1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102
|
/* Goxel 3D voxels editor
*
* copyright (c) 2015 Guillaume Chereau <guillaume@noctua-software.com>
*
* Goxel 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 3 of the License, or (at your option) any later
* version.
* Goxel 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
* goxel. If not, see <http://www.gnu.org/licenses/>.
*/
#include "goxel.h"
/* A plane is defined as the 4x4 matrix to transform from the plane local
* coordinate into global coordinates:
*
*
* n
* ^ v
* | ^ . . . . .
* | / .
* | / .
* |/ .
* +---------> u
* P
*
* Here the plane defined by the point P and vectors u and v with normal n,
* will have a matrix like this:
*
* [ux uy yz 0]
* [vx vy vz 0]
* [nx ny nz 0]
* [px py pz 1]
*
* This representation has several advantages: we can access the plane unitary
* vectors, normal, and origin without any computation. I used an union so
* that those values can be access directly as u, v, n, and p. For the
* vec4 version we can also use u4, v4, n4, and p4.
*
* It is also trivial to transform a point in the plane into world
* coordinates, simply by using matrix computation.
*
*/
static const float plane_null[4][4] = {};
static inline void plane_from_vectors(float plane[4][4],
const float pos[3], const float u[3], const float v[3])
{
mat4_set_identity(plane);
vec3_copy(u, plane[0]);
vec3_copy(v, plane[1]);
vec3_cross(u, v, plane[2]);
vec3_copy(pos, plane[3]);
}
static inline bool plane_is_null(const float p[4][4]) {
return p[3][3] == 0;
}
// Check if a plane intersect a line.
// if out is set, it receive the position of the intersection in the
// plane local coordinates. Apply the plane matrix on it to get the
// object coordinate position.
static inline bool plane_line_intersection(const float plane[4][4],
const float p[3], const float n[3], float out[3])
{
float v[3], m[4][4];
mat4_set_identity(m);
vec3_copy(plane[0], m[0]);
vec3_copy(plane[1], m[1]);
vec3_copy(n, m[2]);
if (!mat4_invert(m, m)) return false;
if (out) {
vec3_sub(p, plane[3], v);
mat4_mul_vec3(m, v, out);
out[2] = 0;
}
return true;
}
static inline void plane_from_normal(float plane[4][4],
const float pos[3], const float n[3])
{
int i;
const float AXES[][3] = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}};
mat4_set_identity(plane);
vec3_copy(pos, plane[3]);
vec3_normalize(n, plane[2]);
for (i = 0; i < 3; i++) {
vec3_cross(plane[2], AXES[i], plane[0]);
if (vec3_norm2(plane[0]) > 0) break;
}
vec3_cross(plane[2], plane[0], plane[1]);
}
|