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/****************************************************************************
**
** Copyright (C) 1992-2008 Trolltech ASA. 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();
}
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