ray: cleanup ray_camera_frame_t fragments

Previously every fb_fragment_t (and thus thread) was constructing
its own ray_camera_frame_t view into the scene, duplicating some
work.

Instead introduce ray_camera_fragment_t to encapsulate the truly
per-fragment state and make ray_scene_render_fragment() operate
on just this stuff with a reference to a shared
ray_camera_frame_t prepared once per-frame.

Some minor ray_camera.c cleanups sneak in as well (prefer multiply
instead of divide, whitespace cleanups...)

1 files changed, 33 insertions, 26 deletions

diff --git a/src/modules/ray/ray_camera.h b/src/modules/ray/ray_camera.h
index 191d614..889beb9 100644
--- a/src/modules/ray/ray_camera.h
+++ b/src/modules/ray/ray_camera.h
@@ -21,55 +21,62 @@ typedef struct ray_camera_t {
 
 typedef struct ray_camera_frame_t {
 	ray_camera_t	*camera;		/* the camera supplied to frame_begin() */
-	fb_fragment_t	*fragment;		/* the fragment supplied to frame_begin() */
-	ray_ray_t	*ray;			/* the ray supplied to frame_begin(), which gets updated as we step through the frame. */
 
 	ray_3f_t	nw, ne, sw, se;		/* directions pointing through the corners of the frame fragment */
-	ray_3f_t	cur_w, cur_e;		/* current row's west and east ends */
-	float		x_alpha, y_alpha;	/* interpolation position along the x and y axis */
 	float		x_delta, y_delta;	/* interpolation step delta along the x and y axis */
-	unsigned	x, y;			/* integral position within frame fragment */
 } ray_camera_frame_t;
 
 
-void ray_camera_frame_begin(ray_camera_t *camera, fb_fragment_t *fragment, ray_ray_t *ray, ray_camera_frame_t *frame);
+typedef struct ray_camera_fragment_t {
+	ray_camera_frame_t	*frame;			/* the frame supplied to fragment_begin() */
+	fb_fragment_t		*fb_fragment;		/* the fragment supplied to fragment_begin() */
+	ray_ray_t		*ray;			/* the ray supplied to frame_begin(), which gets updated as we step through the frame. */
 
+	ray_3f_t		cur_w, cur_e;		/* current row's west and east ends */
+	float			x_alpha, y_alpha;	/* interpolation position along the x and y axis */
+	unsigned		x, y;			/* integral position within frame fragment */
+} ray_camera_fragment_t;
 
-/* Step the ray through the frame on the x axis, returns 1 when rays remain on this axis, 0 at the end. */
-/* When 1 is returned, frame->ray is left pointing through the new coordinate. */
-static inline int ray_camera_frame_x_step(ray_camera_frame_t *frame)
+
+void ray_camera_frame_prepare(ray_camera_t *camera, ray_camera_frame_t *res_frame);
+void ray_camera_fragment_begin(ray_camera_frame_t *frame, fb_fragment_t *fb_fragment, ray_ray_t *res_ray, ray_camera_fragment_t *res_fragment);
+
+
+/* Step the ray through the fragment on the x axis, returns 1 when rays remain on this axis, 0 at the end. */
+/* When 1 is returned, fragment->ray is left pointing through the new coordinate. */
+static inline int ray_camera_fragment_x_step(ray_camera_fragment_t *fragment)
 {
-	frame->x++;
+	fragment->x++;
 
-	if (frame->x >= frame->fragment->width) {
-		frame->x = 0;
-		frame->x_alpha = frame->x_delta * (float)frame->fragment->x;
+	if (fragment->x >= fragment->fb_fragment->width) {
+		fragment->x = 0;
+		fragment->x_alpha = fragment->frame->x_delta * (float)fragment->fb_fragment->x;
 		return 0;
 	}
 
-	frame->x_alpha += frame->x_delta;
-	frame->ray->direction = ray_3f_nlerp(&frame->cur_w, &frame->cur_e, frame->x_alpha);
+	fragment->x_alpha += fragment->frame->x_delta;
+	fragment->ray->direction = ray_3f_nlerp(&fragment->cur_w, &fragment->cur_e, fragment->x_alpha);
 
 	return 1;
 }
 
 
-/* Step the ray through the frame on the y axis, returns 1 when rays remain on this axis, 0 at the end. */
-/* When 1 is returned, frame->ray is left pointing through the new coordinate. */
-static inline int ray_camera_frame_y_step(ray_camera_frame_t *frame)
+/* Step the ray through the fragment on the y axis, returns 1 when rays remain on this axis, 0 at the end. */
+/* When 1 is returned, fragment->ray is left pointing through the new coordinate. */
+static inline int ray_camera_fragment_y_step(ray_camera_fragment_t *fragment)
 {
-	frame->y++;
+	fragment->y++;
 
-	if (frame->y >= frame->fragment->height) {
-		frame->y = 0;
-		frame->y_alpha = frame->y_delta * (float)frame->fragment->y;
+	if (fragment->y >= fragment->fb_fragment->height) {
+		fragment->y = 0;
+		fragment->y_alpha = fragment->frame->y_delta * (float)fragment->fb_fragment->y;
 		return 0;
 	}
 
-	frame->y_alpha += frame->y_delta;
-	frame->cur_w = ray_3f_lerp(&frame->nw, &frame->sw, frame->y_alpha);
-	frame->cur_e = ray_3f_lerp(&frame->ne, &frame->se, frame->y_alpha);
-	frame->ray->direction = ray_3f_nlerp(&frame->cur_w, &frame->cur_e, frame->x_alpha);
+	fragment->y_alpha += fragment->frame->y_delta;
+	fragment->cur_w = ray_3f_lerp(&fragment->frame->nw, &fragment->frame->sw, fragment->y_alpha);
+	fragment->cur_e = ray_3f_lerp(&fragment->frame->ne, &fragment->frame->se, fragment->y_alpha);
+	fragment->ray->direction = ray_3f_nlerp(&fragment->cur_w, &fragment->cur_e, fragment->x_alpha);
 
 	return 1;
 }