diff options
| -rw-r--r-- | libdimension/cube.c | 141 |
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; |