# LYGIA Shader Library

## rectSDF (`lygia`/`sdf`/`rectSDF`)

Returns a rectangular SDF

Use:

``````rectSDF(<vec2> st [, <vec2|float> size])
``````
``````rectSDF(<vec2> st [, <vec2|float> size, float radius])
``````

Check it on Github

``````
#ifndef FNC_RECTSDF
#define FNC_RECTSDF

float rectSDF(vec2 p, vec2 b, float r) {
vec2 d = abs(p - 0.5) * 4.2 - b + vec2(r);
return min(max(d.x, d.y), 0.0) + length(max(d, 0.0)) - r;
}

float rectSDF(vec2 p, float b, float r) {
return rectSDF(p, vec2(b), r);
}

float rectSDF(in vec2 st, in vec2 s) {
#ifdef CENTER_2D
st -= CENTER_2D;
st *= 2.0;
#else
st = st * 2.0 - 1.0;
#endif
return max( abs(st.x / s.x),
abs(st.y / s.y) );
}

float rectSDF(in vec2 st, in float s) {
return rectSDF(st, vec2(s) );
}

float rectSDF(in vec2 st) {
return rectSDF(st, vec2(1.0));
}

#endif

``````

Use:

``````rectSDF(<float2> st, <float2> size)
``````

Check it on Github

``````
#ifndef FNC_RECTSDF
#define FNC_RECTSDF
float rectSDF(float2 p, float2 b, float r) {
float2 d = abs(p - 0.5) * 4.2 - b + float2(r, r);
return min(max(d.x, d.y), 0.0) + length(max(d, 0.0)) - r;
}

float rectSDF(float2 p, float b, float r) {
return rectSDF(p, float2(b, b), r);
}

float rectSDF(in float2 st, in float2 s) {
#ifdef CENTER_2D
st -= CENTER_2D;
st *= 2.0;
#else
st = st * 2.0 - 1.0;
#endif
return max( abs(st.x / s.x),
abs(st.y / s.y) );
}

float rectSDF(in float2 st, in float s) {
return rectSDF(st, float2(s, s) );
}

float rectSDF(in float2 st) {
return rectSDF(st, float2(1.0, 1.0));
}
#endif

``````

Check it on Github

``````
fn rectSDF_round(p: vec2f , b: vec2f, r: f32) -> f32 {
let d = abs(p - 0.5) * 4.2 - b + r;
return min(max(d.x, d.y), 0.0) + length(vec2f( max(d.x, 0.0), max(d.y, 0.0) )) - r;
}

fn rectSDF(st: vec2f, s: vec2f) -> f32 {
let uv = st * 2.0 - 1.0;
return max( abs(uv.x / s.x),
abs(uv.y / s.y) );
}
``````