1 files changed, 188 insertions, 0 deletions
diff --git a/src/modules/ray/ray_scene.c b/src/modules/ray/ray_scene.c
new file mode 100644
index 0000000..e44990b
--- /dev/null
+++ b/src/modules/ray/ray_scene.c
@@ -0,0 +1,188 @@
+#include <stdlib.h>
+#include <math.h>
+
+#include "fb.h"
+
+#include "ray_camera.h"
+#include "ray_color.h"
+#include "ray_object.h"
+#include "ray_ray.h"
+#include "ray_scene.h"
+#include "ray_threads.h"
+
+#define MAX_RECURSION_DEPTH	5
+
+
+static ray_color_t trace_ray(ray_scene_t *scene, ray_ray_t *ray, unsigned depth);
+
+
+/* Determine if the ray is obstructed by an object within the supplied distance, for shadows */
+static inline int ray_is_obstructed(ray_scene_t *scene, ray_ray_t *ray, float distance)
+{
+	unsigned	i;
+
+	for (i = 0; i < scene->n_objects; i++) {
+		float	ood;
+
+		if (scene->objects[i].type == RAY_OBJECT_TYPE_LIGHT)
+			continue;
+
+		if (ray_object_intersects_ray(&scene->objects[i], ray, &ood) &&
+		    ood < distance) {
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+
+/* Determine the color @ distance on ray on object viewed from origin */
+static inline ray_color_t shade_ray(ray_scene_t *scene, ray_ray_t *ray, ray_object_t *object, float distance, unsigned depth)
+{
+	ray_surface_t	surface;
+	ray_color_t	color;
+	ray_3f_t	rvec = ray_3f_mult_scalar(&ray->direction, distance);
+	ray_3f_t	intersection = ray_3f_sub(&ray->origin, &rvec);
+	ray_3f_t	normal = ray_object_normal(object, &intersection);
+	unsigned	i;
+
+	surface = ray_object_surface(object, &intersection);
+	color = ray_3f_mult_scalar(&scene->ambient_color, scene->ambient_brightness);
+	color = ray_3f_mult(&surface.color, &color);
+
+	/* visit lights for shadows and illumination */
+	for (i = 0; i < scene->n_lights; i++) {
+		ray_3f_t	lvec = ray_3f_sub(&scene->lights[i].light.emitter.point.center, &intersection);
+		float		ldist = ray_3f_length(&lvec);
+		float		lvec_normal_dot;
+		ray_ray_t	shadow_ray;
+
+		lvec = ray_3f_mult_scalar(&lvec, (1.0f / ldist)); /* normalize lvec */
+#if 1
+		/* skip this light if it's obstructed,
+		 * we must shift the origin slightly towards the light to prevent
+		 * spurious self-obstruction at the ray:object intersection */
+		/* negate the light vector so it's pointed at the light rather than from it */
+		shadow_ray.direction = ray_3f_negate(&lvec);
+		shadow_ray.origin = ray_3f_mult_scalar(&shadow_ray.direction, 0.00001f);
+		shadow_ray.origin = ray_3f_add(&shadow_ray.origin, &intersection);
+
+		if (ray_is_obstructed(scene, &shadow_ray, ldist))
+			continue;
+#endif
+		lvec_normal_dot = ray_3f_dot(&normal, &lvec);
+
+		if (lvec_normal_dot > 0) {
+#if 1
+			float		rvec_lvec_dot = ray_3f_dot(&ray->direction, &lvec);
+			ray_color_t	diffuse;
+			ray_color_t	specular;
+
+			diffuse = ray_3f_mult_scalar(&surface.color, lvec_normal_dot);
+			diffuse = ray_3f_mult_scalar(&diffuse, surface.diffuse);
+			color = ray_3f_add(&color, &diffuse);
+
+			/* FIXME: assumes light is a point for its color, and 20 is a constant "Phong exponent",
+			 * which should really be object/surface-specific
+			 */
+			specular = ray_3f_mult_scalar(&scene->lights[i].light.emitter.point.surface.color, powf(rvec_lvec_dot, 20));
+			specular = ray_3f_mult_scalar(&specular, surface.specular);
+			color = ray_3f_add(&color, &specular);
+#else
+			ray_color_t	diffuse;
+
+			diffuse = ray_3f_mult_scalar(&surface.color, lvec_normal_dot);
+			color = ray_3f_add(&color, &diffuse);
+#endif
+		}
+	}
+
+	/* generate a reflection ray */
+#if 1
+	float		dot = ray_3f_dot(&ray->direction, &normal);
+	ray_ray_t	reflected_ray = { .direction = ray_3f_mult_scalar(&normal, dot * 2.0f) };
+	ray_3f_t	reflection;
+
+	reflected_ray.origin = intersection;
+	reflected_ray.direction = ray_3f_sub(&ray->direction, &reflected_ray.direction);
+
+	reflection = trace_ray(scene, &reflected_ray, depth + 1);
+	reflection = ray_3f_mult_scalar(&reflection, surface.specular);
+	color = ray_3f_add(&color, &reflection);
+#endif
+
+	/* TODO: generate a refraction ray */
+
+	return color;
+}
+
+
+static ray_color_t trace_ray(ray_scene_t *scene, ray_ray_t *ray, unsigned depth)
+{
+	ray_object_t	*nearest_object = NULL;
+	float		nearest_object_distance = INFINITY;
+	ray_color_t	color = { .x = 0.0, .y = 0.0, .z = 0.0 };
+	unsigned	i;
+
+	depth++;
+	if (depth > MAX_RECURSION_DEPTH)
+		return color;
+
+	for (i = 0; i < scene->n_objects; i++) {
+		float	distance;
+
+		/* Does this ray intersect object? */
+		if (ray_object_intersects_ray(&scene->objects[i], ray, &distance)) {
+
+			/* Is it the nearest intersection? */
+			if (!nearest_object ||
+			    distance < nearest_object_distance) {
+				nearest_object = &scene->objects[i];
+				nearest_object_distance = distance;
+			}
+		}
+	}
+
+	if (nearest_object)
+		color = shade_ray(scene, ray, nearest_object, nearest_object_distance, depth);
+
+	depth--;
+
+	return color;
+}
+
+
+void ray_scene_render_fragment(ray_scene_t *scene, ray_camera_t *camera, fb_fragment_t *fragment)
+{
+	ray_camera_frame_t	frame;
+	ray_ray_t		ray;
+	uint32_t		*buf = fragment->buf;
+	unsigned		stride = fragment->stride / 4;
+
+	ray_camera_frame_begin(camera, fragment, &ray, &frame);
+	do {
+		do {
+			*buf = ray_color_to_uint32_rgb(trace_ray(scene, &ray, 0));
+			buf++;
+		} while (ray_camera_frame_x_step(&frame));
+
+		buf += stride;
+	} while (ray_camera_frame_y_step(&frame));
+}
+
+/* we expect fragments[threads->n_threads + 1], or fragments[1] when threads == NULL */
+void ray_scene_render_fragments(ray_scene_t *scene, ray_camera_t *camera, ray_threads_t *threads, fb_fragment_t *fragments)
+{
+	unsigned	n_threads = threads ? threads->n_threads + 1 : 1;
+	unsigned	i;
+
+	for (i = 1; i < n_threads; i++)
+		ray_thread_fragment_submit(&threads->threads[i - 1], scene, camera, &fragments[i]);
+
+	/* always render the zero fragment in-line */
+	ray_scene_render_fragment(scene, camera, &fragments[0]);
+
+	for (i = 1; i < n_threads; i++)
+		ray_thread_wait_idle(&threads->threads[i - 1]);
+}