ray: split scene data from render state

This introduces ray_render_t, and ray_render.[ch].

The _prepared member of ray_scene_t has been moved to ray_render_t,
and the other _prepared members (e.g. objects) will follow.

Up until now I've just been sticking the precomputed state under
_prepared members of their associated structures, and simply using
convention to enforce anything resembling an api boundary.  It's
been convenient without being inefficient, but I'd like to move
the ray code into more of a reusable library and this wart needs
to be addressed.

The render state is also where any spatial indexes will be built
and maintained, another thing I've been experimenting with.

Note most of the churn here is just renaming ray_scene.c to
ray_render.c.  A nearly global s/ray_scene/ray_render/ has occurred,
now that ray_scene_t really only serves as glue to bind objects,
lights, and scene-global properties into a cohesive unit.

5 files changed, 79 insertions, 38 deletions

diff --git a/src/modules/ray/Makefile.am b/src/modules/ray/Makefile.am
index 872efb6..a0d7cb9 100644
--- a/src/modules/ray/Makefile.am
+++ b/src/modules/ray/Makefile.am
@@ -1,4 +1,4 @@
 noinst_LIBRARIES = libray.a
-libray_a_SOURCES = ray_3f.h ray.c ray_camera.c ray_camera.h ray_color.h ray_euler.c ray_euler.h ray_light_emitter.h ray_object.h ray_object_light.h ray_object_plane.h ray_object_point.h ray_object_sphere.h ray_object_type.h ray_ray.h ray_scene.c ray_scene.h ray_surface.h
+libray_a_SOURCES = ray_3f.h ray.c ray_camera.c ray_camera.h ray_color.h ray_euler.c ray_euler.h ray_light_emitter.h ray_object.h ray_object_light.h ray_object_plane.h ray_object_point.h ray_object_sphere.h ray_object_type.h ray_ray.h ray_render.c ray_render.h ray_scene.h ray_surface.h
 libray_a_CFLAGS = @ROTOTILLER_CFLAGS@ -ffast-math
 libray_a_CPPFLAGS = @ROTOTILLER_CFLAGS@ -I@top_srcdir@/src
diff --git a/src/modules/ray/ray.c b/src/modules/ray/ray.c
index 5f6326d..bb9c042 100644
--- a/src/modules/ray/ray.c
+++ b/src/modules/ray/ray.c
@@ -8,6 +8,7 @@
 
 #include "ray_camera.h"
 #include "ray_object.h"
+#include "ray_render.h"
 #include "ray_scene.h"
 
 /* Copyright (C) 2016-2017 Vito Caputo <vcaputo@pengaru.com> */
@@ -118,6 +119,7 @@ static float	r;
 
 
 typedef struct ray_context_t {
+	ray_render_t	*render;
 } ray_context_t;
 
 
@@ -142,6 +144,8 @@ static int ray_fragmenter(void *context, const fb_fragment_t *fragment, unsigned
 /* prepare a frame for concurrent rendering */
 static void ray_prepare_frame(void *context, unsigned n_cpus, fb_fragment_t *fragment, rototiller_fragmenter_t *res_fragmenter)
 {
+	ray_context_t	*ctxt = context;
+
 	*res_fragmenter = ray_fragmenter;
 
 	/* TODO: the camera doesn't need the width and height anymore, the fragment has the frame_width/frame_height */
@@ -169,14 +173,24 @@ static void ray_prepare_frame(void *context, unsigned n_cpus, fb_fragment_t *fra
 	/* tilt camera pitch in time with up and down movements, phase shifted appreciably */
 	camera.orientation.pitch = -(sinf((M_PI * 1.5f) + r * 1.3f) * .6f + -.35f);
 #endif
-	ray_scene_prepare(&scene, &camera);
+	ctxt->render = ray_render_new(&scene, &camera);
 }
 
 
 /* ray trace a simple scene into the fragment */
 static void ray_render_fragment(void *context, fb_fragment_t *fragment)
 {
-	ray_scene_render_fragment(&scene, fragment);
+	ray_context_t	*ctxt = context;
+
+	ray_render_trace_fragment(ctxt->render, fragment);
+}
+
+
+static void ray_finish_frame(void *context, fb_fragment_t *fragment)
+{
+	ray_context_t	*ctxt = context;
+
+	ray_render_free(ctxt->render);
 }
 
 
@@ -185,6 +199,7 @@ rototiller_module_t	ray_module = {
 	.destroy_context = ray_destroy_context,
 	.prepare_frame = ray_prepare_frame,
 	.render_fragment = ray_render_fragment,
+	.finish_frame = ray_finish_frame,
 	.name = "ray",
 	.description = "Ray tracer (threaded)",
 	.author = "Vito Caputo <vcaputo@pengaru.com>",
diff --git a/src/modules/ray/ray_scene.c b/src/modules/ray/ray_render.c
index 21a3bfa..bfa5112 100644
--- a/src/modules/ray/ray_scene.c
+++ b/src/modules/ray/ray_render.c
@@ -12,13 +12,20 @@
 #define MAX_RECURSION_DEPTH	4
 #define MIN_RELEVANCE		0.05f
 
+typedef struct ray_render_t {
+	const ray_scene_t	*scene;		/* scene being rendered */
+	const ray_camera_t	*camera;	/* camera rendering the scene */
+
+	ray_color_t		ambient_light;
+	ray_camera_frame_t	frame;
+} ray_render_t;
 
 /* 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, unsigned depth, ray_ray_t *ray, float distance)
+static inline int ray_is_obstructed(ray_render_t *render, unsigned depth, ray_ray_t *ray, float distance)
 {
 	ray_object_t	*object;
 
-	for (object = scene->objects; object->type; object++) {
+	for (object = render->scene->objects; object->type; object++) {
 		float	ood;
 
 		if (ray_object_intersects_ray(object, depth, ray, &ood) &&
@@ -32,14 +39,14 @@ static inline int ray_is_obstructed(ray_scene_t *scene, unsigned depth, ray_ray_
 
 
 /* shadow test */
-static inline int point_is_shadowed(ray_scene_t *scene, unsigned depth, ray_3f_t *light_direction, float distance, ray_3f_t *point)
+static inline int point_is_shadowed(ray_render_t *render, unsigned depth, ray_3f_t *light_direction, float distance, ray_3f_t *point)
 {
 	ray_ray_t	shadow_ray;
 
 	shadow_ray.direction = *light_direction;
 	shadow_ray.origin = *point;
 
-	if (ray_is_obstructed(scene, depth + 1, &shadow_ray, distance))
+	if (ray_is_obstructed(render, depth + 1, &shadow_ray, distance))
 		return 1;
 
 	return 0;
@@ -57,21 +64,21 @@ static inline float approx_powf(float x, float y)
 
 
 /* Determine the color @ distance on ray on object viewed from origin */
-static inline ray_color_t shade_intersection(ray_scene_t *scene, ray_object_t *object, ray_ray_t *ray, ray_3f_t *intersection, ray_3f_t *normal, unsigned depth, float *res_reflectivity)
+static inline ray_color_t shade_intersection(ray_render_t *render, ray_object_t *object, ray_ray_t *ray, ray_3f_t *intersection, ray_3f_t *normal, unsigned depth, float *res_reflectivity)
 {
 	ray_surface_t	surface = ray_object_surface(object, intersection);
-	ray_color_t	color = ray_3f_mult(&surface.color, &scene->_prepared.ambient_light);
+	ray_color_t	color = ray_3f_mult(&surface.color, &render->ambient_light);
 	ray_object_t	*light;
 
 	/* visit lights for shadows and illumination */
-	for (light = scene->lights; light->type; light++) {
+	for (light = render->scene->lights; light->type; light++) {
 		ray_3f_t	lvec = ray_3f_sub(&light->light.emitter.point.center, intersection);
 		float		ldist = ray_3f_length(&lvec);
 		float		lvec_normal_dot;
 
 		lvec = ray_3f_mult_scalar(&lvec, (1.0f / ldist)); /* normalize lvec */
 #if 1
-		if (point_is_shadowed(scene, depth, &lvec, ldist, intersection))
+		if (point_is_shadowed(render, depth, &lvec, ldist, intersection))
 			continue;
 #endif
 		lvec_normal_dot = ray_3f_dot(normal, &lvec);
@@ -109,13 +116,13 @@ static inline ray_color_t shade_intersection(ray_scene_t *scene, ray_object_t *o
 }
 
 
-static inline ray_object_t * find_nearest_intersection(ray_scene_t *scene, ray_object_t *reflector, ray_ray_t *ray, unsigned depth, float *res_distance)
+static inline ray_object_t * find_nearest_intersection(ray_render_t *render, ray_object_t *reflector, ray_ray_t *ray, unsigned depth, float *res_distance)
 {
 	ray_object_t	*nearest_object = NULL;
 	float		nearest_object_distance = INFINITY;
 	ray_object_t	*object;
 
-	for (object = scene->objects; object->type; object++) {
+	for (object = render->scene->objects; object->type; object++) {
 		float		distance;
 
 		/* Don't bother checking if a reflected ray intersects the object reflecting it,
@@ -140,7 +147,7 @@ static inline ray_object_t * find_nearest_intersection(ray_scene_t *scene, ray_o
 }
 
 
-static inline ray_color_t trace_ray(ray_scene_t *scene, ray_ray_t *primary_ray)
+static inline ray_color_t trace_ray(ray_render_t *render, ray_ray_t *primary_ray)
 {
 	ray_color_t	color = { .x = 0.0f, .y = 0.0f, .z = 0.0f };
 	ray_3f_t	intersection, normal;
@@ -165,7 +172,7 @@ static inline ray_color_t trace_ray(ray_scene_t *scene, ray_ray_t *primary_ray)
 			ray = &reflected_ray;
 		}
 
-		nearest_object = find_nearest_intersection(scene, reflector, ray, depth, &nearest_distance);
+		nearest_object = find_nearest_intersection(render, reflector, ray, depth, &nearest_distance);
 		if (nearest_object) {
 			ray_3f_t	more_color;
 			ray_3f_t	rvec;
@@ -174,7 +181,7 @@ static inline ray_color_t trace_ray(ray_scene_t *scene, ray_ray_t *primary_ray)
 			intersection = ray_3f_add(&ray->origin, &rvec);
 			normal = ray_object_normal(nearest_object, &intersection);
 
-			more_color = shade_intersection(scene, nearest_object, ray, &intersection, &normal, depth, &reflectivity);
+			more_color = shade_intersection(render, nearest_object, ray, &intersection, &normal, depth, &reflectivity);
 			more_color = ray_3f_mult_scalar(&more_color, relevance);
 			color = ray_3f_add(&color, &more_color);
 		}
@@ -186,16 +193,16 @@ static inline ray_color_t trace_ray(ray_scene_t *scene, ray_ray_t *primary_ray)
 }
 
 
-void ray_scene_render_fragment(ray_scene_t *scene, fb_fragment_t *fb_fragment)
+void ray_render_trace_fragment(ray_render_t *render, fb_fragment_t *fb_fragment)
 {
 	uint32_t		*buf = fb_fragment->buf;
 	ray_camera_fragment_t	fragment;
 	ray_ray_t		ray;
 
-	ray_camera_fragment_begin(&scene->_prepared.frame, fb_fragment, &ray, &fragment);
+	ray_camera_fragment_begin(&render->frame, fb_fragment, &ray, &fragment);
 	do {
 		do {
-			*buf = ray_color_to_uint32_rgb(trace_ray(scene, &ray));
+			*buf = ray_color_to_uint32_rgb(trace_ray(render, &ray));
 			buf++;
 		} while (ray_camera_fragment_x_step(&fragment));
 
@@ -207,13 +214,29 @@ void ray_scene_render_fragment(ray_scene_t *scene, fb_fragment_t *fb_fragment)
 /* prepare the scene for rendering with camera, must be called whenever anything in the scene+camera pair has been changed. */
 /* this is basically a time for the raytracer to precompute whatever it can which otherwise ends up occurring per-ray */
 /* the camera is included so primary rays which all have a common origin may be optimized for */
-void ray_scene_prepare(ray_scene_t *scene, ray_camera_t *camera)
+ray_render_t * ray_render_new(ray_scene_t *scene, ray_camera_t *camera)
 {
+	ray_render_t	*render;
 	ray_object_t	*object;
 
-	scene->_prepared.ambient_light = ray_3f_mult_scalar(&scene->ambient_color, scene->ambient_brightness);
-	ray_camera_frame_prepare(camera, &scene->_prepared.frame);
+	render = malloc(sizeof(ray_render_t));
+	if (!render)
+		return NULL;
+
+	render->scene = scene;
+	render->camera = camera;
+
+	render->ambient_light = ray_3f_mult_scalar(&scene->ambient_color, scene->ambient_brightness);
+	ray_camera_frame_prepare(camera, &render->frame);
 
 	for (object = scene->objects; object->type; object++)
 		ray_object_prepare(object, camera);
+
+	return render;
+}
+
+
+void ray_render_free(ray_render_t *render)
+{
+	free(render);
 }
diff --git a/src/modules/ray/ray_render.h b/src/modules/ray/ray_render.h
new file mode 100644
index 0000000..a6d6c67
--- /dev/null
+++ b/src/modules/ray/ray_render.h
@@ -0,0 +1,15 @@
+#ifndef _RAY_RENDER_H
+#define _RAY_RENDER_H
+
+#include "fb.h"
+
+#include "ray_camera.h"
+#include "ray_scene.h"
+
+typedef struct ray_render_t ray_render_t;
+
+ray_render_t * ray_render_new(ray_scene_t *scene, ray_camera_t *camera);
+void ray_render_free(ray_render_t *render);
+void ray_render_trace_fragment(ray_render_t *render, fb_fragment_t *fb_fragment);
+
+#endif
diff --git a/src/modules/ray/ray_scene.h b/src/modules/ray/ray_scene.h
index 5c7cd5e..ff9c440 100644
--- a/src/modules/ray/ray_scene.h
+++ b/src/modules/ray/ray_scene.h
@@ -1,28 +1,16 @@
 #ifndef _RAY_SCENE_H
 #define _RAY_SCENE_H
 
-#include "fb.h"
-
-#include "ray_camera.h"
 #include "ray_color.h"
-#include "ray_ray.h"
 
 typedef union ray_object_t ray_object_t;
 
 typedef struct ray_scene_t {
-	ray_object_t		*objects;
-	ray_object_t		*lights;
-
-	ray_color_t		ambient_color;
-	float			ambient_brightness;
+	ray_object_t	*objects;
+	ray_object_t	*lights;
 
-	struct {
-		ray_color_t		ambient_light;
-		ray_camera_frame_t	frame;
-	} _prepared;
+	ray_color_t	ambient_color;
+	float		ambient_brightness;
 } ray_scene_t;
 
-void ray_scene_prepare(ray_scene_t *scene, ray_camera_t *camera);
-void ray_scene_render_fragment(ray_scene_t *scene, fb_fragment_t *fb_fragment);
-
 #endif