@animech-public/playcanvas/build/playcanvas.dbg/src/scene/shader-lib/chunks/lit/frag/shadowVSM_common.js

PlayCanvas WebGL game engine

var shadowVSM_commonPS = /* glsl */`
float linstep(float a, float b, float v) {
    return saturate((v - a) / (b - a));
}

float reduceLightBleeding(float pMax, float amount) {
   // Remove the [0, amount] tail and linearly rescale (amount, 1].
   return linstep(amount, 1.0, pMax);
}

float chebyshevUpperBound(vec2 moments, float mean, float minVariance, float lightBleedingReduction) {
    // Compute variance
    float variance = moments.y - (moments.x * moments.x);
    variance = max(variance, minVariance);

    // Compute probabilistic upper bound
    float d = mean - moments.x;
    float pMax = variance / (variance + (d * d));

    pMax = reduceLightBleeding(pMax, lightBleedingReduction);

    // One-tailed Chebyshev
    return (mean <= moments.x ? 1.0 : pMax);
}

float calculateEVSM(vec3 moments, float Z, float vsmBias, float exponent) {
    Z = 2.0 * Z - 1.0;
    float warpedDepth = exp(exponent * Z);

    moments.xy += vec2(warpedDepth, warpedDepth*warpedDepth) * (1.0 - moments.z);

    float VSMBias = vsmBias;//0.01 * 0.25;
    float depthScale = VSMBias * exponent * warpedDepth;
    float minVariance1 = depthScale * depthScale;
    return chebyshevUpperBound(moments.xy, warpedDepth, minVariance1, 0.1);
}
`;

export { shadowVSM_commonPS as default };