volmetrics: data/shaders/vol.f.glsl annotate

volmetrics

conversion to Qt

author	John Tsiombikas <nuclear@member.fsf.org>
date	Fri, 06 Feb 2015 22:39:51 +0200
parents	4b6c952a83bd
children

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@30	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@30	36 vec3 normal = gl_NormalMatrix * 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 }