server/cull.c

   1 /*
   2  * cull.c
   3  *
   4  * Copyright (C) 2004-2011  Simon Wunderlich <dotslash@packetmixer.de>
   5  * code originated from  http://www.racer.nl/reference/vfc.htm
   6  * which is (C) Ruud van Gaal
   7  *
   8  * This file is part of s3d, a 3d network display server.
   9  * See http://s3d.berlios.de/ for more updates.
  10  *
  11  * s3d is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * s3d is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with s3d; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  24  */
  25
  26 #include "global.h"
  27 #include <math.h>               /* sqrt() */
  28 #if G_SDL
  29 #include <SDL_opengl.h>         /*  glGetFloatv */
  30 #else
  31 #include <GL/gl.h>              /*  glGetFloatv */
  32 #endif
  33 struct t_plane {
  34         struct t_vertex n;
  35         float d;
  36 };
  37 #define LEFT 0
  38 #define RIGHT 1
  39 #define TOP  2
  40 #define BOTTOM 3
  41 #define PNEAR 4
  42 #define PFAR 5
  43
  44 static struct t_plane frustumPlane[6];
  45
  46 void cull_get_planes(void)
  47 {
  48         t_mtrx m, mproj, mmodel;
  49         struct t_plane *p;
  50         int i;
  51         float d;
  52
  53         /* get matrices from opengl */
  54         glGetFloatv(GL_MODELVIEW_MATRIX, mmodel);
  55         glGetFloatv(GL_PROJECTION_MATRIX, mproj);
  56
  57         mySetMatrix(mproj);
  58         myMultMatrix(mmodel);
  59         myGetMatrix(m);         /* multiply and have the result in m */
  60
  61         p = &frustumPlane[RIGHT];
  62         p->n.x = m[3] - m[0];
  63         p->n.y = m[7] - m[4];
  64         p->n.z = m[11] - m[8];
  65         p->d = m[15] - m[12];
  66
  67         p = &frustumPlane[LEFT];
  68         p->n.x = m[3] + m[0];
  69         p->n.y = m[7] + m[4];
  70         p->n.z = m[11] + m[8];
  71         p->d = m[15] + m[12];
  72
  73         p = &frustumPlane[BOTTOM];
  74         p->n.x = m[3] + m[1];
  75         p->n.y = m[7] + m[5];
  76         p->n.z = m[11] + m[9];
  77         p->d = m[15] + m[13];
  78
  79         p = &frustumPlane[TOP];
  80         p->n.x = m[3] - m[1];
  81         p->n.y = m[7] - m[5];
  82         p->n.z = m[11] - m[9];
  83         p->d = m[15] - m[13];
  84
  85         p = &frustumPlane[PFAR];
  86         p->n.x = m[3] - m[2];
  87         p->n.y = m[7] - m[6];
  88         p->n.z = m[11] - m[10];
  89         p->d = m[15] - m[14];
  90
  91         p = &frustumPlane[PNEAR];
  92         p->n.x = m[3] + m[2];
  93         p->n.y = m[7] + m[6];
  94         p->n.z = m[11] + m[10];
  95         p->d = m[15] + m[14];
  96
  97         /* Normalize all plane normals */
  98         for (i = 0; i < 6; i++) {
  99                 p = &frustumPlane[i];
 100                 d = sqrt(p->n.x * p->n.x + p->n.y * p->n.y + p->n.z * p->n.z);
 101                 if (d != 0.0) {
 102                         p->n.x /= d;
 103                         p->n.y /= d;
 104                         p->n.z /= d;
 105                         p->d /= d;
 106                 }
 107         }
 108 }
 109
 110 int cull_sphere_in_frustum(struct t_vertex *center, float radius)
 111 {
 112         int i;
 113         struct t_plane *p;
 114         for (i = 0; i < 6; i++) {
 115                 p = &frustumPlane[i];
 116                 if (p->n.x * center->x + p->n.y * center->y + p->n.z * center->z + p->d <= -radius) {
 117                         return 0;       /* sorry, no ... */
 118                 }
 119         }
 120         return 1;               /* it's inside */
 121 }