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 Berglund:
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 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
176
177 glPushMatrix();
178 glRotatef(view_rotx, 1.0, 0.0, 0.0);
179 glRotatef(view_roty, 0.0, 1.0, 0.0);
180 glRotatef(view_rotz, 0.0, 0.0, 1.0);
181
182 glPushMatrix();
183 glTranslatef(-3.0, -2.0, 0.0);
184 glRotatef(angle, 0.0, 0.0, 1.0);
185 glCallList(gear1);
186 glPopMatrix();
187
188 glPushMatrix();
189 glTranslatef(3.1f, -2.f, 0.f);
190 glRotatef(-2.f * angle - 9.f, 0.f, 0.f, 1.f);
191 glCallList(gear2);
192 glPopMatrix();
193
194 glPushMatrix();
195 glTranslatef(-3.1f, 4.2f, 0.f);
196 glRotatef(-2.f * angle - 25.f, 0.f, 0.f, 1.f);
197 glCallList(gear3);
198 glPopMatrix();
199
200 glPopMatrix();
201 }
202
203
204 /* update animation parameters */
animate(void)205 static void animate(void)
206 {
207 angle = 100.f * (float) glfwGetTime();
208 }
209
210
211 /* change view angle, exit upon ESC */
key(GLFWwindow * window,int k,int s,int action,int mods)212 void key( GLFWwindow* window, int k, int s, int action, int mods )
213 {
214 if( action != GLFW_PRESS ) return;
215
216 switch (k) {
217 case GLFW_KEY_Z:
218 if( mods & GLFW_MOD_SHIFT )
219 view_rotz -= 5.0;
220 else
221 view_rotz += 5.0;
222 break;
223 case GLFW_KEY_ESCAPE:
224 glfwSetWindowShouldClose(window, GLFW_TRUE);
225 break;
226 case GLFW_KEY_UP:
227 view_rotx += 5.0;
228 break;
229 case GLFW_KEY_DOWN:
230 view_rotx -= 5.0;
231 break;
232 case GLFW_KEY_LEFT:
233 view_roty += 5.0;
234 break;
235 case GLFW_KEY_RIGHT:
236 view_roty -= 5.0;
237 break;
238 default:
239 return;
240 }
241 }
242
243
244 /* new window size */
reshape(GLFWwindow * window,int width,int height)245 void reshape( GLFWwindow* window, int width, int height )
246 {
247 GLfloat h = (GLfloat) height / (GLfloat) width;
248 GLfloat xmax, znear, zfar;
249
250 znear = 5.0f;
251 zfar = 30.0f;
252 xmax = znear * 0.5f;
253
254 glViewport( 0, 0, (GLint) width, (GLint) height );
255 glMatrixMode( GL_PROJECTION );
256 glLoadIdentity();
257 glFrustum( -xmax, xmax, -xmax*h, xmax*h, znear, zfar );
258 glMatrixMode( GL_MODELVIEW );
259 glLoadIdentity();
260 glTranslatef( 0.0, 0.0, -20.0 );
261 }
262
263
264 /* program & OpenGL initialization */
init(void)265 static void init(void)
266 {
267 static GLfloat pos[4] = {5.f, 5.f, 10.f, 0.f};
268 static GLfloat red[4] = {0.8f, 0.1f, 0.f, 1.f};
269 static GLfloat green[4] = {0.f, 0.8f, 0.2f, 1.f};
270 static GLfloat blue[4] = {0.2f, 0.2f, 1.f, 1.f};
271
272 glLightfv(GL_LIGHT0, GL_POSITION, pos);
273 glEnable(GL_CULL_FACE);
274 glEnable(GL_LIGHTING);
275 glEnable(GL_LIGHT0);
276 glEnable(GL_DEPTH_TEST);
277
278 /* make the gears */
279 gear1 = glGenLists(1);
280 glNewList(gear1, GL_COMPILE);
281 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
282 gear(1.f, 4.f, 1.f, 20, 0.7f);
283 glEndList();
284
285 gear2 = glGenLists(1);
286 glNewList(gear2, GL_COMPILE);
287 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
288 gear(0.5f, 2.f, 2.f, 10, 0.7f);
289 glEndList();
290
291 gear3 = glGenLists(1);
292 glNewList(gear3, GL_COMPILE);
293 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
294 gear(1.3f, 2.f, 0.5f, 10, 0.7f);
295 glEndList();
296
297 glEnable(GL_NORMALIZE);
298 }
299
300
301 /* program entry */
main(int argc,char * argv[])302 int main(int argc, char *argv[])
303 {
304 GLFWwindow* window;
305 int width, height;
306
307 if( !glfwInit() )
308 {
309 fprintf( stderr, "Failed to initialize GLFW\n" );
310 exit( EXIT_FAILURE );
311 }
312
313 glfwWindowHint(GLFW_DEPTH_BITS, 16);
314
315 window = glfwCreateWindow( 300, 300, "Gears", NULL, NULL );
316 if (!window)
317 {
318 fprintf( stderr, "Failed to open GLFW window\n" );
319 glfwTerminate();
320 exit( EXIT_FAILURE );
321 }
322
323 // Set callback functions
324 glfwSetFramebufferSizeCallback(window, reshape);
325 glfwSetKeyCallback(window, key);
326
327 glfwMakeContextCurrent(window);
328 gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);
329 glfwSwapInterval( 1 );
330
331 glfwGetFramebufferSize(window, &width, &height);
332 reshape(window, width, height);
333
334 // Parse command-line options
335 init();
336
337 // Main loop
338 while( !glfwWindowShouldClose(window) )
339 {
340 // Draw gears
341 draw();
342
343 // Update animation
344 animate();
345
346 // Swap buffers
347 glfwSwapBuffers(window);
348 glfwPollEvents();
349 }
350
351 // Terminate GLFW
352 glfwTerminate();
353
354 // Exit program
355 exit( EXIT_SUCCESS );
356 }
357
358