8. Graphics Program to display rotating triangle.

#include <GL/gl.h>

#include <GL/glut.h>

#include <stdlib.h>

void keyPress(unsigned char key, int x, int y)

{

switch(key)

{

case 27:

exit(0);

}

}

void initRendering()

{

glEnable(GL_DEPTH_TEST);

}

void handleResize(int w, int h)

{

glViewport(0,0,w,h);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

gluPerspective(45.0,(double)w/(double)h,1.0,200.0);

}

float _angle=30.0f;

float _cameraAngle=0.0f;

void drawScene()

{

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

glPushMatrix();

glRotatef(_angle, -1.5f, 0.5f, -5.0f);

glBegin(GL_TRIANGLES);

glVertex3f(-0.5f, 0.5f, -5.0f);

glVertex3f(-1.0f, 1.5f, -5.0f);

glVertex3f(-1.5f, 0.5f, -5.0f);

glEnd();

glPopMatrix();

glutSwapBuffers(); }

void update(int value)

{

_angle+=2.0f;

if(_angle>360)

{

_angle-=360;

}

glutPostRedisplay();

glutTimerFunc(25, update, 0);

}

int main(int argc, char** argv)

{

glutInit(&argc, argv);

glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);

glutInitWindowSize(400,400);

glutCreateWindow("My Triangle");

initRendering();

glutDisplayFunc(drawScene);

glutKeyboardFunc(keyPress);

glutReshapeFunc(handleResize);

glutTimerFunc(25, update, 0);

glutMainLoop();

return(0);

}