playcanvas/build/playcanvas.dbg/src/scene/shader-lib/wgsl/chunks/render-pass/frag/compose/compose-cas.js

Open-source WebGL/WebGPU 3D engine for the web

// Contrast Adaptive Sharpening (CAS) is used to apply the sharpening. It's based on AMD's
// FidelityFX CAS, WebGL implementation: https://www.shadertoy.com/view/wtlSWB. It's best to run it
// on a tone-mapped color buffer after post-processing, but before the UI, and so this is the
// obvious place to put it to avoid a separate render pass, even though we need to handle running it
// before the tone-mapping.
var composeCasPS = /* wgsl */ `
    #ifdef CAS
        uniform sharpness: f32;

        // reversible LDR <-> HDR tone mapping, as CAS needs LDR input
        #ifdef CAS_HDR
            fn maxComponent(x: f32, y: f32, z: f32) -> f32 { return max(x, max(y, z)); }
            fn toSDR(c: vec3f) -> vec3f { return c / (1.0 + maxComponent(c.r, c.g, c.b)); }
            fn toHDR(c: vec3f) -> vec3f { return c / max(1.0 - maxComponent(c.r, c.g, c.b), 1e-4); }
        #else
            fn toSDR(c: vec3f) -> vec3f { return c; }
            fn toHDR(c: vec3f) -> vec3f { return c; }
        #endif

        fn applyCas(color: vec3f, uv: vec2f, sharpness: f32) -> vec3f {
            let x = uniform.sceneTextureInvRes.x;
            let y = uniform.sceneTextureInvRes.y;

            // sample 4 neighbors around the already sampled pixel, and convert it to SDR
            let a: half3 = half3(toSDR(textureSampleLevel(sceneTexture, sceneTextureSampler, uv + vec2f(0.0, -y), 0.0).rgb));
            let b: half3 = half3(toSDR(textureSampleLevel(sceneTexture, sceneTextureSampler, uv + vec2f(-x, 0.0), 0.0).rgb));
            let c: half3 = half3(toSDR(color.rgb));
            let d: half3 = half3(toSDR(textureSampleLevel(sceneTexture, sceneTextureSampler, uv + vec2f(x, 0.0), 0.0).rgb));
            let e: half3 = half3(toSDR(textureSampleLevel(sceneTexture, sceneTextureSampler, uv + vec2f(0.0, y), 0.0).rgb));

            // apply the sharpening
            let min_g = min(a.g, min(b.g, min(c.g, min(d.g, e.g))));
            let max_g = max(a.g, max(b.g, max(c.g, max(d.g, e.g))));
            let sharpening_amount = sqrt(min(half(1.0) - max_g, min_g) / max(max_g, half(1e-4)));
            let w = sharpening_amount * half(sharpness);
            var res = (w * (a + b + d + e) + c) / (half(4.0) * w + half(1.0));

            // remove negative colors
            res = max(res, half3(0.0));

            // convert back to HDR
            return toHDR(vec3f(res));
        }
    #endif
`;

export { composeCasPS as default };