LYGIA Shader Library

Dependencies:

• lygia/sampler.glsl
• lygia/math/const.glsl

Use:

<vec4> smartDeNoise(<sampler2D> tex, <vec2> uv, <vec2> pixel, <float> sigma, <float> kSigma, <float> threshold)

Check it on Github

#ifndef SMARTDENOISE_TYPE
#define SMARTDENOISE_TYPE vec4
#endif

#ifndef SMARTDENOISE_SAMPLER_FNC
#define SMARTDENOISE_SAMPLER_FNC(TEX, UV) SAMPLER_FNC(TEX, UV)
#endif

#ifndef FNC_SMARTDENOISE
#define FNC_SMARTDENOISE

SMARTDENOISE_TYPE smartDeNoise(SAMPLER_TYPE tex, vec2 uv, vec2 pixel, float sigma, float kSigma, float threshold) {
    float radius = floor(kSigma*sigma + 0.5);
    float radQ = radius * radius;

    float invSigmaQx2 = 0.5 / (sigma * sigma);      // 1.0 / (sigma^2 * 2.0)
    float invSigmaQx2PI = INV_PI * invSigmaQx2;    // 1.0 / (sqrt(PI) * sigma)

    float invThresholdSqx2 = 0.5 / (threshold * threshold);  // 1.0 / (sigma^2 * 2.0)
    float invThresholdSqrt2PI = INV_SQRT_TAU / threshold;   // 1.0 / (sqrt(2*PI) * sigma)

    SMARTDENOISE_TYPE centrPx = SMARTDENOISE_SAMPLER_FNC(tex, uv);

    float zBuff = 0.0;
    SMARTDENOISE_TYPE aBuff = SMARTDENOISE_TYPE(0.0);
    for(float x=-radius; x <= radius; x++) {
        // circular kernel
        float pt = sqrt(radQ-x*x);
        for(float y=-pt; y <= pt; y++) {
            vec2 d = vec2(x,y);

            // gaussian factor
            float blurFactor = exp( -dot(d , d) * invSigmaQx2 ) * invSigmaQx2PI; 
            SMARTDENOISE_TYPE walkPx = SMARTDENOISE_SAMPLER_FNC(tex,uv+d*pixel);

            // adaptive
            SMARTDENOISE_TYPE dC = walkPx-centrPx;
            float deltaFactor = exp( -dot(dC, dC) * invThresholdSqx2) * invThresholdSqrt2PI * blurFactor;

            zBuff += deltaFactor;
            aBuff += deltaFactor*walkPx;
        }
    }
    return aBuff/zBuff;
}

#endif