RedBear-OS/recipes/demos/gears/gears.c

/* gears.c */

/*
 * 3-D gear wheels.  This program is in the public domain.
 *
 * Brian Paul
 */

/* Conversion to GLUT by Mark J. Kilgard */

#include <math.h>
#include <stdlib.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/osmesa.h>
#include <orbital.h>
#include <stdio.h>

#ifndef M_PI
#define M_PI 3.14159265
#endif

/**

  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 / 2.0;
  r2 = outer_radius + tooth_depth / 2.0;

  da = 2.0 * M_PI / teeth / 4.0;

  glShadeModel(GL_FLAT);

  glNormal3f(0.0, 0.0, 1.0);

  /* draw front face */
  glBegin(GL_QUAD_STRIP);
  for (i = 0; i <= teeth; i++) {
    angle = i * 2.0 * M_PI / teeth;
    glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
    glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
    glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
    glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  }
  glEnd();

  /* draw front sides of teeth */
  glBegin(GL_QUADS);
  da = 2.0 * M_PI / teeth / 4.0;
  for (i = 0; i < teeth; i++) {
    angle = i * 2.0 * M_PI / teeth;

    glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
    glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
    glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
    glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  }
  glEnd();

  glNormal3f(0.0, 0.0, -1.0);

  /* draw back face */
  glBegin(GL_QUAD_STRIP);
  for (i = 0; i <= teeth; i++) {
    angle = i * 2.0 * M_PI / teeth;
    glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
    glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
    glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
    glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
  }
  glEnd();

  /* draw back sides of teeth */
  glBegin(GL_QUADS);
  da = 2.0 * M_PI / teeth / 4.0;
  for (i = 0; i < teeth; i++) {
    angle = i * 2.0 * M_PI / teeth;

    glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
    glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
    glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
    glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
  }
  glEnd();

  /* draw outward faces of teeth */
  glBegin(GL_QUAD_STRIP);
  for (i = 0; i < teeth; i++) {
    angle = i * 2.0 * M_PI / teeth;

    glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
    glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
    u = r2 * cos(angle + da) - r1 * cos(angle);
    v = r2 * sin(angle + da) - r1 * sin(angle);
    len = sqrt(u * u + v * v);
    u /= len;
    v /= len;
    glNormal3f(v, -u, 0.0);
    glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
    glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
    glNormal3f(cos(angle), sin(angle), 0.0);
    glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
    glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
    u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
    v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
    glNormal3f(v, -u, 0.0);
    glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
    glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
    glNormal3f(cos(angle), sin(angle), 0.0);
  }

  glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
  glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);

  glEnd();

  glShadeModel(GL_SMOOTH);

  /* draw inside radius cylinder */
  glBegin(GL_QUAD_STRIP);
  for (i = 0; i <= teeth; i++) {
    angle = i * 2.0 * M_PI / teeth;

    glNormal3f(-cos(angle), -sin(angle), 0.0);
    glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
    glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  }
  glEnd();

}

static int width = 800;
static int height = 600;

static void * buffer = NULL;
static void * window = NULL;

static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
static GLint gear1, gear2, gear3;
static GLfloat angle = 0.0;

static GLuint limit;
static GLuint count = 1;

static void
sync(void)
{
  glFinish();

  uint32_t * frame_data = orb_window_data(window);
  uint32_t * image_data = (uint32_t *)buffer;

  int i;
  for(i = 0; i < width * height; i++) {
    frame_data[i] = image_data[i] | 0xFF000000;
  }

  orb_window_sync(window);
}

static void
draw(void)
{
  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(3.1, -2.0, 0.0);
  glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
  glCallList(gear2);
  glPopMatrix();

  glPushMatrix();
  glTranslatef(-3.1, 4.2, 0.0);
  glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
  glCallList(gear3);
  glPopMatrix();

  glPopMatrix();

  sync();

  count++;
  if (count == limit) {
    exit(0);
  }
}

static void
idle(void)
{
  angle += 2.0;
  draw();
}

/* new window size or exposure */
static void
reshape(int width, int height)
{
  GLfloat h = (GLfloat) height / (GLfloat) width;

  glViewport(0, 0, (GLint) width, (GLint) height);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glTranslatef(0.0, 0.0, -40.0);
}

static void
init(void)
{
  static GLfloat pos[4] =
  {5.0, 5.0, 10.0, 0.0};
  static GLfloat red[4] =
  {0.8, 0.1, 0.0, 1.0};
  static GLfloat green[4] =
  {0.0, 0.8, 0.2, 1.0};
  static GLfloat blue[4] =
  {0.2, 0.2, 1.0, 1.0};

  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(1.0, 4.0, 1.0, 20, 0.7);
  glEndList();

  gear2 = glGenLists(1);
  glNewList(gear2, GL_COMPILE);
  glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
  gear(0.5, 2.0, 2.0, 10, 0.7);
  glEndList();

  gear3 = glGenLists(1);
  glNewList(gear3, GL_COMPILE);
  glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
  gear(1.3, 2.0, 0.5, 10, 0.7);
  glEndList();

  glEnable(GL_NORMALIZE);
}

main(int argc, char *argv[])
{
  if (argc > 1) {
    /* do 'n' frames then exit */
    limit = atoi(argv[1]) + 1;
  } else {
    limit = 0;
  }

  OSMesaContext ctx = OSMesaCreateContextExt(OSMESA_BGRA, 16, 0, 0, NULL);
  if (!ctx) {
    printf("OSMesaCreateContextExt failed\n");
    return 1;
  }

  buffer = malloc(width * height * 4);
  if(!buffer) {
    printf("malloc failed\n");
    OSMesaDestroyContext(ctx);
    return 1;
  }

  if (!OSMesaMakeCurrent(ctx, buffer, GL_UNSIGNED_BYTE, width, height)) {
    printf("OSMesaMakeCurrent failed\n");
    OSMesaDestroyContext(ctx);
    return 1;
  }

  OSMesaPixelStore(OSMESA_Y_UP, 0);

  OSMesaColorClamp(GL_TRUE);

  window = orb_window_new_flags(-1, -1, width, height, "Gears", ORB_WINDOW_ASYNC);

  init();

  reshape(width, height);

  char running = 1;
  while (running) {
   idle();

   void * event_iter = orb_window_events(window);

   OrbEventOption event_option;
   do {
     event_option = orb_events_next(event_iter);
     switch (event_option.tag) {
       case OrbEventOption_Quit:
         running = 0;
         break;
       default:
         break;
     }
   } while (running && event_option.tag != OrbEventOption_None);

   orb_events_destroy(event_iter);
  }

  orb_window_destroy(window);
  OSMesaDestroyContext(ctx);
  free(buffer);

  return 0;             /* ANSI C requires main to return int. */
}