/****************************************************************************** $Id: qt/glbox.cpp   3.3.4   edited May 27 2003 $**** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.**** This file is part of an example program for Qt.  This example** program may be used, distributed and modified without limitation.*******************************************************************************//******************************************************************************** This is a simple QGLWidget displaying a box**** The OpenGL code is mostly borrowed from Brian Pauls "spin" example** in the Mesa distribution******************************************************************************/#include "glbox.h"// Initialize static class variables:// Shared display list id:GLuint GLBox::sharedDisplayList = 0;// Counter keeping track of number of GLBox instances sharing // the display list, so that the last instance can delete it:int GLBox::sharedListUsers = 0;/*!  Create a GLBox widget*/GLBox::GLBox( QWidget* parent, const char* name, const QGLWidget* shareWidget )    : QGLWidget( parent, name, shareWidget ){    xRot = yRot = zRot = 0.0;		// default object rotation    scale = 1.0;			// default object scale    object = 0;    localDisplayList = 0;}/*!  Set up the OpenGL rendering state. Robustly access shared display list.*/void GLBox::initializeGL(){    // Let OpenGL clear to black    qglClearColor( black );     glEnable(GL_DEPTH_TEST);    if ( sharedListUsers == 0 ) {	// No shared list has been made yet	sharedDisplayList = makeObject();	// Make one	object = sharedDisplayList;		// Use it	sharedListUsers++;				// Keep reference count	qDebug( "GLBox %s created shared display list.", name() );    }    else {				// There is a shared diplay list	if ( isSharing() ) {		// Can we access it?	    object = sharedDisplayList;		// Yes, use it	    sharedListUsers++;			// Keep reference count	    qDebug( "GLBox %s uses shared display list.", name() );	}	else {					    localDisplayList = makeObject();	// No, roll our own	    object = localDisplayList;		// and use that	    qDebug( "GLBox %s uses private display list.", name() );	}    }}/*!  Release allocated resources*/GLBox::~GLBox(){    makeCurrent();				// We're going to do gl calls    if ( localDisplayList != 0 ) {		// Did we make our own?	glDeleteLists( localDisplayList, 1 );	// Yes, delete it	qDebug( "GLBox %s deleted private display list.", name() );    }    else {	sharedListUsers--;	// No, we used the shared one; keep refcount	if ( sharedListUsers == 0 ) { 			// Any sharers left?	    glDeleteLists( sharedDisplayList, 1 );	// No, delete it	    sharedDisplayList = 0;	    qDebug( "GLBox %s deleted shared display list.", name() );	}    }}/*!  Paint the box. The actual openGL commands for drawing the box are  performed here.*/void GLBox::paintGL(){    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );    glMatrixMode( GL_MODELVIEW );    glLoadIdentity();    glTranslatef( 0.0, 0.0, -3.0 );    glScalef( scale, scale, scale );    glRotatef( xRot, 1.0, 0.0, 0.0 );     glRotatef( yRot, 0.0, 1.0, 0.0 );     glRotatef( zRot, 0.0, 0.0, 1.0 );    glCallList( object );}/*!  Set up the OpenGL view port, matrix mode, etc.*/void GLBox::resizeGL( int w, int h ){    glViewport( 0, 0, (GLint)w, (GLint)h );    glMatrixMode( GL_PROJECTION );    glLoadIdentity();    glFrustum(-1.0, 1.0, -1.0, 1.0, 1.0, 10.0);}/*!  Generate an OpenGL display list for the object to be shown, i.e. the box*/GLuint GLBox::makeObject(){    GLuint list;    list = glGenLists( 1 );    glNewList( list, GL_COMPILE );    glBegin(GL_QUADS);    /* Front face */    qglColor( green );    glVertex3f(-1.0, 1.0, 1.0);    glVertex3f(1.0, 1.0, 1.0);    glVertex3f(1.0, -1.0, 1.0);    glVertex3f(-1.0, -1.0, 1.0);    /* Back face */    qglColor( yellow );    glVertex3f(-1.0, 1.0, -1.0);    glVertex3f(1.0, 1.0, -1.0);    glVertex3f(1.0, -1.0, -1.0);    glVertex3f(-1.0, -1.0, -1.0);    /* Top side face */    qglColor( blue );    glVertex3f(-1.0, 1.0, 1.0);    glVertex3f(1.0, 1.0, 1.0);    glVertex3f(1.0, 1.0, -1.0);    glVertex3f(-1.0, 1.0, -1.0);    /* Bottom side face */    qglColor( red );    glVertex3f(-1.0, -1.0, 1.0);    glVertex3f(1.0, -1.0, 1.0);    glVertex3f(1.0, -1.0, -1.0);    glVertex3f(-1.0, -1.0, -1.0);    glEnd();    glEndList();    return list;}/*!  Set the rotation angle of the object to \e degrees around the X axis.*/void GLBox::setXRotation( int degrees ){    xRot = (GLfloat)(degrees % 360);    updateGL();}/*!  Set the rotation angle of the object to \e degrees around the Y axis.*/void GLBox::setYRotation( int degrees ){    yRot = (GLfloat)(degrees % 360);    updateGL();}/*!  Set the rotation angle of the object to \e degrees around the Z axis.*/void GLBox::setZRotation( int degrees ){    zRot = (GLfloat)(degrees % 360);    updateGL();}