9 unsigned char env_map[TEXRES_X][TEXRES_Y][4];
11 int window_x = 640, window_y = 480;
12 float alpha = 0.0, beta = 0.0;
14 /*****************************************************************/
15 /*****************************************************************/
16 /*****************************************************************/
17 void setColor(float x, float y, float z, float angular_size, float r, float g, float b, float a)
20 float inv_length = 1.0 / sqrt(x*x + y*y + z*z);
21 x *= inv_length; y *= inv_length; z *= inv_length;
22 printf("x = %f, y = %f, z = %f\n", x, y, z);
24 float cos_angular_size = cos(angular_size*3.1415/180.0);
25 printf("cos_angular_size = %f\n", cos_angular_size);
27 for(float tz_sign = -1.0; tz_sign < 3.0; tz_sign += 2.0)
29 for(float tx = -1.0; tx <= 1.0; tx += 0.01)
31 for(float ty = -1.0; ty <= 1.0; ty += 0.01)
33 if ((1.0 - tx*tx - ty*ty)<0.0)
36 float tz = tz_sign * sqrt(1.0 - tx*tx - ty*ty);
38 float cos_phi = x*tx + y*ty + z*tz;
40 if (cos_angular_size < cos_phi)
42 float rx = tx; //mirroring on the z=0 plane
46 float inv_m = 1.0 / (2.0 * sqrt(rx*rx + ry*ry + (rz + 1)*(rz + 1)));
47 int s = (int)(TEXRES_X * (rx * inv_m + 0.5));
48 int t = (int)(TEXRES_Y * (ry * inv_m + 0.5));
50 //seg_fault protection:
52 if (s>=TEXRES_X) s=TEXRES_X-1;
55 if (t>=TEXRES_Y) t=TEXRES_Y-1;
57 env_map[s][t][0] = (unsigned char)(r * 255);
58 env_map[s][t][1] = (unsigned char)(g * 255);
59 env_map[s][t][2] = (unsigned char)(b * 255);
60 env_map[s][t][3] = (unsigned char)(a * 255);
66 /*****************************************************************/
67 /*****************************************************************/
68 /*****************************************************************/
72 glClearColor(0.0, 0.0, 0.0, 0.0);
73 glShadeModel(GL_FLAT);
74 glEnable(GL_DEPTH_TEST);
76 for(int x=0; x<TEXRES_X; x++)
78 for(int y=0; y<TEXRES_Y; y++)
80 env_map[x][y][0] = x; //a few colors
82 env_map[x][y][2] = 128;
83 env_map[x][y][3] = 128;
87 /*****************************************************************/
88 /*****************************************************************/
89 /*****************************************************************/
91 setColor(0.0, 0.0, -1.0 , 23.0, 1.0, 1.0, 1.0, 1.0);
92 setColor(0.7071067, 0.0, -0.7071067, 23.0, 1.0, 0.0, 0.0, 1.0);
93 /*****************************************************************/
94 /*****************************************************************/
95 /*****************************************************************/
97 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
98 glGenTextures(1, &texName);
99 glBindTexture(GL_TEXTURE_2D, texName);
101 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
102 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
103 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
104 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
105 glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, TEXRES_X, TEXRES_Y, 0, GL_RGBA, GL_UNSIGNED_BYTE, env_map);
108 void reshape(int w, int h)
110 window_x = w; window_y = h;
111 glViewport(0, 0, (GLsizei) w, (GLsizei) h);
112 glMatrixMode(GL_PROJECTION);
114 gluPerspective((GLdouble) 60.0, ((GLdouble)w)/((GLdouble)h), (GLdouble) 10.0, (GLdouble) 1000.0);
115 glMatrixMode(GL_MODELVIEW);
117 glTranslatef(0.0, 0.0, -20.0);
122 glClear ( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ) ;
125 glMatrixMode(GL_PROJECTION);
127 gluPerspective((GLdouble) 60.0, (float)window_x/window_y, (GLdouble) 1.0, (GLdouble) 100.0);
128 glMatrixMode(GL_MODELVIEW);
131 glTranslatef(0.0, 0.0, -10.0);
133 glRotatef(alpha, 1.0, 0.0, 0.0);
134 glRotatef(beta, 0.0, 1.0, 0.0);
137 glColor3f(1.0, 1.0, 1.0);
138 glVertex3f(0.0, 0.0, 0.0);
139 glVertex3f(0.0, 0.0, 1.0);
142 /*****************************************************************/
143 /*****************************************************************/
144 /*****************************************************************/
145 glEnable(GL_TEXTURE_2D);
146 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
147 glBindTexture(GL_TEXTURE_2D, texName);
149 glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);
150 glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);
151 glEnable(GL_TEXTURE_GEN_S);
152 glEnable(GL_TEXTURE_GEN_T);
155 glNormal3f(0.0, 0.0, 1.0);
156 glVertex3f(1.0, 1.0, 0.0);
157 glVertex3f(-1.0, 1.0, 0.0);
158 glVertex3f(-1.0, -1.0, 0.0);
159 glVertex3f(1.0, -1.0, 0.0);
165 glNormal3f(0.0, 0.0, 1.0);
166 glVertex3f(0.0, 0.0, 0.0);
170 glDisable(GL_TEXTURE_GEN_S);
171 glDisable(GL_TEXTURE_GEN_T);
172 glDisable(GL_TEXTURE_2D);
173 /*****************************************************************/
174 /*****************************************************************/
175 /*****************************************************************/
177 //show how the map looks like
178 glMatrixMode(GL_PROJECTION);
180 //gluOrtho2D(0.0 -10.0, 1.0 +10.0, -(float)window_x/window_y -10.0,0.0 +10.0);
181 //glOrtho(0.0, 5.0, -5.0, 0.0, -10.0, 10.0);
182 glOrtho(0.0, 5.0*((float)window_x/window_y), -5.0, 0.0, -10.0, 10.0);
183 glMatrixMode(GL_MODELVIEW);
185 glEnable(GL_TEXTURE_2D);
186 glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
187 glBindTexture(GL_TEXTURE_2D, texName);
190 glTexCoord2f(0.0, 0.0); glVertex3f(0.0, 0.0, 0.0);
191 glTexCoord2f(0.0, 1.0); glVertex3f(0.0, -1.0, 0.0);
192 glTexCoord2f(1.0, 1.0); glVertex3f(1.0, -1.0, 0.0);
193 glTexCoord2f(1.0, 0.0); glVertex3f(1.0, 0.0, 0.0);
196 glDisable(GL_TEXTURE_2D);
198 glutPostRedisplay () ;
202 void keyboard (unsigned char key, int x, int y)
211 if (alpha >= 360.0) alpha -= 360.0;
216 if (alpha < 0.0) alpha += 360.0;
221 if (beta <= -90.0) beta = -90.0;
226 if (beta >= 90.0) beta = 90.0;
230 alpha = 0.0; beta = 0.0;
235 int main(int argc, char** argv)
237 glutInitWindowSize(window_x, window_y);
238 glutInit(&argc, argv);
239 glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
240 glutCreateWindow(argv[0]);
242 glutDisplayFunc(display);
243 glutReshapeFunc(reshape);
244 glutKeyboardFunc(keyboard);