playcanvas/build/playcanvas.dbg/src/scene/shader-lib/wgsl/chunks/common/frag/envAtlas.js

PlayCanvas WebGL game engine

var envAtlasPS = /* wgsl */ `

#ifndef _ENVATLAS_INCLUDED_
#define _ENVATLAS_INCLUDED_

// the envAtlas is fixed at 512 pixels. every equirect is generated with 1 pixel boundary.
const atlasSize : f32 = 512.0;
const seamSize : f32 = 1.0 / atlasSize;

// map a normalized equirect UV to the given rectangle (taking 1 pixel seam into account).
fn mapUv(uv : vec2f, rect : vec4f) -> vec2f {
    return vec2f(mix(rect.x + seamSize, rect.x + rect.z - seamSize, uv.x),
                 mix(rect.y + seamSize, rect.y + rect.w - seamSize, uv.y));
}

// map a normalized equirect UV and roughness level to the correct atlas rect.
fn mapRoughnessUv(uv : vec2f, level : f32) -> vec2f {
    let t : f32 = 1.0 / exp2(level);
    return mapUv(uv, vec4f(0.0, 1.0 - t, t, t * 0.5));
}

// map shiny level UV
fn mapShinyUv(uv : vec2f, level : f32) -> vec2f {
    let t : f32 = 1.0 / exp2(level);
    return mapUv(uv, vec4f(1.0 - t, 1.0 - t, t, t * 0.5));
}

#endif
`;

export { envAtlasPS as default };