nuclear@0: uniform sampler3D volume;
nuclear@0: uniform sampler2D ray_tex;
nuclear@4: uniform sampler1D xfer_tex;
nuclear@0: 
nuclear@0: struct Ray {
nuclear@0: 	vec3 origin, dir;
nuclear@0: };
nuclear@0: 
nuclear@4: struct AABBox {
nuclear@4: 	vec3 min, max;
nuclear@4: };
nuclear@4: 
nuclear@0: struct ISect {
nuclear@0: 	bool hit;
nuclear@0: 	float t;
nuclear@0: 	vec3 pos;
nuclear@0: 	vec3 normal;
nuclear@0: };
nuclear@0: 
nuclear@1: vec3 sky(Ray ray);
nuclear@0: vec3 ray_march(Ray ray);
nuclear@0: vec3 shade(Ray ray, ISect isect);
nuclear@0: Ray get_primary_ray();
nuclear@4: bool intersect_aabb(Ray ray, AABBox aabb, out float t);
nuclear@0: 
nuclear@0: void main()
nuclear@0: {
nuclear@4: 	const AABBox aabb = AABBox(vec3(0.0, 0.0, 0.0), vec3(1.0, 1.0, 1.0));
nuclear@0: 	Ray ray = get_primary_ray();
nuclear@0: 
nuclear@4: 	vec3 color = vec3(0.0, 0.0, 0.0);
nuclear@4: 
nuclear@4: 	float start_t;
nuclear@4: 	if(intersect_aabb(ray, aabb, start_t)) {
nuclear@4: 		ray.origin += ray.dir * start_t;
nuclear@4: 		color = vec3(1.0, 0.0, 0.0);//ray_march(ray);
nuclear@4: 	}
nuclear@4: 
nuclear@4: 	gl_FragColor = vec4(color, 1.0);
nuclear@0: }
nuclear@0: 
nuclear@1: vec3 sky(Ray ray)
nuclear@0: {
nuclear@0: 	vec3 col1 = vec3(0.75, 0.78, 0.8);
nuclear@0: 	vec3 col2 = vec3(0.56, 0.7, 1.0);
nuclear@0: 
nuclear@0: 	float t = max(ray.dir.y, -0.5);
nuclear@0: 	return mix(col1, col2, t);
nuclear@1: }
nuclear@0: 
nuclear@4: float eval(vec3 pos)
nuclear@4: {
nuclear@4: 	return texture1D(xfer_tex, texture3D(volume, pos).x).x;
nuclear@4: }
nuclear@4: 
nuclear@0: vec3 ray_march(Ray ray)
nuclear@0: {
nuclear@1: 	const float ray_step = 0.1;
nuclear@0: 	float energy = 1.0;
nuclear@0: 	vec3 pos = ray.origin;
nuclear@1: 	float col = 0.0;
nuclear@0: 
nuclear@1: 	for(int i=0; i<40; i++) {
nuclear@4: 		float val = eval(pos) * energy;
nuclear@1: 		col += val;
nuclear@1: 		energy -= val;
nuclear@1: 		if(energy < 0.001) {
nuclear@1: 			break;
nuclear@1: 		}
nuclear@0: 		pos += ray.dir * ray_step;
nuclear@0: 	}
nuclear@0: 
nuclear@1: 	return vec3(col, col, col);
nuclear@0: }
nuclear@0: 
nuclear@0: vec3 shade(Ray ray, ISect isect)
nuclear@0: {
nuclear@0: 	vec3 ldir = normalize(vec3(10.0, 10.0, -10.0) - isect.pos);
nuclear@0: 	vec3 vdir = -ray.dir;
nuclear@0: 	vec3 hdir = normalize(ldir + vdir);
nuclear@0: 
nuclear@0: 	float ndotl = dot(ldir, isect.normal);
nuclear@0: 	float ndoth = dot(hdir, isect.normal);
nuclear@0: 
nuclear@0: 	vec3 dcol = vec3(1.0, 1.0, 1.0) * max(ndotl, 0.0);
nuclear@0: 	vec3 scol = vec3(0.6, 0.6, 0.6) * pow(max(ndoth, 0.0), 50.0);
nuclear@0: 
nuclear@0: 	return vec3(0.01, 0.01, 0.01) + dcol + scol;
nuclear@0: }
nuclear@0: 
nuclear@0: Ray get_primary_ray()
nuclear@0: {
nuclear@0: 	Ray ray;
nuclear@0: 	vec2 tc = gl_TexCoord[0].xy;
nuclear@0: 	ray.dir = gl_NormalMatrix * normalize(texture2D(ray_tex, tc).xyz);
nuclear@0: 	ray.origin = (gl_ModelViewMatrix * vec4(0.0, 0.0, 0.0, 1.0)).xyz;
nuclear@0: 	return ray;
nuclear@0: }
nuclear@4: 
nuclear@4: bool intersect_aabb(Ray ray, AABBox aabb, out float t)
nuclear@4: {
nuclear@4: 	if(ray.origin.x >= aabb.min.x && ray.origin.y >= aabb.min.y && ray.origin.z >= aabb.min.z &&
nuclear@4: 			ray.origin.x < aabb.max.x && ray.origin.y < aabb.max.y && ray.origin.z < aabb.max.z) {
nuclear@4: 		return true;
nuclear@4: 	}
nuclear@4: 
nuclear@4: 	vec4 bbox[2];
nuclear@4: 	bbox[0] = vec4(aabb.min.x, aabb.min.y, aabb.min.z, 0);
nuclear@4: 	bbox[1] = vec4(aabb.max.x, aabb.max.y, aabb.max.z, 0);
nuclear@4: 
nuclear@4: 	int xsign = int(ray.dir.x < 0.0);
nuclear@4: 	float invdirx = 1.0 / ray.dir.x;
nuclear@4: 	float tmin = (bbox[xsign].x - ray.origin.x) * invdirx;
nuclear@4: 	float tmax = (bbox[1 - xsign].x - ray.origin.x) * invdirx;
nuclear@4: 
nuclear@4: 	int ysign = int(ray.dir.y < 0.0);
nuclear@4: 	float invdiry = 1.0 / ray.dir.y;
nuclear@4: 	float tymin = (bbox[ysign].y - ray.origin.y) * invdiry;
nuclear@4: 	float tymax = (bbox[1 - ysign].y - ray.origin.y) * invdiry;
nuclear@4: 
nuclear@4: 	if(tmin > tymax || tymin > tmax) {
nuclear@4: 		return false;
nuclear@4: 	}
nuclear@4: 
nuclear@4: 	if(tymin > tmin) tmin = tymin;
nuclear@4: 	if(tymax < tmax) tmax = tymax;
nuclear@4: 
nuclear@4: 	int zsign = int(ray.dir.z < 0.0);
nuclear@4: 	float invdirz = 1.0 / ray.dir.z;
nuclear@4: 	float tzmin = (bbox[zsign].z - ray.origin.z) * invdirz;
nuclear@4: 	float tzmax = (bbox[1 - zsign].z - ray.origin.z) * invdirz;
nuclear@4: 
nuclear@4: 	if(tmin > tzmax || tzmin > tmax) {
nuclear@4: 		return false;
nuclear@4: 	}
nuclear@4: 
nuclear@4: 	t = tmin;
nuclear@4: 	return tmin < 1.0 && tmax > 0.0;
nuclear@4: }
nuclear@4: