/*

 * raytracer.cc: Raytracer class

 *

 * This file is part of Pyrit Ray Tracer.

 *

 * Copyright 2006, 2007, 2008  Radek Brich

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include <pthread.h>

#include <stdio.h>

#include <stdlib.h>

#include <assert.h>

#include "raytracer.h"

int pyrit_verbosity = 2;

// Hammersley spherical point distribution

// http://www.cse.cuhk.edu.hk/~ttwong/papers/udpoint/udpoints.html

Vector Raytracer::SphereDistribute(int i, int n, Float extent, const Vector &normal)

{

	Float p, t, st, phi, phirad;

	int kk;

	t = 0;

	for (p=0.5, kk=i; kk; p*=0.5, kk>>=1)

	if (kk & 1)

		t += p;

	t = 1.0 + (t - 1.0)*extent;

	phi = (i + 0.5) / n;

	phirad =  phi * 2.0 * M_PI;

	st = sqrt(1.0 - t*t);

	Float x, y, z, xx, yy, zz, q;

	x = st * cos(phirad);

	y = st * sin(phirad);

	z = t;

	// rotate against Y axis

	q = acos(normal.z);

	zz = z*cos(q) - x*sin(q);

	xx = z*sin(q) + x*cos(q);

	yy = y;

	// rotate against Z axis

	q = atan2f(normal.y, normal.x);

	x = xx*cos(q) - yy*sin(q);

	y = xx*sin(q) + yy*cos(q);

	z = zz;

	return Vector(x, y, z);

}

/*

 P is point of intersection,

 N normal in this point,

 R direction of reflected ray,

 V direction to the viewer

*/

Colour Raytracer::PhongShader(const Shape *shape,

	const Vector &P, const Vector &N, const Vector &V)

{

	Colour col, acc;

	Material * const &mat = shape->material;

	if (mat->texture)

		col = mat->texture->evaluate(P);

	else

		col = mat->colour;

	// ambient

	acc = mat->ambient * col;

	vector<Light*>::iterator light;

	for (light = lights.begin(); light != lights.end(); light++)

	{

		const Vector L = normalize((*light)->pos - P); // direction vector to light

		const Float L_dot_N = dot(L, N);

		if (L_dot_N > 0)

		{

			// test if this light is occluded (sharp shadows)

			if ((*light)->cast_shadows) {

				const Ray shadow_ray = Ray(P, L);

				Float dist = FLT_MAX;

				if (top->nearest_intersection(shape, shadow_ray, dist))

					continue;

			}

			const Vector R = L - 2.0 * L_dot_N * N;

			const Float R_dot_V = dot(R, V);

			// diffuse

			acc += mat->diffuse * col * (*light)->colour * L_dot_N;

			// specular

			if (R_dot_V > 0)

				acc += mat->specular * (*light)->colour * powf(R_dot_V, mat->shininess);

		}

	}

	return acc;

}

	const VectorPacket &P, const VectorPacket &N, const VectorPacket &V)

{

	VectorPacket acc, colour;

	for (int i = 0; i < 4; i++)

		if (shapes[i] == NULL)

		{

			ambient_f[i] = 0;

			diffuse_f[i] = 0;

			specular_f[i] = 0;

			shininess_f[i] = 0;

		}

		else

		{

			Material * const &mat = shapes[i]->material;

			if (mat->texture)

				colour.setVector(i, mat->texture->evaluate(P.getVector(i)));

			else

				colour.setVector(i, mat->colour);

			ambient_f[i] = mat->ambient;

			diffuse_f[i] = mat->diffuse;

			specular_f[i] = mat->specular;

			shininess_f[i] = mat->shininess;

		}

	// ambient

	acc = colour * ambient;

	vector<Light*>::iterator light;

	for (light = lights.begin(); light != lights.end(); light++)

	{

		 // direction vector to light

		VectorPacket L = VectorPacket((*light)->pos) - P;

		L.normalize();

		// test if this light is occluded (sharp shadows)

		if ((*light)->cast_shadows)

		{

			const RayPacket shadow_rays = RayPacket(P, L);

			dists = mInf;

			top->packet_intersection(shapes, shadow_rays,

				dists_f, shadow_shapes);

		}

		// diffuse

		acc.selectiveAdd(valid,

		// specular

		acc.selectiveAdd(valid, spec);

	}

	return acc;

}

#endif

void Raytracer::lightScatter(const Ray &ray, const Shape *shape, int depth,

	const Vector &P, const Vector &normal, bool from_inside, Colour &col)

{

	if (depth < max_depth)

	{

		Colour trans_col, refl_col;

		Float trans = shape->material->transmissivity;

		Float refl = shape->material->reflectivity;

		const Float cos_i = - dot(normal, ray.dir);

		// reflection

		if (refl > 0.01)

		{

			Vector newdir = ray.dir + 2.0 * cos_i * normal;

			Ray newray = Ray(P, newdir);

			refl_col = raytrace(newray, depth + 1, shape);

		}

		// refraction

		if (trans > 0.01)

		{

			Float n, n1, n2;

			if (from_inside)

			{

				n1 = shape->material->refract_index;

				n2 = 1.0;

				n = n1;

			}

			else

			{

				n1 = 1.0;

				n2 = shape->material->refract_index;

				n = 1.0 / n2;

			}

			const Float sin2_t = n*n * (1 - cos_i*cos_i);

			if (sin2_t >= 1.0)

			{

					// totally reflected

					refl += trans;

					trans = 0;

			}

			else

			{

				const Float cos_t = sqrtf(1 - sin2_t);

				const Float Rdiv = 1.0/(n1*cos_i + n2*cos_t);

				const Float Rper = (n1*cos_i - n2*cos_t)*Rdiv;

				const Float Rpar = (n2*cos_i - n1*cos_t)*Rdiv;

				const Float R = (Rper*Rper + Rpar*Rpar)/2;

				refl += R*trans;

				trans = (1-R)*trans;

				Vector newdir = n * ray.dir + (n*cos_i - cos_t) * normal;

				Ray newray = Ray(P + 0.001*newdir, newdir);

				trans_col = raytrace(newray, depth + 1, NULL);

			}

		}

		col = (1-refl-trans)*col + refl*refl_col + trans*trans_col;

	}

	// ambient occlusion

	if (ao_samples && !from_inside)

	{

		Float miss = 0;

		for (int i = 0; i < ao_samples; i++)

		{

			Vector dir = SphereDistribute(i, ao_samples, ao_angle, normal);

			Ray ao_ray = Ray(P, dir);

			Float dist = ao_distance;

			Shape *shape_in_way = top->nearest_intersection(shape, ao_ray, dist);

			if (shape_in_way == NULL)

				miss += 1.0;

			else

				miss += dist / ao_distance;

		}

		Float ao_intensity = miss / ao_samples;

		col = col * ao_intensity;

	}

}

Colour Raytracer::raytrace(Ray &ray, int depth, const Shape *origin_shape)

{

	Float nearest_distance = Inf;

	Shape *nearest_shape = top->nearest_intersection(origin_shape, ray, nearest_distance);

	if (nearest_shape == NULL)

		return bg_colour;

	else

	{

		const Vector P = ray.o + ray.dir * nearest_distance; // point of intersection

		Vector normal = nearest_shape->normal(P);

		bool from_inside = false;

		// make shapes double sided

		if (dot(normal, ray.dir) > 0.0)

		{

			normal = - normal;

			from_inside = true;

		}

		// shading function

		Colour col = PhongShader(nearest_shape, P, normal, ray.dir);

		lightScatter(ray, nearest_shape, depth, P, normal, from_inside, col);

		return col;

	}

}

void Raytracer::raytracePacket(RayPacket &rays, Colour *results)

{

	union {

		float nearest_distances[4];

	};

	Shape *nearest_shapes[4];

	static const Shape *origin_shapes[4] = {NULL, NULL, NULL, NULL};

	m_nearest_distances = mInf;

	top->packet_intersection(origin_shapes, rays, nearest_distances, nearest_shapes);

	{

		for (int i = 0; i < 4; i++)

			results[i] = bg_colour;

		return;

	}

	const VectorPacket P = rays.o + rays.dir * m_nearest_distances; // point of intersection

	VectorPacket normal;

	for (int i = 0; i < 4; i++)

		if (nearest_shapes[i] != NULL)

			normal.setVector(i, nearest_shapes[i]->normal(P.getVector(i)));

	// make shapes double sided

	// shading function

	for (int i = 0; i < 4; i++)

		if (nearest_shapes[i] != NULL)

		{

			results[i] = pres.getVector(i);

			lightScatter(rays[i], nearest_shapes[i], 0,

				results[i]);

		}

		else

			results[i] = bg_colour;

}

#endif

void *Raytracer::raytrace_worker(void *d)

{

	static const int my_queue_size = 256;

	Raytracer *rt = (Raytracer*)d;

	Sample my_queue[my_queue_size];

	Colour my_colours[my_queue_size];

	int my_count;

	Ray ray;

	RayPacket rays;

	const bool can_use_packets = (rt->use_packets && rt->sampler->packetableSamples());

#endif

	for (;;)

	{

		pthread_mutex_lock(&rt->sample_queue_mutex);

		while (rt->sample_queue_count == 0)

		{

			if (rt->end_of_samples)

			{

				dbgmsg(4, "T thread [%d] exiting\n", pthread_self());

				pthread_mutex_unlock(&rt->sample_queue_mutex);

				pthread_exit(NULL);

			}

			pthread_cond_wait(&rt->sample_queue_cond, &rt->sample_queue_mutex);

		}

		if (rt->sample_queue_count >= my_queue_size)

			my_count = my_queue_size;

		else

			my_count = rt->sample_queue_count;

		rt->sample_queue_count -= my_count;

		// copy samples to local queue

		if (rt->sample_queue_pos + my_count >= rt->sample_queue_size)

		{

			register int c = rt->sample_queue_size - rt->sample_queue_pos;

			memcpy(my_queue, rt->sample_queue + rt->sample_queue_pos, c*sizeof(Sample));

			memcpy(my_queue + c, rt->sample_queue, (my_count - c)*sizeof(Sample));

			rt->sample_queue_pos = my_count - c;

		}

		else

		{

			memcpy(my_queue, rt->sample_queue + rt->sample_queue_pos,

				my_count*sizeof(Sample));

			rt->sample_queue_pos += my_count;

		}

		if (rt->sample_queue_count <= my_queue_size*2)

			pthread_cond_signal(&rt->worker_ready_cond);

		pthread_mutex_unlock(&rt->sample_queue_mutex);

		// do the work

		if (can_use_packets)

		{

			// packet ray tracing

			assert((my_count % 4) == 0);

			for (int i = 0; i < my_count; i+=4)

			{

				rt->camera->makeRayPacket(my_queue + i, rays);

				rt->raytracePacket(rays, my_colours + i);

			}

		}

		else

#endif

		{

			// single ray tracing

			for (int i = 0; i < my_count; i++)

			{

				ray = rt->camera->makeRay(my_queue[i]);

				my_colours[i] = rt->raytrace(ray, 0, NULL);

			}

		}

		// save the results

		pthread_mutex_lock(&rt->sampler_mutex);

		for (int i = 0; i < my_count; i++)

			rt->sampler->saveSample(my_queue[i], my_colours[i]);

		pthread_mutex_unlock(&rt->sampler_mutex);

	}

}

void Raytracer::render()

{

	if (!sampler || !camera || !top)

		return;

	static const int my_count_max = 256;

	sample_queue_size = my_count_max*2*num_threads;

	sample_queue = new Sample [sample_queue_size];

	sample_queue_count = 0;

	int my_count, my_pos;

	int sampnum = 0, sampdone;

	int phase = 1;

	bool more_samples;

	sampler->init();

	// create workers

	dbgmsg(1, "* using %d threads\n", num_threads);

	dbgmsg(1, "* raytracing...\n");

	while ( (sampnum = sampler->initSampleSet()) > 0 )

	{

		my_pos = 0;

		sample_queue_pos = 0;

		sampdone = 0;

		end_of_samples = false;

		for (int t = 0; t < num_threads; t++)

		{

			int rc = pthread_create(&threads[t], NULL, raytrace_worker, (void*)this);

			if (rc) {

				dbgmsg(0, "\nE pthread_create unsuccessful, return code was %d\n", rc);

				exit(1);

			}

		}

		dbgmsg(2, "- phase %d:  0%% done", phase);

		pthread_mutex_lock(&sampler_mutex);

		for (;;)

		{

			my_count = 0;

			while ( more_samples = sampler->nextSample(&sample_queue[my_pos++]) )

			{

				my_count++;

				if (my_pos >= sample_queue_size)

					my_pos = 0;

				if (my_count >= my_count_max)

					break;

			}