  ## pyramidSDF (`lygia`/`sdf`/`pyramidSDF`)

generate the SDF of s pyramid

Dependencies:

Use:

``````<float> pyramidSDF(<vec3> p, <float> h )
``````

Check it on Github

``````

#ifndef FNC_PYRAMIDSDF
#define FNC_PYRAMIDSDF

float pyramidSDF( in vec3 p, in float h )  {
float m2 = h*h + 0.25;

// symmetry
p.xz = abs(p.xz);
p.xz = (p.z>p.x) ? p.zx : p.xz;
p.xz -= 0.5;

// project into face plane (2D)
vec3 q = vec3( p.z, h*p.y - 0.5*p.x, h*p.x + 0.5*p.y);

float s = max(-q.x,0.0);
float t = saturate( (q.y-0.5*p.z)/(m2+0.25) );

float a = m2*(q.x+s)*(q.x+s) + q.y*q.y;
float b = m2*(q.x+0.5*t)*(q.x+0.5*t) + (q.y-m2*t)*(q.y-m2*t);

float d2 = min(q.y,-q.x*m2-q.y*0.5) > 0.0 ? 0.0 : min(a,b);

// recover 3D and scale, and add sign
return sqrt( (d2+q.z*q.z)/m2 ) * sign(max(q.z,-p.y));;
}

#endif
``````

Use:

``````<float> pyramidSDF(<float3> p, <float> h )
``````

Check it on Github

``````
#ifndef FNC_PYRAMIDSDF
#define FNC_PYRAMIDSDF

float pyramidSDF( in float3 p, in float h )  {
float m2 = h*h + 0.25;

// symmetry
p.xz = abs(p.xz);
p.xz = (p.z>p.x) ? p.zx : p.xz;
p.xz -= 0.5;

// project into face plane (2D)
float3 q = float3( p.z, h*p.y - 0.5*p.x, h*p.x + 0.5*p.y);

float s = max(-q.x,0.0);
float t = saturate( (q.y-0.5*p.z)/(m2+0.25) );

float a = m2*(q.x+s)*(q.x+s) + q.y*q.y;
float b = m2*(q.x+0.5*t)*(q.x+0.5*t) + (q.y-m2*t)*(q.y-m2*t);

float d2 = min(q.y,-q.x*m2-q.y*0.5) > 0.0 ? 0.0 : min(a,b);

// recover 3D and scale, and add sign
return sqrt( (d2+q.z*q.z)/m2 ) * sign(max(q.z,-p.y));;
}

#endif
``````