volmetrics

annotate data/shaders/vol.f.glsl @ 27:069fae435a1d

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author Eleni Maria Stea <elene.mst@gmail.com>
date Sun, 27 Apr 2014 19:24:48 +0300
parents
children e548d95e0667
rev   line source
elene@25 1 varying vec3 pt;
elene@25 2
elene@25 3 uniform sampler3D tex;
elene@25 4 uniform float tmin;
elene@25 5 uniform float tmax;
elene@25 6 uniform vec3 res;
elene@25 7
elene@25 8 float transfer(float x, float tmin, float tmax)
elene@25 9 {
elene@25 10 float dt = 0.25 * (tmax - tmin);
elene@25 11 return smoothstep(tmin - dt, tmin + dt, x) *
elene@25 12 (1.0 - smoothstep(tmax - dt, tmax + dt, x));
elene@25 13 }
elene@25 14
elene@25 15 vec3 calc_normal(vec3 p, float texel)
elene@25 16 {
elene@25 17 vec3 offs = 1.0 / res;
elene@25 18
elene@25 19 float dfdx = texture3D(tex, p + vec3(offs.x, 0.0, 0.0)).x - texel;
elene@25 20 float dfdy = texture3D(tex, p + vec3(0.0, offs.y, 0.0)).x - texel;
elene@25 21 float dfdz = texture3D(tex, p + vec3(0.0, 0.0, offs.z)).x - texel;
elene@25 22
elene@25 23 return normalize(vec3(dfdx, dfdy, dfdz));
elene@25 24 }
elene@25 25
elene@25 26 void main()
elene@25 27 {
elene@25 28 const vec3 ldir = vec3(-1.0, 1.0, 2.0);
elene@25 29
elene@25 30 if(max(pt.x, max(pt.y, pt.z)) > 1.0 || min(pt.x, min(pt.y, pt.z)) < 0.0)
elene@25 31 discard;
elene@25 32
elene@25 33 float texel = texture3D(tex, pt).x;
elene@25 34 float val = transfer(texel, tmin, tmax);
elene@25 35
elene@25 36 vec3 normal = calc_normal(pt, texel);
elene@25 37 float ndotl = max(dot(normalize(ldir), normal), 0.0);
elene@25 38
elene@25 39 gl_FragColor = vec4(ndotl, ndotl, ndotl, val);
elene@25 40 }