triangle_square_colour_rotate.c

// This is bloody ugly, but it works! Hooray!
// One of the early NEHE tutorials, compiled using:
// gcc -framework GLUT -framework OpenGL triangle_square_colour_rotate.c -o triangle_square_colour_rotate -Wall

#include <stdio.h>

#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>         /* glut.h includes gl.h and glu.h*/
#endif

GLvoid InitGL(GLvoid);
GLvoid DrawGLScene(GLvoid);
GLvoid ReSizeGLScene(int width, int height);
GLvoid DoIdle(GLvoid);

GLfloat triangle_angle = 0.0f;
GLfloat quad_angle = 0.0f;

GLvoid ReSizeGLScene(int width, int height) 
{
  if (height == 0) {
    height = 1;
  }

  glViewport(0, 0, width, height);

  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();

  gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 100.0f);

  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

GLvoid ProcessKeys(unsigned char key, int x, int y) {
  if (key == 'q')
    exit(0);

  if (key == 'f')
    glutPostRedisplay();
}

GLvoid DoIdle(GLvoid) {
  glutPostRedisplay(); 
}

GLvoid InitGL(GLvoid)
{
  glShadeModel(GL_SMOOTH);
  glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
  
  glClearDepth(1.0f);
  glEnable(GL_DEPTH_TEST);
  glDepthFunc(GL_LEQUAL);

  glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
}

GLvoid DrawGLScene(GLvoid)
{
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glLoadIdentity();
  glTranslatef(-1.5f, 0.0f, -6.0f);

  glRotatef(triangle_angle, 0.0f, 1.0f, 0.0f);

  glBegin(GL_TRIANGLES);
    glColor3f(1.0f, 0.0f, 0.0f);
    glVertex3f(0.0f, 1.0f, 0.0f);

    glColor3f(0.0f, 1.0f, 0.0f);
    glVertex3f(-1.0f,-1.0f, 0.0f);

    glColor3f(0.0f, 0.0f, 1.0f);
    glVertex3f(1.0f,-1.0f, 0.0f);
  glEnd();

  glLoadIdentity();
  glTranslatef(1.5f, 0.0f, -6.0f);
  glRotatef(quad_angle, 1.0f, 0.0f, 0.0f);

  glColor3f(0.5f, 0.5f, 1.0f);
  glBegin(GL_QUADS);
    glVertex3f(-1.0f, 1.0f, 0.0f);
    glVertex3f( 1.0f, 1.0f, 0.0f);
    glVertex3f( 1.0f,-1.0f, 0.0f);
    glVertex3f(-1.0f,-1.0f, 0.0f);
  glEnd();
  
  triangle_angle += 0.2f;
  quad_angle -= 0.15f;
  
  glFlush();
  glutSwapBuffers();
}

int main(int argc, char** argv)
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
  glutInitWindowSize(800, 600);
  glutInitWindowPosition(200, 200);
  glutCreateWindow(argv[0]);

  glutDisplayFunc(DrawGLScene);
  glutReshapeFunc(ReSizeGLScene);
  glutKeyboardFunc(ProcessKeys);
  glutIdleFunc(DoIdle);

  InitGL();
  glutMainLoop();

  return 0;
}