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authorTavian Barnes <tavianator@gmail.com>2010-05-04 16:38:33 -0600
committerTavian Barnes <tavianator@gmail.com>2010-05-04 16:38:33 -0600
commit72a0b0d511822d7521e2d44f6e468f3d1870521e (patch)
tree0e0c61fff98f984c41bd928260c96206b77e5d4b
parent4b7df6a2685fe973d9d31d884407df4f669b5606 (diff)
downloaddimension-72a0b0d511822d7521e2d44f6e468f3d1870521e.tar.xz
Optimize cube intersection function a bit.
-rw-r--r--libdimension/cube.c141
1 files changed, 82 insertions, 59 deletions
diff --git a/libdimension/cube.c b/libdimension/cube.c
index 396049d..4c09d04 100644
--- a/libdimension/cube.c
+++ b/libdimension/cube.c
@@ -19,7 +19,7 @@
*************************************************************************/
#include "dimension.h"
-#include <math.h> /* For sqrt */
+#include <math.h>
/*
* Cube
@@ -49,83 +49,106 @@ static bool
dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_line line,
dmnsn_intersection *intersection)
{
- dmnsn_line line_trans = dmnsn_transform_line(cube->trans_inv, line);
+ /* Clip the given line against the X, Y, and Z slabs */
- double t = -1.0, t_temp;
- dmnsn_vector p, normal;
+ dmnsn_line line_trans = dmnsn_transform_line(cube->trans_inv, line);
- /* Six ray-plane intersection tests (x, y, z) = +/- 1.0 */
+ dmnsn_vector nmin, nmax;
+ double tmin = -INFINITY, tmax = INFINITY;
if (line_trans.n.x != 0.0) {
- /* x = -1.0 */
- t_temp = (-1.0 - line_trans.x0.x)/line_trans.n.x;
- p = dmnsn_line_point(line_trans, t_temp);
- if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
- && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
- {
- t = t_temp;
- normal = dmnsn_new_vector(-1.0, 0.0, 0.0);
- }
+ double tx1 = (-1.0 - line_trans.x0.x)/line_trans.n.x;
+ double tx2 = (+1.0 - line_trans.x0.x)/line_trans.n.x;
- /* x = 1.0 */
- t_temp = (1.0 - line_trans.x0.x)/line_trans.n.x;
- p = dmnsn_line_point(line_trans, t_temp);
- if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
- && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
- {
- t = t_temp;
- normal = dmnsn_new_vector(1.0, 0.0, 0.0);
+ if (tx1 < tx2) {
+ if (tx1 > tmin) {
+ tmin = tx1;
+ nmin = dmnsn_new_vector(-1.0, 0.0, 0.0);
+ }
+ if (tx2 < tmax) {
+ tmax = tx2;
+ nmax = dmnsn_new_vector(+1.0, 0.0, 0.0);
+ }
+ } else {
+ if (tx2 > tmin) {
+ tmin = tx2;
+ nmin = dmnsn_new_vector(+1.0, 0.0, 0.0);
+ }
+ if (tx1 < tmax) {
+ tmax = tx1;
+ nmax = dmnsn_new_vector(-1.0, 0.0, 0.0);
+ }
}
+
+ if (tmin > tmax)
+ return false;
}
if (line_trans.n.y != 0.0) {
- /* y = -1.0 */
- t_temp = (-1.0 - line_trans.x0.y)/line_trans.n.y;
- p = dmnsn_line_point(line_trans, t_temp);
- if (p.x >= -1.0 && p.x <= 1.0 && p.z >= -1.0 && p.z <= 1.0
- && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
- {
- t = t_temp;
- normal = dmnsn_new_vector(0.0, -1.0, 0.0);
- }
+ double ty1 = (-1.0 - line_trans.x0.y)/line_trans.n.y;
+ double ty2 = (+1.0 - line_trans.x0.y)/line_trans.n.y;
- /* y = 1.0 */
- t_temp = (1.0 - line_trans.x0.y)/line_trans.n.y;
- p = dmnsn_line_point(line_trans, t_temp);
- if (p.x >= -1.0 && p.x <= 1.0 && p.z >= -1.0 && p.z <= 1.0
- && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
- {
- t = t_temp;
- normal = dmnsn_new_vector(0.0, 1.0, 0.0);
+ if (ty1 < ty2) {
+ if (ty1 > tmin) {
+ tmin = ty1;
+ nmin = dmnsn_new_vector(0.0, -1.0, 0.0);
+ }
+ if (ty2 < tmax) {
+ tmax = ty2;
+ nmax = dmnsn_new_vector(0.0, +1.0, 0.0);
+ }
+ } else {
+ if (ty2 > tmin) {
+ tmin = ty2;
+ nmin = dmnsn_new_vector(0.0, +1.0, 0.0);
+ }
+ if (ty1 < tmax) {
+ tmax = ty1;
+ nmax = dmnsn_new_vector(0.0, -1.0, 0.0);
+ }
}
+
+ if (tmin > tmax)
+ return false;
}
if (line_trans.n.z != 0.0) {
- /* z = -1.0 */
- t_temp = (-1.0 - line_trans.x0.z)/line_trans.n.z;
- p = dmnsn_line_point(line_trans, t_temp);
- if (p.x >= -1.0 && p.x <= 1.0 && p.y >= -1.0 && p.y <= 1.0
- && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
- {
- t = t_temp;
- normal = dmnsn_new_vector(0.0, 0.0, -1.0);
- }
+ double tz1 = (-1.0 - line_trans.x0.z)/line_trans.n.z;
+ double tz2 = (+1.0 - line_trans.x0.z)/line_trans.n.z;
- /* z = 1.0 */
- t_temp = (1.0 - line_trans.x0.z)/line_trans.n.z;
- p = dmnsn_line_point(line_trans, t_temp);
- if (p.x >= -1.0 && p.x <= 1.0 && p.y >= -1.0 && p.y <= 1.0
- && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
- {
- t = t_temp;
- normal = dmnsn_new_vector(0.0, 0.0, 1.0);
+ if (tz1 < tz2) {
+ if (tz1 > tmin) {
+ tmin = tz1;
+ nmin = dmnsn_new_vector(0.0, 0.0, -1.0);
+ }
+ if (tz2 < tmax) {
+ tmax = tz2;
+ nmax = dmnsn_new_vector(0.0, 0.0, +1.0);
+ }
+ } else {
+ if (tz2 > tmin) {
+ tmin = tz2;
+ nmin = dmnsn_new_vector(0.0, 0.0, +1.0);
+ }
+ if (tz1 < tmax) {
+ tmax = tz1;
+ nmax = dmnsn_new_vector(0.0, 0.0, -1.0);
+ }
}
+
+ if (tmin > tmax)
+ return false;
+ }
+
+ if (tmin < 0.0) {
+ tmin = tmax;
+ nmin = nmax;
}
- if (t >= 0.0) {
+ if (tmin >= 0.0) {
intersection->ray = line;
- intersection->t = t;
- intersection->normal = dmnsn_transform_normal(cube->trans, normal);
+ intersection->t = tmin;
+ intersection->normal = dmnsn_transform_normal(cube->trans, nmin);
intersection->texture = cube->texture;
intersection->interior = cube->interior;
return true;