# LYGIA Shader Library

## kochSDF (`lygia`/`sdf`/`kochSDF`)

Returns a Koch curve SDF.

Dependencies:

Use:

``````<vec2> kochSDF(<vec2> st, <int> iterations)
``````

Check it on Github

``````

#ifndef FNC_KOCHSDF
#define FNC_KOCHSDF
float kochSDF( vec2 st, vec2 center, int N ) {
st -= center;
st *= 3.0;
float r3 = sqrt(3.);
st = abs(st);
st += r3*vec2(-st.y,st.x); // 60° rotation, scale 2
st.y -= 1.;
float w = .5;
mat2 m = mat2(r3,3,-3,r3)*.5;
#ifdef PLATFORM_WEBGL
for (int i = 0; i< 20; i++) {
if (i >= N) break;
#else
for (int i = 0; i< N; i++) {
#endif
st = vec2(-r3,3)*.5 - m*vec2(st.y,abs(st.x));
w /= r3;
}
float d = sign(st.y)*length(vec2(st.y,max(0.,abs(st.x)-r3)));
return (d*w);
}

float kochSDF( vec2 st, int N ) {
#ifdef CENTER_2D
return kochSDF(st, CENTER_2D, N);
#else
return kochSDF(st, vec2(0.5), N);
#endif
}
#endif
``````

Dependencies:

Use:

``````<float2> kochSDF(<float2> st, <int> iterations)
``````

Check it on Github

``````

#ifndef FNC_KOCHSDF
#define FNC_KOCHSDF
float kochSDF( float2 st, float2 center, int N ) {
st -= center;
st *= 3.0;
float r3 = sqrt(3.);
st = abs(st);
st += r3*float2(-st.y,st.x); // 60° rotation, scale 2
st.y -= 1.;
float w = .5;
float2x2 m = float2x2(r3,3,-3,r3)*.5;
for (int i = 0; i< N; i++) {
st = float2(-r3,3)*.5 - m*float2(st.y,abs(st.x));
w /= r3;
}
float d = sign(st.y)*length(float2(st.y,max(0.,abs(st.x)-r3)));
return (d*w);
}

float kochSDF( float2 st, int N ) {
#ifdef CENTER_2D
return kochSDF(st, CENTER_2D, N);
#else
return kochSDF(st, float2(0.5, 0.5), N);
#endif
}
#endif
``````

## License

LYGIA is dual-licensed under the Prosperity License and the Patron License for sponsors and contributors.

Sponsors and contributors are automatically added to the Patron License and they can ignore the any non-commercial rule of the Prosperity Licensed software (please take a look to the exception).

It's also possible to get a permanent comercial license hook to a single and specific version of LYGIA.

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