ref: ab82f014aea39a8b12df8ad8759933664308c17c
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 );
}