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/gl.h>
35 #define GLFW_INCLUDE_NONE
36 #include <GLFW/glfw3.h>
37
38 /**
39
40 Draw a gear wheel. You'll probably want to call this function when
41 building a display list since we do a lot of trig here.
42
43 Input: inner_radius - radius of hole at center
44 outer_radius - radius at center of teeth
45 width - width of gear teeth - number of teeth
46 tooth_depth - depth of tooth
47
48 **/
49
50 static void
gear(GLfloat inner_radius,GLfloat outer_radius,GLfloat width,GLint teeth,GLfloat tooth_depth)51 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
52 GLint teeth, GLfloat tooth_depth)
53 {
54 GLint i;
55 GLfloat r0, r1, r2;
56 GLfloat angle, da;
57 GLfloat u, v, len;
58
59 r0 = inner_radius;
60 r1 = outer_radius - tooth_depth / 2.f;
61 r2 = outer_radius + tooth_depth / 2.f;
62
63 da = 2.f * (float) M_PI / teeth / 4.f;
64
65 glShadeModel(GL_FLAT);
66
67 glNormal3f(0.f, 0.f, 1.f);
68
69 /* draw front face */
70 glBegin(GL_QUAD_STRIP);
71 for (i = 0; i <= teeth; i++) {
72 angle = i * 2.f * (float) M_PI / teeth;
73 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
74 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
75 if (i < teeth) {
76 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
77 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
78 }
79 }
80 glEnd();
81
82 /* draw front sides of teeth */
83 glBegin(GL_QUADS);
84 da = 2.f * (float) M_PI / teeth / 4.f;
85 for (i = 0; i < teeth; i++) {
86 angle = i * 2.f * (float) M_PI / teeth;
87
88 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
89 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), width * 0.5f);
90 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), width * 0.5f);
91 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
92 }
93 glEnd();
94
95 glNormal3f(0.0, 0.0, -1.0);
96
97 /* draw back face */
98 glBegin(GL_QUAD_STRIP);
99 for (i = 0; i <= teeth; i++) {
100 angle = i * 2.f * (float) M_PI / teeth;
101 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
102 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
103 if (i < teeth) {
104 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
105 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
106 }
107 }
108 glEnd();
109
110 /* draw back sides of teeth */
111 glBegin(GL_QUADS);
112 da = 2.f * (float) M_PI / teeth / 4.f;
113 for (i = 0; i < teeth; i++) {
114 angle = i * 2.f * (float) M_PI / teeth;
115
116 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
117 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), -width * 0.5f);
118 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), -width * 0.5f);
119 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
120 }
121 glEnd();
122
123 /* draw outward faces of teeth */
124 glBegin(GL_QUAD_STRIP);
125 for (i = 0; i < teeth; i++) {
126 angle = i * 2.f * (float) M_PI / teeth;
127
128 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
129 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
130 u = r2 * (float) cos(angle + da) - r1 * (float) cos(angle);
131 v = r2 * (float) sin(angle + da) - r1 * (float) sin(angle);
132 len = (float) sqrt(u * u + v * v);
133 u /= len;
134 v /= len;
135 glNormal3f(v, -u, 0.0);
136 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), width * 0.5f);
137 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), -width * 0.5f);
138 glNormal3f((float) cos(angle), (float) sin(angle), 0.f);
139 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), width * 0.5f);
140 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), -width * 0.5f);
141 u = r1 * (float) cos(angle + 3 * da) - r2 * (float) cos(angle + 2 * da);
142 v = r1 * (float) sin(angle + 3 * da) - r2 * (float) sin(angle + 2 * da);
143 glNormal3f(v, -u, 0.f);
144 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
145 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
146 glNormal3f((float) cos(angle), (float) sin(angle), 0.f);
147 }
148
149 glVertex3f(r1 * (float) cos(0), r1 * (float) sin(0), width * 0.5f);
150 glVertex3f(r1 * (float) cos(0), r1 * (float) sin(0), -width * 0.5f);
151
152 glEnd();
153
154 glShadeModel(GL_SMOOTH);
155
156 /* draw inside radius cylinder */
157 glBegin(GL_QUAD_STRIP);
158 for (i = 0; i <= teeth; i++) {
159 angle = i * 2.f * (float) M_PI / teeth;
160 glNormal3f(-(float) cos(angle), -(float) sin(angle), 0.f);
161 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
162 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
163 }
164 glEnd();
165
166 }
167
168
169 static GLfloat view_rotx = 20.f, view_roty = 30.f, view_rotz = 0.f;
170 static GLint gear1, gear2, gear3;
171 static GLfloat angle = 0.f;
172
173 /* OpenGL draw function & timing */
draw(void)174 static void draw(void)
175 {
176 glClearColor(0.0, 0.0, 0.0, 0.0);
177 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
178
179 glPushMatrix();
180 glRotatef(view_rotx, 1.0, 0.0, 0.0);
181 glRotatef(view_roty, 0.0, 1.0, 0.0);
182 glRotatef(view_rotz, 0.0, 0.0, 1.0);
183
184 glPushMatrix();
185 glTranslatef(-3.0, -2.0, 0.0);
186 glRotatef(angle, 0.0, 0.0, 1.0);
187 glCallList(gear1);
188 glPopMatrix();
189
190 glPushMatrix();
191 glTranslatef(3.1f, -2.f, 0.f);
192 glRotatef(-2.f * angle - 9.f, 0.f, 0.f, 1.f);
193 glCallList(gear2);
194 glPopMatrix();
195
196 glPushMatrix();
197 glTranslatef(-3.1f, 4.2f, 0.f);
198 glRotatef(-2.f * angle - 25.f, 0.f, 0.f, 1.f);
199 glCallList(gear3);
200 glPopMatrix();
201
202 glPopMatrix();
203 }
204
205
206 /* update animation parameters */
animate(void)207 static void animate(void)
208 {
209 angle = 100.f * (float) glfwGetTime();
210 }
211
212
213 /* change view angle, exit upon ESC */
key(GLFWwindow * window,int k,int s,int action,int mods)214 void key( GLFWwindow* window, int k, int s, int action, int mods )
215 {
216 if( action != GLFW_PRESS ) return;
217
218 switch (k) {
219 case GLFW_KEY_Z:
220 if( mods & GLFW_MOD_SHIFT )
221 view_rotz -= 5.0;
222 else
223 view_rotz += 5.0;
224 break;
225 case GLFW_KEY_ESCAPE:
226 glfwSetWindowShouldClose(window, GLFW_TRUE);
227 break;
228 case GLFW_KEY_UP:
229 view_rotx += 5.0;
230 break;
231 case GLFW_KEY_DOWN:
232 view_rotx -= 5.0;
233 break;
234 case GLFW_KEY_LEFT:
235 view_roty += 5.0;
236 break;
237 case GLFW_KEY_RIGHT:
238 view_roty -= 5.0;
239 break;
240 default:
241 return;
242 }
243 }
244
245
246 /* new window size */
reshape(GLFWwindow * window,int width,int height)247 void reshape( GLFWwindow* window, int width, int height )
248 {
249 GLfloat h = (GLfloat) height / (GLfloat) width;
250 GLfloat xmax, znear, zfar;
251
252 znear = 5.0f;
253 zfar = 30.0f;
254 xmax = znear * 0.5f;
255
256 glViewport( 0, 0, (GLint) width, (GLint) height );
257 glMatrixMode( GL_PROJECTION );
258 glLoadIdentity();
259 glFrustum( -xmax, xmax, -xmax*h, xmax*h, znear, zfar );
260 glMatrixMode( GL_MODELVIEW );
261 glLoadIdentity();
262 glTranslatef( 0.0, 0.0, -20.0 );
263 }
264
265
266 /* program & OpenGL initialization */
init(void)267 static void init(void)
268 {
269 static GLfloat pos[4] = {5.f, 5.f, 10.f, 0.f};
270 static GLfloat red[4] = {0.8f, 0.1f, 0.f, 1.f};
271 static GLfloat green[4] = {0.f, 0.8f, 0.2f, 1.f};
272 static GLfloat blue[4] = {0.2f, 0.2f, 1.f, 1.f};
273
274 glLightfv(GL_LIGHT0, GL_POSITION, pos);
275 glEnable(GL_CULL_FACE);
276 glEnable(GL_LIGHTING);
277 glEnable(GL_LIGHT0);
278 glEnable(GL_DEPTH_TEST);
279
280 /* make the gears */
281 gear1 = glGenLists(1);
282 glNewList(gear1, GL_COMPILE);
283 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
284 gear(1.f, 4.f, 1.f, 20, 0.7f);
285 glEndList();
286
287 gear2 = glGenLists(1);
288 glNewList(gear2, GL_COMPILE);
289 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
290 gear(0.5f, 2.f, 2.f, 10, 0.7f);
291 glEndList();
292
293 gear3 = glGenLists(1);
294 glNewList(gear3, GL_COMPILE);
295 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
296 gear(1.3f, 2.f, 0.5f, 10, 0.7f);
297 glEndList();
298
299 glEnable(GL_NORMALIZE);
300 }
301
302
303 /* program entry */
main(int argc,char * argv[])304 int main(int argc, char *argv[])
305 {
306 GLFWwindow* window;
307 int width, height;
308
309 if( !glfwInit() )
310 {
311 fprintf( stderr, "Failed to initialize GLFW\n" );
312 exit( EXIT_FAILURE );
313 }
314
315 glfwWindowHint(GLFW_DEPTH_BITS, 16);
316 glfwWindowHint(GLFW_TRANSPARENT_FRAMEBUFFER, GLFW_TRUE);
317
318 window = glfwCreateWindow( 300, 300, "Gears", NULL, NULL );
319 if (!window)
320 {
321 fprintf( stderr, "Failed to open GLFW window\n" );
322 glfwTerminate();
323 exit( EXIT_FAILURE );
324 }
325
326 // Set callback functions
327 glfwSetFramebufferSizeCallback(window, reshape);
328 glfwSetKeyCallback(window, key);
329
330 glfwMakeContextCurrent(window);
331 gladLoadGL(glfwGetProcAddress);
332 glfwSwapInterval( 1 );
333
334 glfwGetFramebufferSize(window, &width, &height);
335 reshape(window, width, height);
336
337 // Parse command-line options
338 init();
339
340 // Main loop
341 while( !glfwWindowShouldClose(window) )
342 {
343 // Draw gears
344 draw();
345
346 // Update animation
347 animate();
348
349 // Swap buffers
350 glfwSwapBuffers(window);
351 glfwPollEvents();
352 }
353
354 // Terminate GLFW
355 glfwTerminate();
356
357 // Exit program
358 exit( EXIT_SUCCESS );
359 }
360
361