/*
* path trace across whole screen image.
*/
void
ri_transport_pathtrace(const ri_display_drv_t *ddrv)
{
int i;
int x, y;
int nsamples; /* nsamples per pixel */
int ntotalpixels;
int nfinishedpixels;
double dcol[3]; /* tempolary color buffer */
float fcol[3];
ri_option_t *opt; /* rendering options */
ri_vector_t radiance;
/* Initialize */
opt = ri_render_get()->context->option;
pixwidth = opt->camera->horizontal_resolution;
pixheight = opt->camera->vertical_resolution;
nsamples = opt->pt_nsamples;
ntotalpixels = pixwidth * pixheight * nsamples;
nfinishedpixels = 0;
light = (ri_light_t *)(ri_list_first(ri_render_get()->lightlist)->data);
get_camera(&cam_pos, &cam_dir, &c2w);
/* for each pixel, trace nsamples rays. */
for (x = 0; x < pixwidth; x++) {
for (y = pixheight - 1; y >= 0; y--) {
dcol[0] = 0.0; dcol[1] = 0.0; dcol[2] = 0.0;
for (i = 0; i < nsamples; i++) {
trace_pixel(&radiance, x, y);
// add_color(x, y, radiance);
dcol[0] += (double)radiance.f[0];
dcol[1] += (double)radiance.f[1];
dcol[2] += (double)radiance.f[2];
}
nfinishedpixels += nsamples;
#if 0
printf("%f %% finished\r",
(float)(nfinishedpixels * 100.0 /
ntotalpixels));
fflush(stdout);
#endif
fcol[0] = (float)(dcol[0] / (double)nsamples);
fcol[1] = (float)(dcol[1] / (double)nsamples);
fcol[2] = (float)(dcol[2] / (double)nsamples);
ddrv->write(x, pixheight - 1 - y, &fcol[0]);
}
}
}
/**
* Raytraces some portion of the scene. Should raytrace for about
* max_time duration and then return, even if the raytrace is not copmlete.
* The results should be placed in the given buffer.
* @param buffer The buffer into which to place the color data. It is
* 32-bit RGBA (4 bytes per pixel), in row-major order.
* @param max_time, If non-null, the maximum suggested time this
* function raytrace before returning, in seconds. If null, the raytrace
* should run to completion.
* @return true if the raytrace is complete, false if there is more
* work to be done.
*/
bool Raytracer::raytrace( unsigned char *buffer, real_t* max_time )
{
// TODO Add any modifications to this algorithm, if needed.
static long start_time; // used to show how long time ray tracing cost
if (0 == current_row)
start_time = clock();
static const size_t PRINT_INTERVAL = 64;
// the time in milliseconds that we should stop
unsigned int end_time = 0;
bool is_done = false;
if ( max_time ) {
// convert duration to milliseconds
unsigned int duration = (unsigned int) ( *max_time * 1000 );
end_time = SDL_GetTicks() + duration;
}
// until time is up, run the raytrace. we render an entire row at once
// for simplicity and efficiency.
for ( ; !max_time || end_time > SDL_GetTicks(); ++current_row ) {
if ( current_row % PRINT_INTERVAL == 0 ) {
printf( "Raytracing (row %u)...\n", current_row );
}
// we're done if we finish the last row
is_done = current_row == height;
// break if we finish
if ( is_done )
break;
for ( size_t x = 0; x < width; ++x ) {
// trace a pixel
Color3 color = trace_pixel( scene, x, current_row, width, height );
// write the result to the buffer, always use 1.0 as the alpha
color.to_array( &buffer[4 * ( current_row * width + x )] );
}
}
if ( is_done ) {
printf( "Done raytracing!\n" );
printf( "Used %d milliseconds.\n", clock()-start_time );
}
return is_done;
}
// Raytraces some portion of the scene
bool Raytracer::raytrace( unsigned char *buffer, real_t* max_time )
{
static const size_t PRINT_INTERVAL = 64;
unsigned int end_time = 0;
bool is_done;
if ( max_time ) {
// convert duration to milliseconds
unsigned int duration = (unsigned int) ( *max_time * 1000 );
end_time = SDL_GetTicks() + duration;
}
// until time is up, run the raytrace. we render an entire row at once
for ( ; !max_time || end_time > SDL_GetTicks(); ++current_row ) {
if ( current_row % PRINT_INTERVAL == 0 ) {
printf( "Raytracing (row %u)...\n", current_row );
}
// we're done if we finish the last row
is_done = current_row == height;
if ( is_done )
break;
for ( size_t x = 0; x < width; ++x ) {
// trace a pixel
Color3 color = trace_pixel( scene, x, current_row, width, height );
color.to_array( &buffer[4 * ( current_row * width + x )] );
}
}
if ( is_done ) {
printf( "Done raytracing!\n" );
}
return is_done;
}
/**
* Performs a raytrace on the given pixel on the current scene.
* The pixel is relative to the bottom-left corner of the image.
*/
Color3 Raytracer::trace_pixel(int recursions, const Ray& ray, float refractive)
{
size_t num_geometries = scene->num_geometries();
bool hit_any = false; // if any geometries were hit
IsectInfo min_info; // everything we're calculating from intersection
Vector3 intersection_point = Vector3::Zero;
// run intersection test on every object in scene
for (size_t i = 0; i < num_geometries; i++)
{
IsectInfo info;
// intersect returns true if there's a hit, false if not, and sets
// values in info struct
bool hit = scene->get_geometries()[i]->intersect_ray(ray, info);
if (hit && info.time < min_info.time) // min_info.time initializes to inf
{
min_info = info;
intersection_point = ray.eye + (min_info.time * ray.dir);
hit_any = true;
}
}
// found a hit
if (hit_any)
{
Color3 direct;
Color3 diffuse = Color3::Black;
Color3 ambient = scene->ambient_light * min_info.ambient;
float angle = dot(ray.dir, min_info.normal);
// compute reflected ray
Ray incident_ray;
incident_ray.dir = ray.dir - 2 * angle * min_info.normal;
incident_ray.dir = normalize(incident_ray.dir);
incident_ray.eye = intersection_point + eps * incident_ray.dir;
// no-refraction case
if (min_info.refractive == 0.0)
{
diffuse = get_diffuse(incident_ray.eye, min_info.normal,
min_info.diffuse, eps);
direct = min_info.texture * (ambient + diffuse);
// return direct light and reflected light if we have recursions left
if (recursions >= max_recursion_depth)
{
return direct;
}
return direct + min_info.texture * min_info.specular *
trace_pixel(recursions + 1, incident_ray, refractive);
}
// refraction case
else
{
// return black if no more recursions
if (recursions >= max_recursion_depth)
{
return Color3::Black;
}
float c;
Ray transmitted_ray;
float refract_ratio = refractive / min_info.refractive;
// negative dot product between ray and normal indicates entering object
if (angle < 0.0)
{
refract(ray.dir, min_info.normal, refract_ratio, &transmitted_ray.dir);
c = dot(-1.0 * ray.dir, min_info.normal);
}
else
{
// exiting object
if (refract(ray.dir, (-1.0 * min_info.normal), min_info.refractive,
&transmitted_ray.dir))
{
c = dot(transmitted_ray.dir, min_info.normal);
}
// total internal reflection
else
{
return trace_pixel(recursions + 1, incident_ray, refractive);
}
}
// schlick approximation to fresnel equations
float R_0 = pow(refract_ratio - 1, 2) / pow(refract_ratio + 1, 2);
float R = R_0 + (1 - R_0) * pow(1 - c, 5);
transmitted_ray.eye = intersection_point + eps * transmitted_ray.dir;
// return reflected and refracted rays
return R * trace_pixel(recursions + 1, incident_ray, refractive) +
(1.0 - R) * trace_pixel(recursions + 1, transmitted_ray,
min_info.refractive);
}
}
// didn't hit anything - return background color
else
{
return scene->background_color;
}
}
Color3 Raytracer::trace_pixel_end(int recursions, const Ray& ray, float refractive,
IsectInfo min_info)
{
Color3 direct;
Color3 diffuse = Color3::Black;
Color3 ambient = scene->ambient_light * min_info.ambient;
float angle = dot(ray.dir, min_info.normal);
// compute reflected ray
Vector3 intersection_point = ray.eye + (min_info.time * ray.dir);
Ray incident_ray;
incident_ray.dir = ray.dir - 2 * angle * min_info.normal;
incident_ray.dir = normalize(incident_ray.dir);
incident_ray.eye = intersection_point + eps * incident_ray.dir;
// no-refraction case
if (min_info.refractive == 0.0)
{
diffuse = get_diffuse(incident_ray.eye, min_info.normal,
min_info.diffuse, eps);
direct = min_info.texture * (ambient + diffuse);
// return direct light and reflected light if we have recursions left
if (recursions >= max_recursion_depth)
{
return direct;
}
return direct + min_info.texture * min_info.specular *
trace_pixel(recursions + 1, incident_ray, refractive);
}
// refraction case
else
{
// return black if no more recursions
if (recursions >= max_recursion_depth)
{
return Color3::Black;
}
float c;
Ray transmitted_ray;
float refract_ratio = refractive / min_info.refractive;
// negative dot product between ray and normal indicates entering object
if (angle < 0.0)
{
refract(ray.dir, min_info.normal, refract_ratio, &transmitted_ray.dir);
c = dot(-1.0 * ray.dir, min_info.normal);
}
else
{
// exiting object
if (refract(ray.dir, (-1.0 * min_info.normal), min_info.refractive,
&transmitted_ray.dir))
{
c = dot(transmitted_ray.dir, min_info.normal);
}
// total internal reflection
else
{
return trace_pixel(recursions + 1, incident_ray, refractive);
}
}
// schlick approximation to fresnel equations
float R_0 = pow(refract_ratio - 1, 2) / pow(refract_ratio + 1, 2);
float R = R_0 + (1 - R_0) * pow(1 - c, 5);
transmitted_ray.eye = intersection_point + eps * transmitted_ray.dir;
// return reflected and refracted rays
return R * trace_pixel(recursions + 1, incident_ray, refractive) +
(1.0 - R) * trace_pixel(recursions + 1, transmitted_ray,
min_info.refractive);
}
}