LYGIA Shader Library

aastep (lygia/math/aastep)

Performs a smoothstep using standard derivatives for anti-aliased edges at any level of magnification. From https://github.com/glslify/glsl-aastep

Use:

aastep(<float> threshold, <float> value)

Check it on Github


#ifndef FNC_AASTEP
#define FNC_AASTEP

#if defined(GL_OES_standard_derivatives)
#extension GL_OES_standard_derivatives : enable
#endif

float aastep(float threshold, float value) {
#if !defined(GL_ES) || __VERSION__ >= 300 || defined(GL_OES_standard_derivatives)
    float afwidth = 0.7 * length(vec2(dFdx(value), dFdy(value)));
    return smoothstep(threshold-afwidth, threshold+afwidth, value);
#elif defined(AA_EDGE)
    float afwidth = AA_EDGE;
    return smoothstep(threshold-afwidth, threshold+afwidth, value);
#else 
    return step(threshold, value);
#endif
}
#endif

Use:

aastep(<float> threshold, <float> value)

Check it on Github


#ifndef FNC_AASTEP
#define FNC_AASTEP
float aastep(float compValue, float gradient){
    float halfChange = fwidth(gradient) / 2;
    //base the range of the inverse lerp on the change over one pixel
    float lowerEdge = compValue - halfChange;
    float upperEdge = compValue + halfChange;
    //do the inverse interpolation
    float stepped = (gradient - lowerEdge) / (upperEdge - lowerEdge);
    stepped = saturate(stepped);
    return stepped;
}
#endif


Check it on Github


fn aastep(threshold: f32, value: f32) -> f32 {
    let afwidth = 0.7 * fwidth(value);
    return smoothstep(threshold - afwidth, threshold + afwidth, value);
}

Examples

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