36 lines
No EOL
833 B
Text
36 lines
No EOL
833 B
Text
#include "../math/saturate.msl"
|
|
|
|
/*
|
|
contributors: Inigo Quiles
|
|
description: generate the SDF of s pyramid
|
|
use: <float> pyramidSDF(<float3> p, <float> h )
|
|
*/
|
|
|
|
#ifndef FNC_PYRAMIDSDF
|
|
#define FNC_PYRAMIDSDF
|
|
|
|
float pyramidSDF( float3 p, 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 |