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
|
/*
ssystem 1.6
Copyright (C) 1997-1999 Raul Alonso <amil@las.es>
This program 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.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "ssystem.h"
void SunBillBoard( void )
{
double x[4],y[4],z[4];
double alfa,beta;
int i;
#define SIZE RADIUSSCALE(109.0)
x[0]=x[3]=y[0]=y[1]=SIZE;
x[1]=x[2]=y[2]=y[3]=-SIZE;
z[0]=z[1]=z[2]=z[3]=0.0;
/* BILLBOARDING effect, rotates sun tile so it shows always the same face and
angle to camera */
alfa=atan2(camz,camx)-PI/2.0;
beta=atan2(camy,sqrt(camx*camx+camz*camz));
for (i=0;i<4;i++) {
Rotation(beta,1.0,0.0,0.0,&x[i],&y[i],&z[i]);
Rotation(alfa,0.0,1.0,0.0,&x[i],&y[i],&z[i]);
}
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
glBegin(GL_QUADS);
glTexCoord2f(0.0,0.0); glVertex3f(x[0],y[0],z[0]);
glTexCoord2f(0.0,1.0); glVertex3f(x[1],y[1],z[1]);
glTexCoord2f(1.0,1.0); glVertex3f(x[2],y[2],z[2]);
glTexCoord2f(1.0,0.0); glVertex3f(x[3],y[3],z[3]);
glEnd();
glDisable(GL_BLEND);
}
|
