gtkradiant/libs/mathlib/ray.c

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/*
Copyright (C) 1999-2007 id Software, Inc. and contributors.
For a list of contributors, see the accompanying CONTRIBUTORS file.
This file is part of GtkRadiant.
GtkRadiant is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
GtkRadiant is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GtkRadiant; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "mathlib.h"
/*! for memcpy */
#include <memory.h>
vec3_t identity = { 0,0,0 };
void ray_construct_for_vec3(ray_t *ray, const vec3_t origin, const vec3_t direction)
{
VectorCopy(origin, ray->origin);
VectorCopy(direction, ray->direction);
}
void ray_transform(ray_t *ray, const m4x4_t matrix)
{
m4x4_transform_point(matrix, ray->origin);
m4x4_transform_normal(matrix, ray->direction);
}
vec_t ray_intersect_point(const ray_t *ray, const vec3_t point, vec_t epsilon, vec_t divergence)
{
vec3_t displacement;
vec_t depth;
// calc displacement of test point from ray origin
VectorSubtract(point, ray->origin, displacement);
// calc length of displacement vector along ray direction
depth = DotProduct(displacement, ray->direction);
if(depth < 0.0f) return (vec_t)VEC_MAX;
// calc position of closest point on ray to test point
VectorMA (ray->origin, depth, ray->direction, displacement);
// calc displacement of test point from closest point
VectorSubtract(point, displacement, displacement);
// calc length of displacement, subtract depth-dependant epsilon
if (VectorLength(displacement) - (epsilon + (depth * divergence)) > 0.0f) return (vec_t)VEC_MAX;
return depth;
}
// Tomas Moller and Ben Trumbore. Fast, minimum storage ray-triangle intersection. Journal of graphics tools, 2(1):21-28, 1997
#define EPSILON 0.000001
vec_t ray_intersect_triangle(const ray_t *ray, qboolean bCullBack, const vec3_t vert0, const vec3_t vert1, const vec3_t vert2)
{
float edge1[3], edge2[3], tvec[3], pvec[3], qvec[3];
float det,inv_det;
float u, v;
vec_t depth = (vec_t)VEC_MAX;
/* find vectors for two edges sharing vert0 */
VectorSubtract(vert1, vert0, edge1);
VectorSubtract(vert2, vert0, edge2);
/* begin calculating determinant - also used to calculate U parameter */
CrossProduct(ray->direction, edge2, pvec);
/* if determinant is near zero, ray lies in plane of triangle */
det = DotProduct(edge1, pvec);
if (bCullBack == qtrue)
{
if (det < EPSILON)
return depth;
// calculate distance from vert0 to ray origin
VectorSubtract(ray->origin, vert0, tvec);
// calculate U parameter and test bounds
u = DotProduct(tvec, pvec);
if (u < 0.0 || u > det)
return depth;
// prepare to test V parameter
CrossProduct(tvec, edge1, qvec);
// calculate V parameter and test bounds
v = DotProduct(ray->direction, qvec);
if (v < 0.0 || u + v > det)
return depth;
// calculate t, scale parameters, ray intersects triangle
depth = DotProduct(edge2, qvec);
inv_det = 1.0f / det;
depth *= inv_det;
//u *= inv_det;
//v *= inv_det;
}
else
{
/* the non-culling branch */
if (det > -EPSILON && det < EPSILON)
return depth;
inv_det = 1.0f / det;
/* calculate distance from vert0 to ray origin */
VectorSubtract(ray->origin, vert0, tvec);
/* calculate U parameter and test bounds */
u = DotProduct(tvec, pvec) * inv_det;
if (u < 0.0 || u > 1.0)
return depth;
/* prepare to test V parameter */
CrossProduct(tvec, edge1, qvec);
/* calculate V parameter and test bounds */
v = DotProduct(ray->direction, qvec) * inv_det;
if (v < 0.0 || u + v > 1.0)
return depth;
/* calculate t, ray intersects triangle */
depth = DotProduct(edge2, qvec) * inv_det;
}
return depth;
}