DOUBLE.C

/* 
 * (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) 
{ 
    if (!h) return; 
    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); 
}