1 /*
2 * 3-D gear wheels. This program is in the public domain.
3 *
4 * Command line options:
5 * -info print GL implementation information
6 * -exit automatically exit after 30 seconds
7 *
8 *
9 * Brian Paul
10 *
11 *
12 * Marcus Geelnard:
13 * - Conversion to GLFW
14 * - Time based rendering (frame rate independent)
15 * - Slightly modified camera that should work better for stereo viewing
16 *
17 *
18 * Camilla Löwy:
19 * - Removed FPS counter (this is not a benchmark)
20 * - Added a few comments
21 * - Enabled vsync
22 */
23
24 #if defined(_MSC_VER)
25 // Make MS math.h define M_PI
26 #define _USE_MATH_DEFINES
27 #endif
28
29 #include <math.h>
30 #include <stdlib.h>
31 #include <stdio.h>
32 #include <string.h>
33
34 #include <glad/glad.h>
35 #include <GLFW/glfw3.h>
36
37 /**
38
39 Draw a gear wheel. You'll probably want to call this function when
40 building a display list since we do a lot of trig here.
41
42 Input: inner_radius - radius of hole at center
43 outer_radius - radius at center of teeth
44 width - width of gear teeth - number of teeth
45 tooth_depth - depth of tooth
46
47 **/
48
49 static void
gear(GLfloat inner_radius,GLfloat outer_radius,GLfloat width,GLint teeth,GLfloat tooth_depth)50 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
51 GLint teeth, GLfloat tooth_depth)
52 {
53 GLint i;
54 GLfloat r0, r1, r2;
55 GLfloat angle, da;
56 GLfloat u, v, len;
57
58 r0 = inner_radius;
59 r1 = outer_radius - tooth_depth / 2.f;
60 r2 = outer_radius + tooth_depth / 2.f;
61
62 da = 2.f * (float) M_PI / teeth / 4.f;
63
64 glShadeModel(GL_FLAT);
65
66 glNormal3f(0.f, 0.f, 1.f);
67
68 /* draw front face */
69 glBegin(GL_QUAD_STRIP);
70 for (i = 0; i <= teeth; i++) {
71 angle = i * 2.f * (float) M_PI / teeth;
72 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
73 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
74 if (i < teeth) {
75 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
76 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
77 }
78 }
79 glEnd();
80
81 /* draw front sides of teeth */
82 glBegin(GL_QUADS);
83 da = 2.f * (float) M_PI / teeth / 4.f;
84 for (i = 0; i < teeth; i++) {
85 angle = i * 2.f * (float) M_PI / teeth;
86
87 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
88 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), width * 0.5f);
89 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), width * 0.5f);
90 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
91 }
92 glEnd();
93
94 glNormal3f(0.0, 0.0, -1.0);
95
96 /* draw back face */
97 glBegin(GL_QUAD_STRIP);
98 for (i = 0; i <= teeth; i++) {
99 angle = i * 2.f * (float) M_PI / teeth;
100 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
101 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
102 if (i < teeth) {
103 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
104 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
105 }
106 }
107 glEnd();
108
109 /* draw back sides of teeth */
110 glBegin(GL_QUADS);
111 da = 2.f * (float) M_PI / teeth / 4.f;
112 for (i = 0; i < teeth; i++) {
113 angle = i * 2.f * (float) M_PI / teeth;
114
115 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
116 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), -width * 0.5f);
117 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), -width * 0.5f);
118 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
119 }
120 glEnd();
121
122 /* draw outward faces of teeth */
123 glBegin(GL_QUAD_STRIP);
124 for (i = 0; i < teeth; i++) {
125 angle = i * 2.f * (float) M_PI / teeth;
126
127 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
128 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
129 u = r2 * (float) cos(angle + da) - r1 * (float) cos(angle);
130 v = r2 * (float) sin(angle + da) - r1 * (float) sin(angle);
131 len = (float) sqrt(u * u + v * v);
132 u /= len;
133 v /= len;
134 glNormal3f(v, -u, 0.0);
135 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), width * 0.5f);
136 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), -width * 0.5f);
137 glNormal3f((float) cos(angle), (float) sin(angle), 0.f);
138 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), width * 0.5f);
139 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), -width * 0.5f);
140 u = r1 * (float) cos(angle + 3 * da) - r2 * (float) cos(angle + 2 * da);
141 v = r1 * (float) sin(angle + 3 * da) - r2 * (float) sin(angle + 2 * da);
142 glNormal3f(v, -u, 0.f);
143 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
144 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
145 glNormal3f((float) cos(angle), (float) sin(angle), 0.f);
146 }
147
148 glVertex3f(r1 * (float) cos(0), r1 * (float) sin(0), width * 0.5f);
149 glVertex3f(r1 * (float) cos(0), r1 * (float) sin(0), -width * 0.5f);
150
151 glEnd();
152
153 glShadeModel(GL_SMOOTH);
154
155 /* draw inside radius cylinder */
156 glBegin(GL_QUAD_STRIP);
157 for (i = 0; i <= teeth; i++) {
158 angle = i * 2.f * (float) M_PI / teeth;
159 glNormal3f(-(float) cos(angle), -(float) sin(angle), 0.f);
160 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
161 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
162 }
163 glEnd();
164
165 }
166
167
168 static GLfloat view_rotx = 20.f, view_roty = 30.f, view_rotz = 0.f;
169 static GLint gear1, gear2, gear3;
170 static GLfloat angle = 0.f;
171
172 /* OpenGL draw function & timing */
draw(void)173 static void draw(void)
174 {
175 glClearColor(0.0, 0.0, 0.0, 0.0);
176 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
177
178 glPushMatrix();
179 glRotatef(view_rotx, 1.0, 0.0, 0.0);
180 glRotatef(view_roty, 0.0, 1.0, 0.0);
181 glRotatef(view_rotz, 0.0, 0.0, 1.0);
182
183 glPushMatrix();
184 glTranslatef(-3.0, -2.0, 0.0);
185 glRotatef(angle, 0.0, 0.0, 1.0);
186 glCallList(gear1);
187 glPopMatrix();
188
189 glPushMatrix();
190 glTranslatef(3.1f, -2.f, 0.f);
191 glRotatef(-2.f * angle - 9.f, 0.f, 0.f, 1.f);
192 glCallList(gear2);
193 glPopMatrix();
194
195 glPushMatrix();
196 glTranslatef(-3.1f, 4.2f, 0.f);
197 glRotatef(-2.f * angle - 25.f, 0.f, 0.f, 1.f);
198 glCallList(gear3);
199 glPopMatrix();
200
201 glPopMatrix();
202 }
203
204
205 /* update animation parameters */
animate(void)206 static void animate(void)
207 {
208 angle = 100.f * (float) glfwGetTime();
209 }
210
211
212 /* change view angle, exit upon ESC */
key(GLFWwindow * window,int k,int s,int action,int mods)213 void key( GLFWwindow* window, int k, int s, int action, int mods )
214 {
215 if( action != GLFW_PRESS ) return;
216
217 switch (k) {
218 case GLFW_KEY_Z:
219 if( mods & GLFW_MOD_SHIFT )
220 view_rotz -= 5.0;
221 else
222 view_rotz += 5.0;
223 break;
224 case GLFW_KEY_ESCAPE:
225 glfwSetWindowShouldClose(window, GLFW_TRUE);
226 break;
227 case GLFW_KEY_UP:
228 view_rotx += 5.0;
229 break;
230 case GLFW_KEY_DOWN:
231 view_rotx -= 5.0;
232 break;
233 case GLFW_KEY_LEFT:
234 view_roty += 5.0;
235 break;
236 case GLFW_KEY_RIGHT:
237 view_roty -= 5.0;
238 break;
239 default:
240 return;
241 }
242 }
243
244
245 /* new window size */
reshape(GLFWwindow * window,int width,int height)246 void reshape( GLFWwindow* window, int width, int height )
247 {
248 GLfloat h = (GLfloat) height / (GLfloat) width;
249 GLfloat xmax, znear, zfar;
250
251 znear = 5.0f;
252 zfar = 30.0f;
253 xmax = znear * 0.5f;
254
255 glViewport( 0, 0, (GLint) width, (GLint) height );
256 glMatrixMode( GL_PROJECTION );
257 glLoadIdentity();
258 glFrustum( -xmax, xmax, -xmax*h, xmax*h, znear, zfar );
259 glMatrixMode( GL_MODELVIEW );
260 glLoadIdentity();
261 glTranslatef( 0.0, 0.0, -20.0 );
262 }
263
264
265 /* program & OpenGL initialization */
init(void)266 static void init(void)
267 {
268 static GLfloat pos[4] = {5.f, 5.f, 10.f, 0.f};
269 static GLfloat red[4] = {0.8f, 0.1f, 0.f, 1.f};
270 static GLfloat green[4] = {0.f, 0.8f, 0.2f, 1.f};
271 static GLfloat blue[4] = {0.2f, 0.2f, 1.f, 1.f};
272
273 glLightfv(GL_LIGHT0, GL_POSITION, pos);
274 glEnable(GL_CULL_FACE);
275 glEnable(GL_LIGHTING);
276 glEnable(GL_LIGHT0);
277 glEnable(GL_DEPTH_TEST);
278
279 /* make the gears */
280 gear1 = glGenLists(1);
281 glNewList(gear1, GL_COMPILE);
282 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
283 gear(1.f, 4.f, 1.f, 20, 0.7f);
284 glEndList();
285
286 gear2 = glGenLists(1);
287 glNewList(gear2, GL_COMPILE);
288 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
289 gear(0.5f, 2.f, 2.f, 10, 0.7f);
290 glEndList();
291
292 gear3 = glGenLists(1);
293 glNewList(gear3, GL_COMPILE);
294 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
295 gear(1.3f, 2.f, 0.5f, 10, 0.7f);
296 glEndList();
297
298 glEnable(GL_NORMALIZE);
299 }
300
301
302 /* program entry */
main(int argc,char * argv[])303 int main(int argc, char *argv[])
304 {
305 GLFWwindow* window;
306 int width, height;
307
308 if( !glfwInit() )
309 {
310 fprintf( stderr, "Failed to initialize GLFW\n" );
311 exit( EXIT_FAILURE );
312 }
313
314 glfwWindowHint(GLFW_DEPTH_BITS, 16);
315 glfwWindowHint(GLFW_TRANSPARENT_FRAMEBUFFER, GLFW_TRUE);
316
317 window = glfwCreateWindow( 300, 300, "Gears", NULL, NULL );
318 if (!window)
319 {
320 fprintf( stderr, "Failed to open GLFW window\n" );
321 glfwTerminate();
322 exit( EXIT_FAILURE );
323 }
324
325 // Set callback functions
326 glfwSetFramebufferSizeCallback(window, reshape);
327 glfwSetKeyCallback(window, key);
328
329 glfwMakeContextCurrent(window);
330 gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);
331 glfwSwapInterval( 1 );
332
333 glfwGetFramebufferSize(window, &width, &height);
334 reshape(window, width, height);
335
336 // Parse command-line options
337 init();
338
339 // Main loop
340 while( !glfwWindowShouldClose(window) )
341 {
342 // Draw gears
343 draw();
344
345 // Update animation
346 animate();
347
348 // Swap buffers
349 glfwSwapBuffers(window);
350 glfwPollEvents();
351 }
352
353 // Terminate GLFW
354 glfwTerminate();
355
356 // Exit program
357 exit( EXIT_SUCCESS );
358 }
359
360