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// SPDX-License-Identifier: GPL-2.0-or-later
/* SPDX-FileCopyrightText: 2004-2015 Simon Wunderlich <sw@simonwunderlich.de>
* code originated from http://www.racer.nl/reference/vfc.htm
* which is (C) Ruud van Gaal
*/
#include "global.h"
#include <math.h> /* sqrt() */
#include <GL/gl.h> /* glGetFloatv */
struct t_plane {
struct t_vertex n;
float d;
};
#define LEFT 0
#define RIGHT 1
#define TOP 2
#define BOTTOM 3
#define PNEAR 4
#define PFAR 5
static struct t_plane frustumPlane[6];
void cull_get_planes(void)
{
t_mtrx m, mproj, mmodel;
struct t_plane *p;
int i;
float d;
/* get matrices from opengl */
glGetFloatv(GL_MODELVIEW_MATRIX, mmodel);
glGetFloatv(GL_PROJECTION_MATRIX, mproj);
mySetMatrix(mproj);
myMultMatrix(mmodel);
myGetMatrix(m); /* multiply and have the result in m */
p = &frustumPlane[RIGHT];
p->n.x = m[3] - m[0];
p->n.y = m[7] - m[4];
p->n.z = m[11] - m[8];
p->d = m[15] - m[12];
p = &frustumPlane[LEFT];
p->n.x = m[3] + m[0];
p->n.y = m[7] + m[4];
p->n.z = m[11] + m[8];
p->d = m[15] + m[12];
p = &frustumPlane[BOTTOM];
p->n.x = m[3] + m[1];
p->n.y = m[7] + m[5];
p->n.z = m[11] + m[9];
p->d = m[15] + m[13];
p = &frustumPlane[TOP];
p->n.x = m[3] - m[1];
p->n.y = m[7] - m[5];
p->n.z = m[11] - m[9];
p->d = m[15] - m[13];
p = &frustumPlane[PFAR];
p->n.x = m[3] - m[2];
p->n.y = m[7] - m[6];
p->n.z = m[11] - m[10];
p->d = m[15] - m[14];
p = &frustumPlane[PNEAR];
p->n.x = m[3] + m[2];
p->n.y = m[7] + m[6];
p->n.z = m[11] + m[10];
p->d = m[15] + m[14];
/* Normalize all plane normals */
for (i = 0; i < 6; i++) {
p = &frustumPlane[i];
d = sqrt(p->n.x * p->n.x + p->n.y * p->n.y + p->n.z * p->n.z);
if (d != 0.0) {
p->n.x /= d;
p->n.y /= d;
p->n.z /= d;
p->d /= d;
}
}
}
int cull_sphere_in_frustum(struct t_vertex *center, float radius)
{
int i;
struct t_plane *p;
for (i = 0; i < 6; i++) {
p = &frustumPlane[i];
if (p->n.x * center->x + p->n.y * center->y + p->n.z * center->z + p->d <= -radius) {
return 0; /* sorry, no ... */
}
}
return 1; /* it's inside */
}
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