143 lines
4.3 KiB
C
143 lines
4.3 KiB
C
/*
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Copyright (C) 2001-2006, William Joseph.
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All Rights Reserved.
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This file is part of GtkRadiant.
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GtkRadiant is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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GtkRadiant is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GtkRadiant; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "mathlib.h"
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#include <float.h>
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vec3_t identity = { 0,0,0 };
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void ray_construct_for_vec3( ray_t *ray, const vec3_t origin, const vec3_t direction ){
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VectorCopy( origin, ray->origin );
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VectorCopy( direction, ray->direction );
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}
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void ray_transform( ray_t *ray, const m4x4_t matrix ){
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m4x4_transform_point( matrix, ray->origin );
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m4x4_transform_normal( matrix, ray->direction );
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}
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vec_t ray_intersect_point( const ray_t *ray, const vec3_t point, vec_t epsilon, vec_t divergence ){
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vec3_t displacement;
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vec_t depth;
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// calc displacement of test point from ray origin
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VectorSubtract( point, ray->origin, displacement );
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// calc length of displacement vector along ray direction
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depth = DotProduct( displacement, ray->direction );
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if ( depth < 0.0f ) {
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return (vec_t)FLT_MAX;
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}
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// calc position of closest point on ray to test point
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VectorMA( ray->origin, depth, ray->direction, displacement );
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// calc displacement of test point from closest point
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VectorSubtract( point, displacement, displacement );
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// calc length of displacement, subtract depth-dependant epsilon
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if ( VectorLength( displacement ) - ( epsilon + ( depth * divergence ) ) > 0.0f ) {
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return (vec_t)FLT_MAX;
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}
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return depth;
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}
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// Tomas Moller and Ben Trumbore. Fast, minimum storage ray-triangle intersection. Journal of graphics tools, 2(1):21-28, 1997
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const double EPSILON = 0.000001;
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vec_t ray_intersect_triangle( const ray_t *ray, qboolean bCullBack, const vec3_t vert0, const vec3_t vert1, const vec3_t vert2 ){
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float edge1[3], edge2[3], tvec[3], pvec[3], qvec[3];
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float det,inv_det;
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float u, v;
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vec_t depth = (vec_t)FLT_MAX;
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/* find vectors for two edges sharing vert0 */
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VectorSubtract( vert1, vert0, edge1 );
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VectorSubtract( vert2, vert0, edge2 );
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/* begin calculating determinant - also used to calculate U parameter */
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CrossProduct( ray->direction, edge2, pvec );
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/* if determinant is near zero, ray lies in plane of triangle */
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det = DotProduct( edge1, pvec );
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if ( bCullBack == qtrue ) {
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if ( det < EPSILON ) {
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return depth;
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}
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// calculate distance from vert0 to ray origin
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VectorSubtract( ray->origin, vert0, tvec );
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// calculate U parameter and test bounds
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u = DotProduct( tvec, pvec );
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if ( u < 0.0 || u > det ) {
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return depth;
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}
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// prepare to test V parameter
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CrossProduct( tvec, edge1, qvec );
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// calculate V parameter and test bounds
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v = DotProduct( ray->direction, qvec );
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if ( v < 0.0 || u + v > det ) {
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return depth;
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}
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// calculate t, scale parameters, ray intersects triangle
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depth = DotProduct( edge2, qvec );
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inv_det = 1.0f / det;
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depth *= inv_det;
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//u *= inv_det;
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//v *= inv_det;
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}
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else
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{
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/* the non-culling branch */
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if ( det > -EPSILON && det < EPSILON ) {
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return depth;
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}
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inv_det = 1.0f / det;
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/* calculate distance from vert0 to ray origin */
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VectorSubtract( ray->origin, vert0, tvec );
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/* calculate U parameter and test bounds */
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u = DotProduct( tvec, pvec ) * inv_det;
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if ( u < 0.0 || u > 1.0 ) {
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return depth;
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}
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/* prepare to test V parameter */
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CrossProduct( tvec, edge1, qvec );
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/* calculate V parameter and test bounds */
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v = DotProduct( ray->direction, qvec ) * inv_det;
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if ( v < 0.0 || u + v > 1.0 ) {
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return depth;
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}
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/* calculate t, ray intersects triangle */
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depth = DotProduct( edge2, qvec ) * inv_det;
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}
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return depth;
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}
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vec_t ray_intersect_plane( const ray_t* ray, const vec3_t normal, vec_t dist ){
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return -( DotProduct( normal, ray->origin ) - dist ) / DotProduct( ray->direction, normal );
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}
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