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 #define GLAD_GL_IMPLEMENTATION
35 #include <glad/gl.h>
36 #define GLFW_INCLUDE_NONE
37 #include <GLFW/glfw3.h>
38
39 /**
40
41 Draw a gear wheel. You'll probably want to call this function when
42 building a display list since we do a lot of trig here.
43
44 Input: inner_radius - radius of hole at center
45 outer_radius - radius at center of teeth
46 width - width of gear teeth - number of teeth
47 tooth_depth - depth of tooth
48
49 **/
50
51 static void
gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width, GLint teeth, GLfloat tooth_depth)52 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
53 GLint teeth, GLfloat tooth_depth)
54 {
55 GLint i;
56 GLfloat r0, r1, r2;
57 GLfloat angle, da;
58 GLfloat u, v, len;
59
60 r0 = inner_radius;
61 r1 = outer_radius - tooth_depth / 2.f;
62 r2 = outer_radius + tooth_depth / 2.f;
63
64 da = 2.f * (float) M_PI / teeth / 4.f;
65
66 glShadeModel(GL_FLAT);
67
68 glNormal3f(0.f, 0.f, 1.f);
69
70 /* draw front face */
71 glBegin(GL_QUAD_STRIP);
72 for (i = 0; i <= teeth; i++) {
73 angle = i * 2.f * (float) M_PI / teeth;
74 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
75 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
76 if (i < teeth) {
77 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
78 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
79 }
80 }
81 glEnd();
82
83 /* draw front sides of teeth */
84 glBegin(GL_QUADS);
85 da = 2.f * (float) M_PI / teeth / 4.f;
86 for (i = 0; i < teeth; i++) {
87 angle = i * 2.f * (float) M_PI / teeth;
88
89 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
90 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), width * 0.5f);
91 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), width * 0.5f);
92 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
93 }
94 glEnd();
95
96 glNormal3f(0.0, 0.0, -1.0);
97
98 /* draw back face */
99 glBegin(GL_QUAD_STRIP);
100 for (i = 0; i <= teeth; i++) {
101 angle = i * 2.f * (float) M_PI / teeth;
102 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
103 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
104 if (i < teeth) {
105 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
106 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
107 }
108 }
109 glEnd();
110
111 /* draw back sides of teeth */
112 glBegin(GL_QUADS);
113 da = 2.f * (float) M_PI / teeth / 4.f;
114 for (i = 0; i < teeth; i++) {
115 angle = i * 2.f * (float) M_PI / teeth;
116
117 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
118 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), -width * 0.5f);
119 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), -width * 0.5f);
120 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
121 }
122 glEnd();
123
124 /* draw outward faces of teeth */
125 glBegin(GL_QUAD_STRIP);
126 for (i = 0; i < teeth; i++) {
127 angle = i * 2.f * (float) M_PI / teeth;
128
129 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f);
130 glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f);
131 u = r2 * (float) cos(angle + da) - r1 * (float) cos(angle);
132 v = r2 * (float) sin(angle + da) - r1 * (float) sin(angle);
133 len = (float) sqrt(u * u + v * v);
134 u /= len;
135 v /= len;
136 glNormal3f(v, -u, 0.0);
137 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), width * 0.5f);
138 glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), -width * 0.5f);
139 glNormal3f((float) cos(angle), (float) sin(angle), 0.f);
140 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), width * 0.5f);
141 glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), -width * 0.5f);
142 u = r1 * (float) cos(angle + 3 * da) - r2 * (float) cos(angle + 2 * da);
143 v = r1 * (float) sin(angle + 3 * da) - r2 * (float) sin(angle + 2 * da);
144 glNormal3f(v, -u, 0.f);
145 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f);
146 glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f);
147 glNormal3f((float) cos(angle), (float) sin(angle), 0.f);
148 }
149
150 glVertex3f(r1 * (float) cos(0), r1 * (float) sin(0), width * 0.5f);
151 glVertex3f(r1 * (float) cos(0), r1 * (float) sin(0), -width * 0.5f);
152
153 glEnd();
154
155 glShadeModel(GL_SMOOTH);
156
157 /* draw inside radius cylinder */
158 glBegin(GL_QUAD_STRIP);
159 for (i = 0; i <= teeth; i++) {
160 angle = i * 2.f * (float) M_PI / teeth;
161 glNormal3f(-(float) cos(angle), -(float) sin(angle), 0.f);
162 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f);
163 glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f);
164 }
165 glEnd();
166
167 }
168
169
170 static GLfloat view_rotx = 20.f, view_roty = 30.f, view_rotz = 0.f;
171 static GLint gear1, gear2, gear3;
172 static GLfloat angle = 0.f;
173
174 /* OpenGL draw function & timing */
draw(void)175 static void draw(void)
176 {
177 glClearColor(0.0, 0.0, 0.0, 0.0);
178 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
179
180 glPushMatrix();
181 glRotatef(view_rotx, 1.0, 0.0, 0.0);
182 glRotatef(view_roty, 0.0, 1.0, 0.0);
183 glRotatef(view_rotz, 0.0, 0.0, 1.0);
184
185 glPushMatrix();
186 glTranslatef(-3.0, -2.0, 0.0);
187 glRotatef(angle, 0.0, 0.0, 1.0);
188 glCallList(gear1);
189 glPopMatrix();
190
191 glPushMatrix();
192 glTranslatef(3.1f, -2.f, 0.f);
193 glRotatef(-2.f * angle - 9.f, 0.f, 0.f, 1.f);
194 glCallList(gear2);
195 glPopMatrix();
196
197 glPushMatrix();
198 glTranslatef(-3.1f, 4.2f, 0.f);
199 glRotatef(-2.f * angle - 25.f, 0.f, 0.f, 1.f);
200 glCallList(gear3);
201 glPopMatrix();
202
203 glPopMatrix();
204 }
205
206
207 /* update animation parameters */
animate(void)208 static void animate(void)
209 {
210 angle = 100.f * (float) glfwGetTime();
211 }
212
213
214 /* change view angle, exit upon ESC */
key( GLFWwindow* window, int k, int s, int action, int mods )215 void key( GLFWwindow* window, int k, int s, int action, int mods )
216 {
217 if( action != GLFW_PRESS ) return;
218
219 switch (k) {
220 case GLFW_KEY_Z:
221 if( mods & GLFW_MOD_SHIFT )
222 view_rotz -= 5.0;
223 else
224 view_rotz += 5.0;
225 break;
226 case GLFW_KEY_ESCAPE:
227 glfwSetWindowShouldClose(window, GLFW_TRUE);
228 break;
229 case GLFW_KEY_UP:
230 view_rotx += 5.0;
231 break;
232 case GLFW_KEY_DOWN:
233 view_rotx -= 5.0;
234 break;
235 case GLFW_KEY_LEFT:
236 view_roty += 5.0;
237 break;
238 case GLFW_KEY_RIGHT:
239 view_roty -= 5.0;
240 break;
241 default:
242 return;
243 }
244 }
245
246
247 /* new window size */
reshape( GLFWwindow* window, int width, int height )248 void reshape( GLFWwindow* window, int width, int height )
249 {
250 GLfloat h = (GLfloat) height / (GLfloat) width;
251 GLfloat xmax, znear, zfar;
252
253 znear = 5.0f;
254 zfar = 30.0f;
255 xmax = znear * 0.5f;
256
257 glViewport( 0, 0, (GLint) width, (GLint) height );
258 glMatrixMode( GL_PROJECTION );
259 glLoadIdentity();
260 glFrustum( -xmax, xmax, -xmax*h, xmax*h, znear, zfar );
261 glMatrixMode( GL_MODELVIEW );
262 glLoadIdentity();
263 glTranslatef( 0.0, 0.0, -20.0 );
264 }
265
266
267 /* program & OpenGL initialization */
init(void)268 static void init(void)
269 {
270 static GLfloat pos[4] = {5.f, 5.f, 10.f, 0.f};
271 static GLfloat red[4] = {0.8f, 0.1f, 0.f, 1.f};
272 static GLfloat green[4] = {0.f, 0.8f, 0.2f, 1.f};
273 static GLfloat blue[4] = {0.2f, 0.2f, 1.f, 1.f};
274
275 glLightfv(GL_LIGHT0, GL_POSITION, pos);
276 glEnable(GL_CULL_FACE);
277 glEnable(GL_LIGHTING);
278 glEnable(GL_LIGHT0);
279 glEnable(GL_DEPTH_TEST);
280
281 /* make the gears */
282 gear1 = glGenLists(1);
283 glNewList(gear1, GL_COMPILE);
284 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
285 gear(1.f, 4.f, 1.f, 20, 0.7f);
286 glEndList();
287
288 gear2 = glGenLists(1);
289 glNewList(gear2, GL_COMPILE);
290 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
291 gear(0.5f, 2.f, 2.f, 10, 0.7f);
292 glEndList();
293
294 gear3 = glGenLists(1);
295 glNewList(gear3, GL_COMPILE);
296 glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
297 gear(1.3f, 2.f, 0.5f, 10, 0.7f);
298 glEndList();
299
300 glEnable(GL_NORMALIZE);
301 }
302
303
304 /* program entry */
main(int argc, char *argv[])305 int main(int argc, char *argv[])
306 {
307 GLFWwindow* window;
308 int width, height;
309
310 if( !glfwInit() )
311 {
312 fprintf( stderr, "Failed to initialize GLFW\n" );
313 exit( EXIT_FAILURE );
314 }
315
316 glfwWindowHint(GLFW_DEPTH_BITS, 16);
317 glfwWindowHint(GLFW_TRANSPARENT_FRAMEBUFFER, GLFW_TRUE);
318
319 window = glfwCreateWindow( 300, 300, "Gears", NULL, NULL );
320 if (!window)
321 {
322 fprintf( stderr, "Failed to open GLFW window\n" );
323 glfwTerminate();
324 exit( EXIT_FAILURE );
325 }
326
327 // Set callback functions
328 glfwSetFramebufferSizeCallback(window, reshape);
329 glfwSetKeyCallback(window, key);
330
331 glfwMakeContextCurrent(window);
332 gladLoadGL(glfwGetProcAddress);
333 glfwSwapInterval( 1 );
334
335 glfwGetFramebufferSize(window, &width, &height);
336 reshape(window, width, height);
337
338 // Parse command-line options
339 init();
340
341 // Main loop
342 while( !glfwWindowShouldClose(window) )
343 {
344 // Draw gears
345 draw();
346
347 // Update animation
348 animate();
349
350 // Swap buffers
351 glfwSwapBuffers(window);
352 glfwPollEvents();
353 }
354
355 // Terminate GLFW
356 glfwTerminate();
357
358 // Exit program
359 exit( EXIT_SUCCESS );
360 }
361
362