ref: c454f4426dea6fd05b76a56e7990790abd61c01c
dir: /external/glfw/examples/gears.c/
/* * 3-D gear wheels. This program is in the public domain. * * Command line options: * -info print GL implementation information * -exit automatically exit after 30 seconds * * * Brian Paul * * * Marcus Geelnard: * - Conversion to GLFW * - Time based rendering (frame rate independent) * - Slightly modified camera that should work better for stereo viewing * * * Camilla Löwy: * - Removed FPS counter (this is not a benchmark) * - Added a few comments * - Enabled vsync */ #if defined(_MSC_VER) // Make MS math.h define M_PI #define _USE_MATH_DEFINES #endif #include <math.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <glad/gl.h> #define GLFW_INCLUDE_NONE #include <GLFW/glfw3.h> /** Draw a gear wheel. You'll probably want to call this function when building a display list since we do a lot of trig here. Input: inner_radius - radius of hole at center outer_radius - radius at center of teeth width - width of gear teeth - number of teeth tooth_depth - depth of tooth **/ static void gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width, GLint teeth, GLfloat tooth_depth) { GLint i; GLfloat r0, r1, r2; GLfloat angle, da; GLfloat u, v, len; r0 = inner_radius; r1 = outer_radius - tooth_depth / 2.f; r2 = outer_radius + tooth_depth / 2.f; da = 2.f * (float) M_PI / teeth / 4.f; glShadeModel(GL_FLAT); glNormal3f(0.f, 0.f, 1.f); /* draw front face */ glBegin(GL_QUAD_STRIP); for (i = 0; i <= teeth; i++) { angle = i * 2.f * (float) M_PI / teeth; glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f); glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f); if (i < teeth) { glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f); glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f); } } glEnd(); /* draw front sides of teeth */ glBegin(GL_QUADS); da = 2.f * (float) M_PI / teeth / 4.f; for (i = 0; i < teeth; i++) { angle = i * 2.f * (float) M_PI / teeth; glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f); glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), width * 0.5f); glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), width * 0.5f); glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f); } glEnd(); glNormal3f(0.0, 0.0, -1.0); /* draw back face */ glBegin(GL_QUAD_STRIP); for (i = 0; i <= teeth; i++) { angle = i * 2.f * (float) M_PI / teeth; glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f); glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f); if (i < teeth) { glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f); glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f); } } glEnd(); /* draw back sides of teeth */ glBegin(GL_QUADS); da = 2.f * (float) M_PI / teeth / 4.f; for (i = 0; i < teeth; i++) { angle = i * 2.f * (float) M_PI / teeth; glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f); glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), -width * 0.5f); glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), -width * 0.5f); glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f); } glEnd(); /* draw outward faces of teeth */ glBegin(GL_QUAD_STRIP); for (i = 0; i < teeth; i++) { angle = i * 2.f * (float) M_PI / teeth; glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), width * 0.5f); glVertex3f(r1 * (float) cos(angle), r1 * (float) sin(angle), -width * 0.5f); u = r2 * (float) cos(angle + da) - r1 * (float) cos(angle); v = r2 * (float) sin(angle + da) - r1 * (float) sin(angle); len = (float) sqrt(u * u + v * v); u /= len; v /= len; glNormal3f(v, -u, 0.0); glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), width * 0.5f); glVertex3f(r2 * (float) cos(angle + da), r2 * (float) sin(angle + da), -width * 0.5f); glNormal3f((float) cos(angle), (float) sin(angle), 0.f); glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), width * 0.5f); glVertex3f(r2 * (float) cos(angle + 2 * da), r2 * (float) sin(angle + 2 * da), -width * 0.5f); u = r1 * (float) cos(angle + 3 * da) - r2 * (float) cos(angle + 2 * da); v = r1 * (float) sin(angle + 3 * da) - r2 * (float) sin(angle + 2 * da); glNormal3f(v, -u, 0.f); glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), width * 0.5f); glVertex3f(r1 * (float) cos(angle + 3 * da), r1 * (float) sin(angle + 3 * da), -width * 0.5f); glNormal3f((float) cos(angle), (float) sin(angle), 0.f); } glVertex3f(r1 * (float) cos(0), r1 * (float) sin(0), width * 0.5f); glVertex3f(r1 * (float) cos(0), r1 * (float) sin(0), -width * 0.5f); glEnd(); glShadeModel(GL_SMOOTH); /* draw inside radius cylinder */ glBegin(GL_QUAD_STRIP); for (i = 0; i <= teeth; i++) { angle = i * 2.f * (float) M_PI / teeth; glNormal3f(-(float) cos(angle), -(float) sin(angle), 0.f); glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), -width * 0.5f); glVertex3f(r0 * (float) cos(angle), r0 * (float) sin(angle), width * 0.5f); } glEnd(); } static GLfloat view_rotx = 20.f, view_roty = 30.f, view_rotz = 0.f; static GLint gear1, gear2, gear3; static GLfloat angle = 0.f; /* OpenGL draw function & timing */ static void draw(void) { glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glPushMatrix(); glRotatef(view_rotx, 1.0, 0.0, 0.0); glRotatef(view_roty, 0.0, 1.0, 0.0); glRotatef(view_rotz, 0.0, 0.0, 1.0); glPushMatrix(); glTranslatef(-3.0, -2.0, 0.0); glRotatef(angle, 0.0, 0.0, 1.0); glCallList(gear1); glPopMatrix(); glPushMatrix(); glTranslatef(3.1f, -2.f, 0.f); glRotatef(-2.f * angle - 9.f, 0.f, 0.f, 1.f); glCallList(gear2); glPopMatrix(); glPushMatrix(); glTranslatef(-3.1f, 4.2f, 0.f); glRotatef(-2.f * angle - 25.f, 0.f, 0.f, 1.f); glCallList(gear3); glPopMatrix(); glPopMatrix(); } /* update animation parameters */ static void animate(void) { angle = 100.f * (float) glfwGetTime(); } /* change view angle, exit upon ESC */ void key( GLFWwindow* window, int k, int s, int action, int mods ) { if( action != GLFW_PRESS ) return; switch (k) { case GLFW_KEY_Z: if( mods & GLFW_MOD_SHIFT ) view_rotz -= 5.0; else view_rotz += 5.0; break; case GLFW_KEY_ESCAPE: glfwSetWindowShouldClose(window, GLFW_TRUE); break; case GLFW_KEY_UP: view_rotx += 5.0; break; case GLFW_KEY_DOWN: view_rotx -= 5.0; break; case GLFW_KEY_LEFT: view_roty += 5.0; break; case GLFW_KEY_RIGHT: view_roty -= 5.0; break; default: return; } } /* new window size */ void reshape( GLFWwindow* window, int width, int height ) { GLfloat h = (GLfloat) height / (GLfloat) width; GLfloat xmax, znear, zfar; znear = 5.0f; zfar = 30.0f; xmax = znear * 0.5f; glViewport( 0, 0, (GLint) width, (GLint) height ); glMatrixMode( GL_PROJECTION ); glLoadIdentity(); glFrustum( -xmax, xmax, -xmax*h, xmax*h, znear, zfar ); glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); glTranslatef( 0.0, 0.0, -20.0 ); } /* program & OpenGL initialization */ static void init(void) { static GLfloat pos[4] = {5.f, 5.f, 10.f, 0.f}; static GLfloat red[4] = {0.8f, 0.1f, 0.f, 1.f}; static GLfloat green[4] = {0.f, 0.8f, 0.2f, 1.f}; static GLfloat blue[4] = {0.2f, 0.2f, 1.f, 1.f}; glLightfv(GL_LIGHT0, GL_POSITION, pos); glEnable(GL_CULL_FACE); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_DEPTH_TEST); /* make the gears */ gear1 = glGenLists(1); glNewList(gear1, GL_COMPILE); glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red); gear(1.f, 4.f, 1.f, 20, 0.7f); glEndList(); gear2 = glGenLists(1); glNewList(gear2, GL_COMPILE); glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green); gear(0.5f, 2.f, 2.f, 10, 0.7f); glEndList(); gear3 = glGenLists(1); glNewList(gear3, GL_COMPILE); glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue); gear(1.3f, 2.f, 0.5f, 10, 0.7f); glEndList(); glEnable(GL_NORMALIZE); } /* program entry */ int main(int argc, char *argv[]) { GLFWwindow* window; int width, height; if( !glfwInit() ) { fprintf( stderr, "Failed to initialize GLFW\n" ); exit( EXIT_FAILURE ); } glfwWindowHint(GLFW_DEPTH_BITS, 16); glfwWindowHint(GLFW_TRANSPARENT_FRAMEBUFFER, GLFW_TRUE); window = glfwCreateWindow( 300, 300, "Gears", NULL, NULL ); if (!window) { fprintf( stderr, "Failed to open GLFW window\n" ); glfwTerminate(); exit( EXIT_FAILURE ); } // Set callback functions glfwSetFramebufferSizeCallback(window, reshape); glfwSetKeyCallback(window, key); glfwMakeContextCurrent(window); gladLoadGL(glfwGetProcAddress); glfwSwapInterval( 1 ); glfwGetFramebufferSize(window, &width, &height); reshape(window, width, height); // Parse command-line options init(); // Main loop while( !glfwWindowShouldClose(window) ) { // Draw gears draw(); // Update animation animate(); // Swap buffers glfwSwapBuffers(window); glfwPollEvents(); } // Terminate GLFW glfwTerminate(); // Exit program exit( EXIT_SUCCESS ); }