1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/sdr/volray.p.glsl	Sun Apr 08 07:11:54 2012 +0300
     1.3 @@ -0,0 +1,155 @@
     1.4 +uniform sampler3D volume;
     1.5 +uniform sampler2D ray_tex;
     1.6 +uniform sampler1D xfer_tex;
     1.7 +uniform float ray_step;
     1.8 +uniform float zclip;
     1.9 +
    1.10 +struct Ray {
    1.11 +	vec3 origin, dir;
    1.12 +};
    1.13 +
    1.14 +struct AABBox {
    1.15 +	vec3 min, max;
    1.16 +};
    1.17 +
    1.18 +struct ISect {
    1.19 +	bool hit;
    1.20 +	float t0, t1;
    1.21 +	vec3 pos;
    1.22 +	vec3 normal;
    1.23 +};
    1.24 +
    1.25 +vec3 sky(Ray ray);
    1.26 +vec3 ray_march(Ray ray, float t0, float t1);
    1.27 +vec3 shade(Ray ray, vec3 pos, vec3 norm);
    1.28 +Ray get_primary_ray();
    1.29 +ISect intersect_aabb(Ray ray, AABBox aabb);
    1.30 +
    1.31 +void main()
    1.32 +{
    1.33 +	const AABBox aabb = AABBox(vec3(-1.0, -1.0, -1.0), vec3(1.0, 1.0, 1.0));
    1.34 +	Ray ray = get_primary_ray();
    1.35 +
    1.36 +	vec3 color = vec3(0.0, 0.0, 0.0);
    1.37 +
    1.38 +	ISect res = intersect_aabb(ray, aabb);
    1.39 +	if(res.hit) {
    1.40 +		color = ray_march(ray, res.t0, res.t1);
    1.41 +	}
    1.42 +
    1.43 +	gl_FragColor = vec4(color, 1.0);
    1.44 +}
    1.45 +
    1.46 +float eval(vec3 pos)
    1.47 +{
    1.48 +	vec3 tc = pos * 0.5 + 0.5;
    1.49 +
    1.50 +	if(tc.x < 0.0 || tc.y < 0.0 || tc.z < zclip || tc.x > 1.0 || tc.y > 1.0 || tc.z > 1.0) {
    1.51 +		return 0.0;
    1.52 +	}
    1.53 +
    1.54 +	return texture1D(xfer_tex, texture3D(volume, tc).a).x;
    1.55 +}
    1.56 +
    1.57 +#define OFFS	0.01
    1.58 +vec3 ray_march(Ray ray, float t0, float t1)
    1.59 +{
    1.60 +	float energy = 1.0;
    1.61 +	float t = t0;
    1.62 +	vec3 col = vec3(0.0, 0.0, 0.0);
    1.63 +
    1.64 +
    1.65 +	while(t < t1) {
    1.66 +		vec3 pos = ray.origin + ray.dir * t;
    1.67 +		t += ray_step;
    1.68 +
    1.69 +		float val = eval(pos);
    1.70 +		vec3 norm;
    1.71 +
    1.72 +		norm.x = eval(pos + vec3(OFFS, 0.0, 0.0)) - val;
    1.73 +		norm.y = eval(pos + vec3(0.0, OFFS, 0.0)) - val;
    1.74 +		norm.z = eval(pos + vec3(0.0, 0.0, OFFS)) - val;
    1.75 +
    1.76 +		col += shade(ray, pos, normalize(norm)) * val * energy;
    1.77 +		energy -= val;
    1.78 +		if(energy < 0.001) {
    1.79 +			break;
    1.80 +		}
    1.81 +		pos += ray.dir * ray_step;
    1.82 +	}
    1.83 +
    1.84 +	return col;
    1.85 +}
    1.86 +
    1.87 +vec3 shade(Ray ray, vec3 pos, vec3 norm)
    1.88 +{
    1.89 +	vec3 ldir = -pos;//normalize(vec3(10.0, 10.0, -10.0) - pos);
    1.90 +	vec3 vdir = -ray.dir;
    1.91 +	vec3 hdir = normalize(ldir + vdir);
    1.92 +
    1.93 +	float ndotl = dot(ldir, norm);
    1.94 +	float ndoth = dot(hdir, norm);
    1.95 +
    1.96 +	vec3 dcol = vec3(0.9, 0.9, 0.9) * max(ndotl, 0.0);
    1.97 +	vec3 scol = vec3(0.5, 0.5, 0.5) * pow(max(ndoth, 0.0), 50.0);
    1.98 +
    1.99 +	return vec3(0.01, 0.01, 0.01) + dcol + scol;
   1.100 +}
   1.101 +
   1.102 +Ray get_primary_ray()
   1.103 +{
   1.104 +	Ray ray;
   1.105 +	vec2 tc = gl_TexCoord[0].xy;
   1.106 +	ray.dir = gl_NormalMatrix * normalize(texture2D(ray_tex, tc).xyz);
   1.107 +	ray.origin = (gl_ModelViewMatrix * vec4(0.0, 0.0, 0.0, 1.0)).xyz;
   1.108 +	return ray;
   1.109 +}
   1.110 +
   1.111 +ISect intersect_aabb(Ray ray, AABBox aabb)
   1.112 +{
   1.113 +	ISect res;
   1.114 +	res.hit = false;
   1.115 +	res.t0 = res.t1 = 0.0;
   1.116 +
   1.117 +	if(ray.origin.x >= aabb.min.x && ray.origin.y >= aabb.min.y && ray.origin.z >= aabb.min.z &&
   1.118 +			ray.origin.x < aabb.max.x && ray.origin.y < aabb.max.y && ray.origin.z < aabb.max.z) {
   1.119 +		res.hit = true;
   1.120 +		return res;
   1.121 +	}
   1.122 +
   1.123 +	vec4 bbox[2];
   1.124 +	bbox[0] = vec4(aabb.min.x, aabb.min.y, aabb.min.z, 0);
   1.125 +	bbox[1] = vec4(aabb.max.x, aabb.max.y, aabb.max.z, 0);
   1.126 +
   1.127 +	int xsign = int(ray.dir.x < 0.0);
   1.128 +	float invdirx = 1.0 / ray.dir.x;
   1.129 +	float tmin = (bbox[xsign].x - ray.origin.x) * invdirx;
   1.130 +	float tmax = (bbox[1 - xsign].x - ray.origin.x) * invdirx;
   1.131 +
   1.132 +	int ysign = int(ray.dir.y < 0.0);
   1.133 +	float invdiry = 1.0 / ray.dir.y;
   1.134 +	float tymin = (bbox[ysign].y - ray.origin.y) * invdiry;
   1.135 +	float tymax = (bbox[1 - ysign].y - ray.origin.y) * invdiry;
   1.136 +
   1.137 +	if(tmin > tymax || tymin > tmax) {
   1.138 +		return res;
   1.139 +	}
   1.140 +
   1.141 +	if(tymin > tmin) tmin = tymin;
   1.142 +	if(tymax < tmax) tmax = tymax;
   1.143 +
   1.144 +	int zsign = int(ray.dir.z < 0.0);
   1.145 +	float invdirz = 1.0 / ray.dir.z;
   1.146 +	float tzmin = (bbox[zsign].z - ray.origin.z) * invdirz;
   1.147 +	float tzmax = (bbox[1 - zsign].z - ray.origin.z) * invdirz;
   1.148 +
   1.149 +	if(tmin > tzmax || tzmin > tmax) {
   1.150 +		return res;
   1.151 +	}
   1.152 +
   1.153 +	res.t0 = tmin;
   1.154 +	res.t1 = tmax;
   1.155 +	res.hit = true;
   1.156 +	return res;
   1.157 +}
   1.158 +