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Diffstat (limited to 'libdimension/ray_trace.c')
| -rw-r--r-- | libdimension/ray_trace.c | 503 |
1 files changed, 503 insertions, 0 deletions
diff --git a/libdimension/ray_trace.c b/libdimension/ray_trace.c new file mode 100644 index 0000000..dd84a26 --- /dev/null +++ b/libdimension/ray_trace.c @@ -0,0 +1,503 @@ +/************************************************************************* + * Copyright (C) 2010-2011 Tavian Barnes <tavianator@tavianator.com> * + * * + * This file is part of The Dimension Library. * + * * + * The Dimension Library is free software; you can redistribute it and/ * + * or modify it under the terms of the GNU Lesser General Public License * + * as published by the Free Software Foundation; either version 3 of the * + * License, or (at your option) any later version. * + * * + * The Dimension Library is distributed in the hope that it will be * + * useful, but WITHOUT ANY WARRANTY; without even the implied warranty * + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * + * Lesser General Public License for more details. * + * * + * You should have received a copy of the GNU Lesser General Public * + * License along with this program. If not, see * + * <http://www.gnu.org/licenses/>. * + *************************************************************************/ + +/** + * @file + * The ray-tracing algorithm. + */ + +#include "dimension-internal.h" +#include <stdlib.h> + +/* + * Boilerplate for multithreading + */ + +/** Payload type for passing arguments to worker threads. */ +typedef struct { + dmnsn_future *future; + dmnsn_scene *scene; + dmnsn_prtree *prtree; +} dmnsn_ray_trace_payload; + +/* Ray-trace a scene */ +void +dmnsn_ray_trace(dmnsn_scene *scene) +{ + dmnsn_future *future = dmnsn_ray_trace_async(scene); + if (dmnsn_future_join(future) != 0) { + dmnsn_error("Error occured while ray-tracing."); + } +} + +/** Background thread callback. */ +static int dmnsn_ray_trace_scene_thread(void *ptr); + +/* Ray-trace a scene in the background */ +dmnsn_future * +dmnsn_ray_trace_async(dmnsn_scene *scene) +{ + dmnsn_future *future = dmnsn_new_future(); + + dmnsn_ray_trace_payload *payload = + dmnsn_malloc(sizeof(dmnsn_ray_trace_payload)); + payload->future = future; + payload->scene = scene; + + dmnsn_new_thread(future, dmnsn_ray_trace_scene_thread, payload); + + return future; +} + +/** Worker thread callback. */ +static int dmnsn_ray_trace_scene_concurrent(void *ptr, unsigned int thread, + unsigned int nthreads); + +/* Thread callback -- set up the multithreaded engine */ +static int +dmnsn_ray_trace_scene_thread(void *ptr) +{ + dmnsn_ray_trace_payload *payload = ptr; + + /* Pre-calculate bounding box transformations, etc. */ + dmnsn_scene_initialize(payload->scene); + + /* Time the bounding tree construction */ + dmnsn_timer_start(&payload->scene->bounding_timer); + payload->prtree = dmnsn_new_prtree(payload->scene->objects); + dmnsn_timer_stop(&payload->scene->bounding_timer); + + /* Set up the future object */ + dmnsn_future_set_total(payload->future, payload->scene->canvas->height); + + /* Time the render itself */ + dmnsn_timer_start(&payload->scene->render_timer); + int ret = dmnsn_execute_concurrently(dmnsn_ray_trace_scene_concurrent, + payload, payload->scene->nthreads); + dmnsn_timer_stop(&payload->scene->render_timer); + + dmnsn_delete_prtree(payload->prtree); + dmnsn_free(payload); + + return ret; +} + +/* + * Ray-tracing algorithm + */ + +/** The current state of the ray-tracing engine. */ +typedef struct dmnsn_rtstate { + const struct dmnsn_rtstate *parent; + + const dmnsn_scene *scene; + const dmnsn_intersection *intersection; + const dmnsn_texture *texture; + const dmnsn_interior *interior; + const dmnsn_prtree *prtree; + unsigned int reclevel; + + dmnsn_vector r; + dmnsn_vector pigment_r; + dmnsn_vector viewer; + dmnsn_vector reflected; + dmnsn_vector light; + + dmnsn_color pigment; + dmnsn_color diffuse; + dmnsn_color additional; + + double ior; + + dmnsn_color adc_value; +} dmnsn_rtstate; + +/** Compute a ray-tracing state from an intersection. */ +static inline void +dmnsn_rtstate_initialize(dmnsn_rtstate *state, + const dmnsn_intersection *intersection) +{ + state->intersection = intersection; + state->texture = intersection->object->texture; + state->interior = intersection->object->interior; + + state->r = dmnsn_line_point(intersection->ray, intersection->t); + state->pigment_r = dmnsn_transform_point( + intersection->object->pigment_trans, + state->r + ); + state->viewer = dmnsn_vector_normalized( + dmnsn_vector_negate(intersection->ray.n) + ); + state->reflected = dmnsn_vector_sub( + dmnsn_vector_mul( + 2*dmnsn_vector_dot(state->viewer, intersection->normal), + intersection->normal), + state->viewer + ); + + state->pigment = dmnsn_black; + state->diffuse = dmnsn_black; + state->additional = dmnsn_black; +} + +/** Main helper for dmnsn_ray_trace_scene_impl - shoot a ray. */ +static dmnsn_color dmnsn_ray_shoot(dmnsn_rtstate *state, dmnsn_line ray); + +/* Actually ray-trace a scene */ +static int +dmnsn_ray_trace_scene_concurrent(void *ptr, unsigned int thread, + unsigned int nthreads) +{ + const dmnsn_ray_trace_payload *payload = ptr; + dmnsn_future *future = payload->future; + dmnsn_scene *scene = payload->scene; + dmnsn_prtree *prtree = payload->prtree; + + dmnsn_rtstate state = { + .parent = NULL, + .scene = scene, + .prtree = prtree, + }; + + /* Iterate through each pixel */ + for (size_t y = thread; y < scene->canvas->height; y += nthreads) { + for (size_t x = 0; x < scene->canvas->width; ++x) { + /* Get the ray corresponding to the (x,y)'th pixel */ + dmnsn_line ray = dmnsn_camera_ray( + scene->camera, + ((double)(x + scene->region_x))/(scene->outer_width - 1), + ((double)(y + scene->region_y))/(scene->outer_height - 1) + ); + + /* Shoot a ray */ + state.reclevel = scene->reclimit; + state.ior = 1.0; + state.adc_value = dmnsn_white; + dmnsn_color color = dmnsn_ray_shoot(&state, ray); + + dmnsn_canvas_set_pixel(scene->canvas, x, y, color); + } + + dmnsn_future_increment(future); + } + + return 0; +} + +/** Calculate the background color. */ +static dmnsn_color +dmnsn_trace_background(const dmnsn_rtstate *state, dmnsn_line ray) +{ + dmnsn_pigment *background = state->scene->background; + if (state->scene->quality & DMNSN_RENDER_PIGMENT) { + return dmnsn_pigment_evaluate(background, dmnsn_vector_normalized(ray.n)); + } else { + return background->quick_color; + } +} + +/** Calculate the base pigment at the intersection. */ +static void +dmnsn_trace_pigment(dmnsn_rtstate *state) +{ + dmnsn_pigment *pigment = state->texture->pigment; + if (state->scene->quality & DMNSN_RENDER_PIGMENT) { + state->pigment = dmnsn_pigment_evaluate(pigment, state->pigment_r); + } else { + state->pigment = pigment->quick_color; + } + + state->diffuse = state->pigment; +} + +/** Get the color of a light ray at an intersection point. */ +static bool +dmnsn_trace_light_ray(dmnsn_rtstate *state, const dmnsn_light *light, + dmnsn_color *color) +{ + /** @todo: Start at the light source */ + dmnsn_line shadow_ray = dmnsn_new_line( + state->r, + light->direction_fn(light, state->r) + ); + state->light = dmnsn_vector_normalized(shadow_ray.n); + /* Add epsilon to avoid hitting ourselves with the shadow ray */ + shadow_ray = dmnsn_line_add_epsilon(shadow_ray); + + /* Check if we're casting a shadow on ourself */ + if (dmnsn_vector_dot(shadow_ray.n, state->intersection->normal) + * dmnsn_vector_dot(state->viewer, state->intersection->normal) < 0.0) + { + return false; + } + + *color = light->illumination_fn(light, state->r); + + /* Test for shadow ray intersections */ + unsigned int reclevel = state->reclevel; + while (reclevel-- > 0 + && dmnsn_color_intensity(*color) >= state->scene->adc_bailout) + { + dmnsn_intersection shadow_caster; + bool shadow_was_cast = dmnsn_prtree_intersection(state->prtree, shadow_ray, + &shadow_caster, false); + + if (!shadow_was_cast || !light->shadow_fn(light, shadow_caster.t)) { + return true; + } + + /* Handle transparency */ + if (state->scene->quality & DMNSN_RENDER_TRANSPARENCY) { + dmnsn_rtstate shadow_state = *state; + dmnsn_rtstate_initialize(&shadow_state, &shadow_caster); + dmnsn_trace_pigment(&shadow_state); + + if (shadow_state.pigment.trans >= dmnsn_epsilon) { + /* Reflect the light */ + const dmnsn_reflection *reflection = + shadow_state.texture->finish.reflection; + if ((state->scene->quality & DMNSN_RENDER_REFLECTION) && reflection) { + dmnsn_color reflected = reflection->reflection_fn( + reflection, *color, shadow_state.pigment, shadow_state.reflected, + shadow_state.intersection->normal + ); + *color = dmnsn_color_sub(*color, reflected); + } + + /* Filter the light */ + *color = dmnsn_filter_light(*color, shadow_state.pigment); + shadow_ray.x0 = dmnsn_line_point(shadow_ray, shadow_caster.t); + shadow_ray.n = light->direction_fn(light, shadow_ray.x0); + shadow_ray = dmnsn_line_add_epsilon(shadow_ray); + continue; + } + } + + break; + } + + return false; +} + +/** Handle light, shadow, and shading. */ +static void +dmnsn_trace_lighting(dmnsn_rtstate *state) +{ + /* The ambient color */ + state->diffuse = dmnsn_black; + + const dmnsn_finish *finish = &state->texture->finish; + if (finish->ambient) { + state->diffuse = + finish->ambient->ambient_fn(finish->ambient, state->pigment); + } + + /* Iterate over each light */ + DMNSN_ARRAY_FOREACH (dmnsn_light **, light, state->scene->lights) { + dmnsn_color light_color; + if (dmnsn_trace_light_ray(state, *light, &light_color)) { + if (state->scene->quality & DMNSN_RENDER_FINISH) { + /* Get this light's specular contribution to the object */ + dmnsn_color specular = dmnsn_black; + if (finish->specular) { + specular = finish->specular->specular_fn( + finish->specular, light_color, state->pigment, state->light, + state->intersection->normal, state->viewer + ); + light_color = dmnsn_color_sub(light_color, specular); + } + + /* Reflect the light */ + const dmnsn_reflection *reflection = state->texture->finish.reflection; + if ((state->scene->quality & DMNSN_RENDER_REFLECTION) && reflection) { + dmnsn_color reflected = reflection->reflection_fn( + reflection, light_color, state->pigment, state->reflected, + state->intersection->normal + ); + light_color = dmnsn_color_sub(light_color, reflected); + } + + /* Get this light's diffuse contribution to the object */ + dmnsn_color diffuse = dmnsn_black; + if (finish->diffuse) { + diffuse = finish->diffuse->diffuse_fn( + finish->diffuse, light_color, state->pigment, state->light, + state->intersection->normal + ); + } + + state->diffuse = dmnsn_color_add(diffuse, state->diffuse); + state->additional = dmnsn_color_add(specular, state->additional); + } else { + state->diffuse = state->pigment; + state->diffuse.trans = 0.0; + state->diffuse.filter = 0.0; + } + } + } +} + +/** Trace a reflected ray. */ +static dmnsn_color +dmnsn_trace_reflection(const dmnsn_rtstate *state) +{ + dmnsn_color reflected = dmnsn_black; + + const dmnsn_reflection *reflection = state->texture->finish.reflection; + if (reflection) { + dmnsn_line refl_ray = dmnsn_new_line(state->r, state->reflected); + refl_ray = dmnsn_line_add_epsilon(refl_ray); + + dmnsn_rtstate recursive_state = *state; + + /* Calculate ADC value */ + recursive_state.adc_value = reflection->reflection_fn( + reflection, state->adc_value, state->pigment, state->reflected, + state->intersection->normal + ); + + /* Shoot the reflected ray */ + dmnsn_color rec = dmnsn_ray_shoot(&recursive_state, refl_ray); + reflected = reflection->reflection_fn( + reflection, rec, state->pigment, state->reflected, + state->intersection->normal + ); + reflected.trans = 0.0; + reflected.filter = 0.0; + } + + return reflected; +} + +/** Handle transparency - must be called last to work correctly. */ +static void +dmnsn_trace_transparency(dmnsn_rtstate *state) +{ + if (state->pigment.trans >= dmnsn_epsilon) { + dmnsn_line trans_ray = dmnsn_new_line(state->r, state->intersection->ray.n); + trans_ray = dmnsn_line_add_epsilon(trans_ray); + + dmnsn_vector r = dmnsn_vector_normalized(trans_ray.n); + dmnsn_vector n = state->intersection->normal; + + dmnsn_rtstate recursive_state = *state; + + /* Calculate new refractive index */ + if (dmnsn_vector_dot(r, n) < 0.0) { + /* We are entering an object */ + recursive_state.ior = state->interior->ior; + recursive_state.parent = state; + } else { + /* We are leaving an object */ + recursive_state.ior = state->parent ? state->parent->ior : 1.0; + recursive_state.parent = state->parent ? state->parent->parent : NULL; + } + + /* Calculate transmitted ray direction */ + double iorr = state->ior/recursive_state.ior; /* ior ratio */ + double c1 = -dmnsn_vector_dot(r, n); + double c2 = 1.0 - iorr*iorr*(1.0 - c1*c1); + if (c2 <= 0.0) { + /* Total internal reflection */ + return; + } + c2 = sqrt(c2); + if (c1 >= 0.0) { + trans_ray.n = dmnsn_vector_add( + dmnsn_vector_mul(iorr, r), + dmnsn_vector_mul(iorr*c1 - c2, n) + ); + } else { + trans_ray.n = dmnsn_vector_add( + dmnsn_vector_mul(iorr, r), + dmnsn_vector_mul(iorr*c1 + c2, n) + ); + } + + /* Calculate ADC value */ + recursive_state.adc_value = + dmnsn_filter_light(state->adc_value, state->pigment); + + /* Shoot the transmitted ray */ + dmnsn_color rec = dmnsn_ray_shoot(&recursive_state, trans_ray); + dmnsn_color filtered = dmnsn_filter_light(rec, state->pigment); + + /* Conserve energy */ + const dmnsn_reflection *reflection = state->texture->finish.reflection; + if ((state->scene->quality & DMNSN_RENDER_REFLECTION) && reflection) { + dmnsn_color reflected = reflection->reflection_fn( + reflection, filtered, state->pigment, state->reflected, + state->intersection->normal + ); + filtered = dmnsn_color_sub(filtered, reflected); + } + + state->diffuse.filter = state->pigment.filter; + state->diffuse.trans = state->pigment.trans; + state->diffuse = dmnsn_apply_transparency(filtered, state->diffuse); + } +} + +/* Shoot a ray, and calculate the color */ +static dmnsn_color +dmnsn_ray_shoot(dmnsn_rtstate *state, dmnsn_line ray) +{ + if (state->reclevel == 0 + || dmnsn_color_intensity(state->adc_value) < state->scene->adc_bailout) + { + return dmnsn_black; + } + + --state->reclevel; + + dmnsn_intersection intersection; + bool reset = state->reclevel == state->scene->reclimit - 1; + if (dmnsn_prtree_intersection(state->prtree, ray, &intersection, reset)) { + /* Found an intersection */ + dmnsn_rtstate_initialize(state, &intersection); + + /* Pigment */ + dmnsn_trace_pigment(state); + + /* Finishes and shadows */ + if (state->scene->quality & DMNSN_RENDER_LIGHTS) { + dmnsn_trace_lighting(state); + } + + /* Reflection */ + if (state->scene->quality & DMNSN_RENDER_REFLECTION) { + state->additional = dmnsn_color_add( + dmnsn_trace_reflection(state), + state->additional + ); + } + + /* Transparency */ + if (state->scene->quality & DMNSN_RENDER_TRANSPARENCY) { + dmnsn_trace_transparency(state); + } + + return dmnsn_color_add(state->diffuse, state->additional); + } else { + /* No intersection, return the background color */ + return dmnsn_trace_background(state, ray); + } +} |