LYGIA Shader Library

Dependencies:

• lygia/math/const.glsl
• lygia/math/saturate.glsl
• lygia/sample/clamp2edge.glsl

Use:

bilinear(<SAMPLER_TYPE> texture, <vec2> st, <vec2> duv [, <int> kernelSize]])

Check it on Github

#ifndef BILINEAR_TYPE
#define BILINEAR_TYPE vec4
#endif

#ifndef BILINEAR_SAMPLER_FNC
#define BILINEAR_SAMPLER_FNC(TEX, UV) sampleClamp2edge(TEX, UV)
#endif

#ifndef FNC_BILINEAR
#define FNC_BILINEAR
BILINEAR_TYPE bilinear(in sampler2D tex, vec2 st, vec2 pixel, int radius) {
    vec2 coord = st / pixel;
    ivec2 pos = ivec2(floor(coord));
    float R = float(radius);
    BILINEAR_TYPE acc = BILINEAR_TYPE(0.0);
    float normalizationConstant = 3.0 / (PI * R*R);
    for(int y = pos.y - radius; y <= pos.y + radius;++y)
        for(int x = pos.x - radius; x <= pos.x + radius;++x) {
            vec2 xy = vec2(x,y);
            float mag = length(xy-coord);
            float weight = 1.0 - saturate(mag/R);
            acc += weight * BILINEAR_SAMPLER_FNC(tex, xy * pixel);
        }
    return normalizationConstant*acc;
}
#endif