Fragment Shader with Noise Issues

bg_fs.essl

Shader.source[document.currentScript.src.split('js/shaders/')[1]] = `
    precision highp float;

    varying vec3 rayDir;

    uniform vec3 eyePos;
    uniform samplerCube envmapTexture;

    uniform mat4 quadrics[32];
    uniform vec4 brdfs[16];
    uniform vec4 lightPositions[8];
    uniform vec4 lightPowerDensities[8];

    float intersectClippedQuadric(mat4 A, mat4 B, vec4 e, vec4 d) {
        float a = dot(d * A, d);
        float b = dot(d * A, e) + dot(e * A, d);
        float c = dot(e * A, e);

        float disc = b*b-4.0*a*c;

        if(disc < 0.0) {
            return -1.0;
        }

        float t1 = (-1.0*b + sqrt(disc))/(2.0*a);
        float t2 = (-1.0*b - sqrt(disc))/(2.0*a);

        vec4 r1 = e + d * t1;
        vec4 r2 = e + d * t2;

        if(dot(r1 * B, r1) > 0.0) {
            t1 = -1.0;
        }

        if(dot(r2 * B, r2) > 0.0) {
            t2 = -1.0;
        }

        if(t1 > 0.0 && t1 < t2) return t1;
        if(t2 > 0.0 && t2 < t1) return t2;
        if(t1 > 0.0) return t1;
        return t2;
    }

    bool findBestHit(vec4 e, vec4 d,
    out float bestT, out vec4 bestBrdf, out mat4 bestA) {
        bestA = quadrics[1];
        bestBrdf = brdfs[1];
        // bestT = 5.0;
        // return true;
        bestT = 9000.0;

        for(int i=0; i<16; i++) {
            float currentT = intersectClippedQuadric(quadrics[i*2], quadrics[i*2+1], e, d);

            if(currentT < bestT && currentT > 0.0) {
                bestT = currentT;
                bestBrdf = brdfs[i];
                bestA = quadrics[i*2];
            }
        }

        if(bestT < 9000.0) {
            return true;
        }
        return false;
    }

    void main(void) {
        vec4 e = vec4(eyePos, 1);
        vec4 d = vec4(normalize(rayDir), 0);


        vec3 contrib = vec3(1, 1, 1);
        vec4 color = vec4(0, 0, 0, 0);
        for(int i=0; i<5; i++) {
            float t; vec4 brdf; mat4 a;
            bool hitFound = findBestHit(e, d, t, brdf, a);
            if(!hitFound) {
                color += textureCube(envmapTexture, d.xyz);
                break;
            } else {
                color += vec4(brdf.xyz, 1) * vec4(contrib, 1);
                contrib *= brdf.rgb;
                e = e + d*t;
                d = vec4(normalize((e*a+e*a).xyz), 0);

                if(contrib.r < 0.1 && contrib.g < 0.1 && contrib.b < 0.1) {
                    break;
                }
            }
        }
        gl_FragColor = vec4(color.rgb, 1);
    }
`;