nuclear@0: /* vim: set ft=glsl:ts=4:sw=4 */
nuclear@0: uniform vec4 seed;
nuclear@0: uniform sampler2D ray_tex;
nuclear@0: uniform float err_thres;
nuclear@0: uniform int iter;
nuclear@0: 
nuclear@0: #define quat(s, x, y, z)	vec4(x, y, z, s)
nuclear@0: #define quat_identity()		vec4(0.0, 0.0, 0.0, 1.0)
nuclear@0: 
nuclear@0: #define vec2quat(v)		(v).wxyz
nuclear@0: 
nuclear@0: struct Ray {
nuclear@0: 	vec3 origin;
nuclear@0: 	vec3 dir;
nuclear@0: };
nuclear@0: 
nuclear@0: struct Julia {
nuclear@0: 	bool inside;
nuclear@0: 	vec4 q;
nuclear@0: 	vec4 qprime;
nuclear@0: };
nuclear@0: 
nuclear@0: struct ISect {
nuclear@0: 	bool hit;
nuclear@0: 	float t;
nuclear@0: 	vec3 pos;
nuclear@0: 	vec3 normal;
nuclear@0: 	vec3 color;
nuclear@0: 	float kr;
nuclear@0: };
nuclear@0: 
nuclear@0: ISect find_intersection(Ray ray);
nuclear@0: vec3 shade(Ray ray, ISect isect);
nuclear@0: float amboc(ISect isect);
nuclear@0: vec3 sky(Ray ray);
nuclear@0: Julia julia(vec4 q, vec4 c);
nuclear@0: float julia_dist(vec4 z);
nuclear@0: vec3 julia_grad(vec4 z);
nuclear@0: vec4 quat_mul(vec4 q1, vec4 q2);
nuclear@0: vec4 quat_sq(vec4 q);
nuclear@0: float quat_length_sq(vec4 q);
nuclear@0: ISect ray_julia(Ray ray);
nuclear@0: ISect ray_sphere(Ray ray, float rad);
nuclear@0: ISect ray_floor(Ray ray);
nuclear@0: Ray get_primary_ray();
nuclear@0: 
nuclear@0: 
nuclear@0: void main()
nuclear@0: {
nuclear@0: 	Ray ray = get_primary_ray();
nuclear@0: 
nuclear@0: 	float energy = 1.0;
nuclear@0: 	vec3 color = vec3(0.0, 0.0, 0.0);
nuclear@0: 
nuclear@0: 	while(energy > 0.001) {
nuclear@0: 		ISect res = find_intersection(ray);
nuclear@0: 
nuclear@0: 		if(res.hit) {
nuclear@0: 			color += shade(ray, res) * energy;
nuclear@0: 			energy *= res.kr;
nuclear@0: 
nuclear@0: 			ray.origin = res.pos;
nuclear@0: 			ray.dir = reflect(ray.dir, res.normal);
nuclear@0: 		} else {
nuclear@0: 			color += sky(ray) * energy;
nuclear@0: 			break;
nuclear@0: 		}
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	gl_FragColor = vec4(color, 1.0);
nuclear@0: }
nuclear@0: 
nuclear@0: 
nuclear@0: ISect find_intersection(Ray ray)
nuclear@0: {
nuclear@0: 	ISect res;
nuclear@0: 	res.hit = false;
nuclear@0: 	
nuclear@0: 	ISect bhit = ray_sphere(ray, 2.0);
nuclear@0: 	if(bhit.hit) {
nuclear@0: 		ray.origin = bhit.pos;
nuclear@0: 		res = ray_julia(ray);
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	if(!res.hit) {
nuclear@0: 		res = ray_floor(ray);
nuclear@0: 	}
nuclear@0: 	return res;
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 = /*isect.color * max(ndotl, 0.0) */ amboc(isect);
nuclear@0: 	vec3 scol = vec3(1.0, 1.0, 1.0) * pow(max(ndoth, 0.0), 40.0);
nuclear@0: 
nuclear@0: 	return /*vec3(0.05, 0.05, 0.05) + */dcol;// + scol;
nuclear@0: }
nuclear@0: 
nuclear@0: #define AO_STEP		0.04
nuclear@0: #define AO_MAGIC	8.0
nuclear@0: float amboc(ISect isect)
nuclear@0: {
nuclear@0: 	float sum = 0.0;
nuclear@0: 
nuclear@0: 	for(float fi=0.0; fi<5.0; fi+=1.0) {
nuclear@0: 		float sample_dist = fi * AO_STEP;
nuclear@0: 		vec3 pt = isect.pos + isect.normal * sample_dist;
nuclear@0: 		float jdist = julia_dist(quat(pt.x, pt.y, pt.z, 0.0));
nuclear@0: 
nuclear@0: 		sum += 1.0 / pow(2.0, fi) * (sample_dist - jdist);
nuclear@0: 	}
nuclear@0: 	
nuclear@0: 	return 1.0 - AO_MAGIC * sum;
nuclear@0: }
nuclear@0: 
nuclear@0: 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@0: }
nuclear@0: 
nuclear@0: Julia julia(vec4 q, vec4 c)
nuclear@0: {
nuclear@0: 	Julia res;
nuclear@0: 	res.inside = true;
nuclear@0: 
nuclear@0: 	res.q = q;
nuclear@0: 	res.qprime = quat_identity();
nuclear@0: 
nuclear@0: 	for(int i=0; i<iter; i++) {
nuclear@0: 		res.qprime = 2.0 * quat_mul(res.q, res.qprime);
nuclear@0: 		res.q = quat_sq(res.q) + c;
nuclear@0: 
nuclear@0: 		if(dot(res.q, res.q) > 8.0) {
nuclear@0: 			res.inside = false;
nuclear@0: 			break;
nuclear@0: 		}
nuclear@0: 	}
nuclear@0: 	return res;
nuclear@0: }
nuclear@0: 
nuclear@0: float julia_dist(vec4 z)
nuclear@0: {
nuclear@0: 	Julia jres = julia(z, seed);
nuclear@0: 
nuclear@0: 	float lenq = length(jres.q);
nuclear@0: 	float lenqprime = length(jres.qprime);
nuclear@0: 
nuclear@0: 	return 0.5 * lenq * log(lenq) / lenqprime;
nuclear@0: }
nuclear@0: 
nuclear@0: #define OFFS 1e-4
nuclear@0: vec3 julia_grad(vec4 z)
nuclear@0: {
nuclear@0: 	vec3 grad;
nuclear@0: 	grad.x = julia_dist(z + quat(OFFS, 0.0, 0.0, 0.0)) - julia_dist(z - quat(OFFS, 0.0, 0.0, 0.0));
nuclear@0: 	grad.y = julia_dist(z + quat(0.0, OFFS, 0.0, 0.0)) - julia_dist(z - quat(0.0, OFFS, 0.0, 0.0));
nuclear@0: 	grad.z = julia_dist(z + quat(0.0, 0.0, OFFS, 0.0)) - julia_dist(z - quat(0.0, 0.0, OFFS, 0.0));
nuclear@0: 	return grad;
nuclear@0: }
nuclear@0: 
nuclear@0: vec4 quat_mul(vec4 q1, vec4 q2)
nuclear@0: {
nuclear@0: 	vec4 res;
nuclear@0: 	res.w = q1.w * q2.w - dot(q1.xyz, q2.xyz);
nuclear@0: 	res.xyz = q1.w * q2.xyz + q2.w * q1.xyz + cross(q1.xyz, q2.xyz);
nuclear@0: 	return res;
nuclear@0: }
nuclear@0: 
nuclear@0: vec4 quat_sq(vec4 q)
nuclear@0: {
nuclear@0: 	vec4 res;
nuclear@0: 	res.w = q.w * q.w - dot(q.xyz, q.xyz);
nuclear@0: 	res.xyz = 2.0 * q.w * q.xyz;
nuclear@0: 	return res;
nuclear@0: }
nuclear@0: 
nuclear@0: ISect ray_julia(Ray inray)
nuclear@0: {
nuclear@0: 	float dist_acc = 0.0;
nuclear@0: 	Ray ray = inray;
nuclear@0: 	ISect res;
nuclear@0: 
nuclear@0: 	for(float fi=0.0; ; fi+=0.1) {
nuclear@0: 		vec4 q = quat(ray.origin.x, ray.origin.y, ray.origin.z, 0.0);
nuclear@0: 		
nuclear@0: 		float dist = julia_dist(q);
nuclear@0: 
nuclear@0: 		ray.origin += ray.dir * dist;
nuclear@0: 		dist_acc += dist;
nuclear@0: 
nuclear@0: 		if(dist < err_thres) {
nuclear@0: 			res.hit = true;
nuclear@0: 			res.t = dist_acc;
nuclear@0: 			res.pos = ray.origin;
nuclear@0: 			res.normal = normalize(julia_grad(quat(res.pos.x, res.pos.y, res.pos.z, 0.0)));
nuclear@0: 			res.color = vec3(0.75, 0.8, 0.9);//abs(res.normal) * 0.2;
nuclear@0: 			//res.kr = 0.6;
nuclear@0: 			res.kr = 0.0;
nuclear@0: 			break;
nuclear@0: 		}
nuclear@0: 
nuclear@0: 		if(dot(ray.origin, ray.origin) > 100.0) {
nuclear@0: 			res.hit = false;
nuclear@0: 			break;
nuclear@0: 		}
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	return res;
nuclear@0: }
nuclear@0: 
nuclear@0: ISect ray_sphere(Ray ray, float rad)
nuclear@0: {
nuclear@0: 	ISect res;
nuclear@0: 	res.hit = false;
nuclear@0: 
nuclear@0: 	float a = dot(ray.dir, ray.dir);
nuclear@0: 	float b = 2.0 * dot(ray.dir, ray.origin);
nuclear@0: 	float c = dot(ray.origin, ray.origin) - rad * rad;
nuclear@0: 
nuclear@0: 	float d = b * b - 4.0 * a * c;
nuclear@0: 	if(d < 0.0) return res;
nuclear@0: 
nuclear@0: 	float sqrt_d = sqrt(d);
nuclear@0: 	float t1 = (-b + sqrt_d) / (2.0 * a);
nuclear@0: 	float t2 = (-b - sqrt_d) / (2.0 * a);
nuclear@0: 
nuclear@0: 	if((t1 >= 0.0 || t2 >= 0.0)) {
nuclear@0: 		if(t1 < 0.0) t1 = t2;
nuclear@0: 		if(t2 < 0.0) t2 = t1;
nuclear@0: 		
nuclear@0: 		res.hit = true;
nuclear@0: 		res.t = min(t1, t2);
nuclear@0: 		res.pos = ray.origin + ray.dir * res.t;
nuclear@0: 		res.color = vec3(1.0, 0.3, 0.2);
nuclear@0: 		res.normal = res.pos / rad;
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	return res;
nuclear@0: }
nuclear@0: 
nuclear@0: #define FLOOR_HEIGHT	(-2.0)
nuclear@0: 
nuclear@0: ISect ray_floor(Ray ray)
nuclear@0: {
nuclear@0: 	ISect res;
nuclear@0: 	res.hit = false;
nuclear@0: 
nuclear@0: 	if(ray.origin.y < FLOOR_HEIGHT || ray.dir.y >= 0.0) {
nuclear@0: 		return res;
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	res.normal = vec3(0.0, 1.0, 0.0);
nuclear@0: 	float ndotdir = dot(res.normal, ray.dir);
nuclear@0: 
nuclear@0: 	float t = (FLOOR_HEIGHT - ray.origin.y) / ndotdir;
nuclear@0: 	res.pos = ray.origin + ray.dir * t;
nuclear@0: 
nuclear@0: 	if(abs(res.pos.x) > 8.0 || abs(res.pos.z) > 8.0) {
nuclear@0: 		res.hit = false;
nuclear@0: 	} else {
nuclear@0: 		res.hit = true;
nuclear@0: 	
nuclear@0: 		float chess = mod(floor(res.pos.x) + floor(res.pos.z), 2.0);
nuclear@0: 		res.color = mix(vec3(0.498, 0.165, 0.149), vec3(0.776, 0.851, 0.847), chess);
nuclear@0: 		res.kr = 0.0;
nuclear@0: 	}
nuclear@0: 	return res;
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@0: