}
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// ── Upsample pass ─────────────────────────────────────────────────────────────
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/// 9-tap tent filter (3×3):
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/// corners × 1, axis-aligned edges × 2, centre × 4 → /16
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@fragment
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fn fs_upsample(in: VertexOutput) -> @location(0) vec4<f32> {
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let uv = in.uv;
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let texel = 1.0 / vec2<f32>(textureDimensions(t_input));
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let tl = textureSample(t_input, s_input, uv + vec2<f32>(-1.0, -1.0) * texel).rgb;
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let tc = textureSample(t_input, s_input, uv + vec2<f32>( 0.0, -1.0) * texel).rgb;
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let tr = textureSample(t_input, s_input, uv + vec2<f32>( 1.0, -1.0) * texel).rgb;
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let ml = textureSample(t_input, s_input, uv + vec2<f32>(-1.0, 0.0) * texel).rgb;
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let mc = textureSample(t_input, s_input, uv).rgb;
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let mr = textureSample(t_input, s_input, uv + vec2<f32>( 1.0, 0.0) * texel).rgb;
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let bl = textureSample(t_input, s_input, uv + vec2<f32>(-1.0, 1.0) * texel).rgb;
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let bc = textureSample(t_input, s_input, uv + vec2<f32>( 0.0, 1.0) * texel).rgb;
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let br = textureSample(t_input, s_input, uv + vec2<f32>( 1.0, 1.0) * texel).rgb;
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// Tent weights: corners×1 + edges×2 + centre×4 → sum=16
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let color = (tl + tr + bl + br
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+ (tc + ml + mr + bc) * 2.0
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+ mc * 4.0) / 16.0;
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return vec4<f32>(color, 1.0);
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}
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