playcanvas/build/playcanvas.dbg/src/scene/shader-lib/glsl/chunks/gsplat/vert/gsplatData.js

PlayCanvas WebGL game engine

var gsplatDataVS = /* glsl */ `
uniform highp usampler2D transformA;
uniform highp sampler2D transformB;

// work values
uint tAw;

// read the model-space center of the gaussian
vec3 readCenter(SplatSource source) {
    // read transform data
    uvec4 tA = texelFetch(transformA, source.uv, 0);
    tAw = tA.w;
    return uintBitsToFloat(tA.xyz);
}

vec4 unpackRotation(vec3 packed) {
    return vec4(packed.xyz, sqrt(max(0.0, 1.0 - dot(packed, packed))));
}

// sample covariance vectors
void readCovariance(in SplatSource source, out vec3 covA, out vec3 covB) {
    vec4 tB = texelFetch(transformB, source.uv, 0);

    mat3 rot = quatToMat3(unpackRotation(vec3(unpackHalf2x16(tAw), tB.w)).wxyz);
    vec3 scale = tB.xyz;
    
    // M = S * R
    mat3 M = transpose(mat3(
        scale.x * rot[0],
        scale.y * rot[1],
        scale.z * rot[2]
    ));

    covA = vec3(dot(M[0], M[0]), dot(M[0], M[1]), dot(M[0], M[2]));
    covB = vec3(dot(M[1], M[1]), dot(M[1], M[2]), dot(M[2], M[2]));
}
`;

export { gsplatDataVS as default };