LYGIA Shader Library

kuwahara (lygia/v1.1.6/filter/kuwahara)

Kuwahara image abstraction, drawn from the work of Kyprianidis, et. al. in their publication "Anisotropic Kuwahara Filtering on the GPU" within the GPU Pro collection. This produces an oil-painting-like image, but it is extremely computationally expensive, so it can take seconds to render a frame on an iPad 2. This might be best used for still images.

Dependencies:

Use:

kuwahara(<SAMPLER_TYPE> texture, <vec2> st, <vec2> pixel)

Check it on Github



#ifndef KUWAHARA_TYPE
#define KUWAHARA_TYPE vec4
#endif

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

#ifndef FNC_KUWAHARA
#define FNC_KUWAHARA

#ifdef TARGET_MOBILE
KUWAHARA_TYPE kuwahara(in SAMPLER_TYPE tex, in vec2 st, in vec2 pixel, in int radius) {

    #ifndef KUWAHARA_RADIUS
    #define KUWAHARA_RADIUS radius
    #endif

    float n = float((KUWAHARA_RADIUS + 1) * (KUWAHARA_RADIUS + 1));
    int i; int j;
    KUWAHARA_TYPE m0 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE m1 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE m2 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE m3 = KUWAHARA_TYPE(0.0);
    KUWAHARA_TYPE s0 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE s1 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE s2 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE s3 = KUWAHARA_TYPE(0.0);
    KUWAHARA_TYPE rta = KUWAHARA_TYPE(0.0);
    KUWAHARA_TYPE c = KUWAHARA_TYPE(0.0);

    for (j = -KUWAHARA_RADIUS; j <= 0; ++j)  {
        for (i = -KUWAHARA_RADIUS; i <= 0; ++i)  {
            c = KUWAHARA_SAMPLER_FNC(tex, st + vec2(i,j) * pixel);
            m0 += c;
            s0 += c * c;
        }
    }

    for (j = -KUWAHARA_RADIUS; j <= 0; ++j)  {
        for (i = 0; i <= KUWAHARA_RADIUS; ++i)  {
            c = KUWAHARA_SAMPLER_FNC(tex, st + vec2(i,j) * pixel);
            m1 += c;
            s1 += c * c;
        }
    }

    for (j = 0; j <= KUWAHARA_RADIUS; ++j)  {
        for (i = 0; i <= KUWAHARA_RADIUS; ++i)  {
            c = KUWAHARA_SAMPLER_FNC(tex, st + vec2(i,j) * pixel);
            m2 += c;
            s2 += c * c;
        }
    }

    for (j = 0; j <= KUWAHARA_RADIUS; ++j)  {
        for (i = -KUWAHARA_RADIUS; i <= 0; ++i)  {
            c = KUWAHARA_SAMPLER_FNC(tex, st + vec2(i,j) * pixel);
            m3 += c;
            s3 += c * c;
        }
    }

    float min_sigma2 = 1e+2;
    m0 /= n;
    s0 = abs(s0 / n - m0 * m0);

    float sigma2 = s0.r + s0.g + s0.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m0;
    }

    m1 /= n;
    s1 = abs(s1 / n - m1 * m1);

    sigma2 = s1.r + s1.g + s1.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m1;
    }

    m2 /= n;
    s2 = abs(s2 / n - m2 * m2);

    sigma2 = s2.r + s2.g + s2.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m2;
    }

    m3 /= n;
    s3 = abs(s3 / n - m3 * m3);

    sigma2 = s3.r + s3.g + s3.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m3;
    }

    return rta;
}

#else

KUWAHARA_TYPE kuwahara(in SAMPLER_TYPE tex, in vec2 st, in vec2 pixel, in int radius) {

    #ifndef KUWAHARA_RADIUS

    #if defined(PLATFORM_WEBGL)
    #define KUWAHARA_RADIUS 20
    float n = float((radius + 1) * (radius + 1));
    #else
    #define KUWAHARA_RADIUS radius
    float n = float((KUWAHARA_RADIUS + 1) * (KUWAHARA_RADIUS + 1));
    #endif

    #else
    float n = float((KUWAHARA_RADIUS + 1) * (KUWAHARA_RADIUS + 1));
    #endif

    int i; int j;
    KUWAHARA_TYPE m0 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE m1 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE m2 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE m3 = KUWAHARA_TYPE(0.0);
    KUWAHARA_TYPE s0 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE s1 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE s2 = KUWAHARA_TYPE(0.0); KUWAHARA_TYPE s3 = KUWAHARA_TYPE(0.0);
    KUWAHARA_TYPE rta = KUWAHARA_TYPE(0.0);
    KUWAHARA_TYPE c = KUWAHARA_TYPE(0.0);

    for (j = -KUWAHARA_RADIUS; j <= 0; ++j)  { 
        for (i = -KUWAHARA_RADIUS; i <= 0; ++i)  {
            c = KUWAHARA_SAMPLER_FNC(tex, st + vec2(i,j) * pixel);
            m0 += c;
            s0 += c * c;
        }
    }

    for (j = -KUWAHARA_RADIUS; j <= 0; ++j)  {
        for (i = 0; i <= KUWAHARA_RADIUS; ++i)  {
            #if defined(PLATFORM_WEBGL)
            if (i > radius)
                break;
            #endif
            c = KUWAHARA_SAMPLER_FNC(tex, st + vec2(i,j) * pixel);
            m1 += c;
            s1 += c * c;
        }
    }

    for (j = 0; j <= KUWAHARA_RADIUS; ++j)  {
        #if defined(PLATFORM_WEBGL)
        if (j > radius)
            break;
        #endif
        for (i = 0; i <= KUWAHARA_RADIUS; ++i)  {
            #if defined(PLATFORM_WEBGL)
            if (i > radius)
                break;
            #endif
            c = KUWAHARA_SAMPLER_FNC(tex, st + vec2(i,j) * pixel);
            m2 += c;
            s2 += c * c;
        }
    }

    for (j = 0; j <= KUWAHARA_RADIUS; ++j)  {
        for (i = -KUWAHARA_RADIUS; i <= 0; ++i)  {
            c = KUWAHARA_SAMPLER_FNC(tex, st + vec2(i,j) * pixel);
            m3 += c;
            s3 += c * c;
        }
    }


    float min_sigma2 = 1e+2;
    m0 /= n;
    s0 = abs(s0 / n - m0 * m0);

    float sigma2 = s0.r + s0.g + s0.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m0;
    }

    m1 /= n;
    s1 = abs(s1 / n - m1 * m1);

    sigma2 = s1.r + s1.g + s1.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m1;
    }

    m2 /= n;
    s2 = abs(s2 / n - m2 * m2);

    sigma2 = s2.r + s2.g + s2.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m2;
    }

    m3 /= n;
    s3 = abs(s3 / n - m3 * m3);

    sigma2 = s3.r + s3.g + s3.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m3;
    }

    return rta;
}

#endif

#endif

Dependencies:

Use:

kuwahara(<SAMPLER_TYPE> texture, <float2> st, <float2> pixel)

Check it on Github



#ifndef KUWAHARA_TYPE
#define KUWAHARA_TYPE float4
#endif

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

#ifndef KUWAHARA_RADIUS_MAX
#define KUWAHARA_RADIUS_MAX 15
#endif

#ifndef KUWAHARA_RADIUS
#define KUWAHARA_RADIUS radius
#endif

#ifndef FNC_KUWAHARA
#define FNC_KUWAHARA

KUWAHARA_TYPE kuwahara(in SAMPLER_TYPE tex, in float2 st, in float2 pixel, in int radius) {

    float n = float((KUWAHARA_RADIUS + 1) * (KUWAHARA_RADIUS + 1));
    int i; int j;
    KUWAHARA_TYPE m0 = float4(0.0, 0.0, 0.0, 0.0); KUWAHARA_TYPE m1 = float4(0.0, 0.0, 0.0, 0.0); KUWAHARA_TYPE m2 = float4(0.0, 0.0, 0.0, 0.0); KUWAHARA_TYPE m3 = float4(0.0, 0.0, 0.0, 0.0);
    KUWAHARA_TYPE s0 = float4(0.0, 0.0, 0.0, 0.0); KUWAHARA_TYPE s1 = float4(0.0, 0.0, 0.0, 0.0); KUWAHARA_TYPE s2 = float4(0.0, 0.0, 0.0, 0.0); KUWAHARA_TYPE s3 = float4(0.0, 0.0, 0.0, 0.0);
    KUWAHARA_TYPE rta = float4(0.0, 0.0, 0.0, 0.0);
    KUWAHARA_TYPE c = float4(0.0, 0.0, 0.0, 0.0);

    for (j = -KUWAHARA_RADIUS; j <= 0; ++j)  {
        for (i = -KUWAHARA_RADIUS; i <= 0; ++i)  {
            c = KUWAHARA_SAMPLER_FNC(tex, st + float2(i,j) * pixel);
            m0 += c;
            s0 += c * c;
        }
    }

    for (j = -KUWAHARA_RADIUS; j <= 0; ++j)  {
        for (i = 0; i <= KUWAHARA_RADIUS_MAX; ++i)  {
            if (i > KUWAHARA_RADIUS)
                break;
            c = KUWAHARA_SAMPLER_FNC(tex, st + float2(i,j) * pixel);
            m1 += c;
            s1 += c * c;
        }
    }

    for (j = 0; j <= KUWAHARA_RADIUS_MAX; ++j)  {
        if (j > KUWAHARA_RADIUS)
            break;
        for (i = 0; i <= KUWAHARA_RADIUS_MAX; ++i)  {
            if (i > KUWAHARA_RADIUS)
                break;
            c = KUWAHARA_SAMPLER_FNC(tex, st + float2(i,j) * pixel);
            m2 += c;
            s2 += c * c;
        }
    }

    for (j = 0; j <= KUWAHARA_RADIUS; ++j)  {
        if (j > KUWAHARA_RADIUS)
            break;
        for (i = -KUWAHARA_RADIUS; i <= 0; ++i)  {
            c = KUWAHARA_SAMPLER_FNC(tex, st + float2(i,j) * pixel);
            m3 += c;
            s3 += c * c;
        }
    }


    float min_sigma2 = 1e+2;
    m0 /= n;
    s0 = abs(s0 / n - m0 * m0);

    float sigma2 = s0.r + s0.g + s0.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m0;
    }

    m1 /= n;
    s1 = abs(s1 / n - m1 * m1);

    sigma2 = s1.r + s1.g + s1.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m1;
    }

    m2 /= n;
    s2 = abs(s2 / n - m2 * m2);

    sigma2 = s2.r + s2.g + s2.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m2;
    }

    m3 /= n;
    s3 = abs(s3 / n - m3 * m3);

    sigma2 = s3.r + s3.g + s3.b;
    if (sigma2 < min_sigma2) {
        min_sigma2 = sigma2;
        rta = m3;
    }

    return rta;
}

#endif

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