/*
 * (c) Copyright 1993, Silicon Graphics, Inc.
 *               1993-1995 Microsoft Corporation
 *
 * ALL RIGHTS RESERVED
 *
 * Please refer to OpenGL/readme.txt for additional information
 *
 */

/*
 *  double.c
 *  This program demonstrates double buffering for 
 *  flicker-free animation.  The left and middle mouse
 *  buttons start and stop the spinning motion of the square.
 */
#include "glos.h"

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glaux.h>

void myinit(void);
void CALLBACK spinDisplay (void);
void CALLBACK startIdleFunc (AUX_EVENTREC *event);
void CALLBACK stopIdleFunc (AUX_EVENTREC *event);
void CALLBACK myReshape(GLsizei w, GLsizei h);
void CALLBACK display(void);

static GLfloat spin = 0.0;

void CALLBACK display(void)
{
    glClear (GL_COLOR_BUFFER_BIT);

    glPushMatrix ();
    glRotatef (spin, 0.0, 0.0, 1.0);
    glRectf (-25.0, -25.0, 25.0, 25.0);
    glPopMatrix ();

    glFlush();
    auxSwapBuffers();
}

void CALLBACK spinDisplay (void)
{
    spin = spin + 2.0;
    if (spin > 360.0)
    spin = spin - 360.0;
    display();
}

void CALLBACK startIdleFunc (AUX_EVENTREC *event)
{
    auxIdleFunc(spinDisplay);
}

void CALLBACK stopIdleFunc (AUX_EVENTREC *event)
{
    auxIdleFunc(0);
}

void myinit (void)
{
    glClearColor (0.0, 0.0, 0.0, 1.0);
    glColor3f (1.0, 1.0, 1.0);
    glShadeModel (GL_FLAT);
}

void CALLBACK myReshape(GLsizei w, GLsizei h)
{
    h = (h == 0) ? 1 : h;
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h) 
    glOrtho (-50.0, 50.0, -50.0*(GLfloat)h/(GLfloat)w, 
        50.0*(GLfloat)h/(GLfloat)w, -1.0, 1.0);
    else 
    glOrtho (-50.0*(GLfloat)w/(GLfloat)h, 
        50.0*(GLfloat)w/(GLfloat)h, -50.0, 50.0, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity ();
}

/*  Main Loop
 *  Open window with initial window size, title bar, 
 *  RGBA display mode, and handle input events.
 */
int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_DOUBLE | AUX_RGB);
    auxInitPosition (0, 0, 500, 500);
    auxInitWindow ("Double Buffering");
    myinit ();
    auxReshapeFunc (myReshape);
    auxIdleFunc (spinDisplay);
    auxMouseFunc (AUX_LEFTBUTTON, AUX_MOUSEDOWN, startIdleFunc);
    auxMouseFunc (AUX_RIGHTBUTTON, AUX_MOUSEDOWN, stopIdleFunc);
    auxMainLoop(display);
    return(0);
}
