playcanvas/build/playcanvas.dbg/src/scene/shader-lib/wgsl/chunks/lit/frag/clusteredLightUtils.js

PlayCanvas WebGL game engine

var clusteredLightUtilsPS = /* wgsl */ `
struct FaceCoords {
    uv: vec2f,          // Original return value
    faceIndex: f32,    // Was out parameter
    tileOffset: vec2f, // Was out parameter
}

// Converts unnormalized direction vector to a cubemap face index [0..5] and uv coordinates within the face in [0..1] range.
// Additionally offset to a tile in atlas within 3x3 subdivision is provided
fn getCubemapFaceCoordinates(dir: vec3f) -> FaceCoords {
    var faceIndex: f32;
    var tileOffset: vec2f;
    var uv: vec2f; // This is the face UV [0..1]
    let vAbs: vec3f = abs(dir);
    var ma: f32;

    if (vAbs.z >= vAbs.x && vAbs.z >= vAbs.y) {   // front / back

        let is_neg_z = dir.z < 0.0;
        faceIndex = select(4.0, 5.0, is_neg_z);
        ma = 0.5 / vAbs.z;
        uv = vec2f(select(dir.x, -dir.x, is_neg_z), -dir.y);
        tileOffset = vec2f(2.0, select(0.0, 1.0, is_neg_z));

    } else if (vAbs.y >= vAbs.x) {  // top index 2, bottom index 3

        let is_neg_y = dir.y < 0.0;
        faceIndex = select(2.0, 3.0, is_neg_y);
        ma = 0.5 / vAbs.y;
        uv = vec2f(dir.x, select(dir.z, -dir.z, is_neg_y));
        tileOffset = vec2f(1.0, select(0.0, 1.0, is_neg_y));

    } else {    // left / right

        let is_neg_x = dir.x < 0.0;
        faceIndex = select(0.0, 1.0, is_neg_x);
        ma = 0.5 / vAbs.x;
        uv = vec2f(select(-dir.z, dir.z, is_neg_x), -dir.y);
        tileOffset = vec2f(0.0, select(0.0, 1.0, is_neg_x));
    }

    uv = uv * ma + 0.5;
    return FaceCoords(uv, faceIndex, tileOffset);
}

// converts unnormalized direction vector to a texture coordinate for a cubemap face stored within texture atlas described by the viewport
fn getCubemapAtlasCoordinates(omniAtlasViewport: vec3f, shadowEdgePixels: f32, shadowTextureResolution: f32, dir: vec3f) -> vec2f {

    let faceData: FaceCoords = getCubemapFaceCoordinates(dir);
    var uv: vec2f = faceData.uv;
    let tileOffset: vec2f = faceData.tileOffset;

    // move uv coordinates inwards inside to compensate for larger fov when rendering shadow into atlas
    let atlasFaceSize: f32 = omniAtlasViewport.z;
    let tileSize: f32 = shadowTextureResolution * atlasFaceSize;
    var offset: f32 = shadowEdgePixels / tileSize;
    uv = uv * (1.0 - offset * 2.0) + offset;

    // scale uv coordinates to cube face area within the viewport
    uv = uv * atlasFaceSize;

    // offset into face of the atlas (3x3 grid)
    uv = uv + tileOffset * atlasFaceSize;

    // offset into the atlas viewport
    uv = uv + omniAtlasViewport.xy;

    return uv;
}
`;

export { clusteredLightUtilsPS as default };