Difference between revisions of "GLSL snippets"
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Revision as of 21:23, 13 December 2019
Ray marching
// http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/ vec3 rayDirection(float fieldOfView, vec2 size, vec2 fragCoord) { vec2 xy = fragCoord - size / 2.0; float z = size.y / tan(radians(fieldOfView) / 2.0); return normalize(vec3(xy, -z)); }
// http://jamie-wong.com/2016/07/15/ray-marching-signed-distance-functions/ float castRay(const int scene, vec3 eye, vec3 dir, float start, float end, float epsilon, int max_marching_steps, out int material) { float depth = start; for (int i = 0; i < max_marching_steps; i++) { float d = sceneSDF(scene, eye + depth * dir, material); if (d < epsilon) return depth; depth += d; if (depth >= end) break; } return end; }
// http://iquilezles.org/www/articles/normalsSDF/normalsSDF.htm vec3 estimateNormal( const int scene, const float epsilon, in vec3 p ) { int m; const vec2 k = vec2(1,-1); return normalize( k.xyy*sceneSDF( scene, p + k.xyy*epsilon, m ) + k.yyx*sceneSDF( scene, p + k.yyx*epsilon, m ) + k.yxy*sceneSDF( scene, p + k.yxy*epsilon, m ) + k.xxx*sceneSDF( scene, p + k.xxx*epsilon, m ) ); }
Matrix transformations
// https://www.khronos.org/registry/OpenGL-Refpages/gl2.1/xhtml/glRotate.xml mat4 rotate(float a, vec3 v) { float c = cos(a); vec3 ci = (1. - c) * v; vec3 s = sin(a) * v; return mat4( ci.x * v.x + c, ci.x * v.y + s.z, ci.x * v.z - s.y, 0, ci.y * v.x - s.z, ci.y * v.y + c, ci.y * v.z + s.x, 0, ci.z * v.x + s.y, ci.z * v.y - s.x, ci.z * v.z + c, 0, 0, 0, 0, 1 ); }
// https://www.khronos.org/registry/OpenGL-Refpages/gl2.1/xhtml/glTranslate.xml mat4 translate(vec3 v) { return mat4( 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, v.x, v.y, v.z, 1 ); }
Noise
// https://stackoverflow.com/questions/12964279/whats-the-origin-of-this-glsl-rand-one-liner float rand(vec2 co) { return fract(sin(dot(co.xy, vec2(12.9898, 78.233))) * 43758.5453); }