/****************************************************************************** $Id: qt/gear.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.*******************************************************************************///// Draws a gear.//// Portions of this code have been borrowed from Brian Paul's Mesa// distribution.//#include <qgl.h>#include <qapplication.h>#include <math.h>#if defined(Q_CC_MSVC)#pragma warning(disable:4305) // init: truncation from const double to float#endif/* * Draw a gear wheel.  You'll probably want to call this function when * building a display list since we do a lot of trig here. * * Input:  inner_radius - radius of hole at center *	   outer_radius - radius at center of teeth *	   width - width of gear *	   teeth - number of teeth *	   tooth_depth - depth of tooth */static void gear( GLfloat inner_radius, GLfloat outer_radius, GLfloat width,		  GLint teeth, GLfloat tooth_depth ){    GLint i;    GLfloat r0, r1, r2;    GLfloat angle, da;    GLfloat u, v, len;    r0 = inner_radius;    r1 = outer_radius - tooth_depth/2.0;    r2 = outer_radius + tooth_depth/2.0;    const double pi = 3.14159264;    da = 2.0*pi / teeth / 4.0;    glShadeModel( GL_FLAT );    glNormal3f( 0.0, 0.0, 1.0 );    /* draw front face */    glBegin( GL_QUAD_STRIP );    for (i=0;i<=teeth;i++) {	angle = i * 2.0*pi / teeth;	glVertex3f( r0*cos(angle), r0*sin(angle), width*0.5 );	glVertex3f( r1*cos(angle), r1*sin(angle), width*0.5 );	glVertex3f( r0*cos(angle), r0*sin(angle), width*0.5 );	glVertex3f( r1*cos(angle+3*da), r1*sin(angle+3*da), width*0.5 );    }    glEnd();    /* draw front sides of teeth */    glBegin( GL_QUADS );    da = 2.0*pi / teeth / 4.0;    for (i=0;i<teeth;i++) {	angle = i * 2.0*pi / teeth;	glVertex3f( r1*cos(angle),      r1*sin(angle),	  width*0.5 );	glVertex3f( r2*cos(angle+da),   r2*sin(angle+da),	  width*0.5 );	glVertex3f( r2*cos(angle+2*da), r2*sin(angle+2*da), width*0.5 );	glVertex3f( r1*cos(angle+3*da), r1*sin(angle+3*da), width*0.5 );    }    glEnd();    glNormal3f( 0.0, 0.0, -1.0 );    /* draw back face */    glBegin( GL_QUAD_STRIP );    for (i=0;i<=teeth;i++) {	angle = i * 2.0*pi / teeth;	glVertex3f( r1*cos(angle), r1*sin(angle), -width*0.5 );	glVertex3f( r0*cos(angle), r0*sin(angle), -width*0.5 );	glVertex3f( r1*cos(angle+3*da), r1*sin(angle+3*da), -width*0.5 );	glVertex3f( r0*cos(angle), r0*sin(angle), -width*0.5 );    }    glEnd();    /* draw back sides of teeth */    glBegin( GL_QUADS );    da = 2.0*pi / teeth / 4.0;    for (i=0;i<teeth;i++) {	angle = i * 2.0*pi / teeth;	glVertex3f( r1*cos(angle+3*da), r1*sin(angle+3*da), -width*0.5 );	glVertex3f( r2*cos(angle+2*da), r2*sin(angle+2*da), -width*0.5 );	glVertex3f( r2*cos(angle+da),   r2*sin(angle+da),	  -width*0.5 );	glVertex3f( r1*cos(angle),      r1*sin(angle),	  -width*0.5 );    }    glEnd();    /* draw outward faces of teeth */    glBegin( GL_QUAD_STRIP );    for (i=0;i<teeth;i++) {	angle = i * 2.0*pi / teeth;	glVertex3f( r1*cos(angle),      r1*sin(angle),	   width*0.5 );	glVertex3f( r1*cos(angle),      r1*sin(angle),	  -width*0.5 );	u = r2*cos(angle+da) - r1*cos(angle);	v = r2*sin(angle+da) - r1*sin(angle);	len = sqrt( u*u + v*v );	u /= len;	v /= len;	glNormal3f( v, -u, 0.0 );	glVertex3f( r2*cos(angle+da),   r2*sin(angle+da),	   width*0.5 );	glVertex3f( r2*cos(angle+da),   r2*sin(angle+da),	  -width*0.5 );	glNormal3f( cos(angle), sin(angle), 0.0 );	glVertex3f( r2*cos(angle+2*da), r2*sin(angle+2*da),  width*0.5 );	glVertex3f( r2*cos(angle+2*da), r2*sin(angle+2*da), -width*0.5 );	u = r1*cos(angle+3*da) - r2*cos(angle+2*da);	v = r1*sin(angle+3*da) - r2*sin(angle+2*da);	glNormal3f( v, -u, 0.0 );	glVertex3f( r1*cos(angle+3*da), r1*sin(angle+3*da),  width*0.5 );	glVertex3f( r1*cos(angle+3*da), r1*sin(angle+3*da), -width*0.5 );	glNormal3f( cos(angle), sin(angle), 0.0 );    }    glVertex3f( r1*cos(0.0), r1*sin(0.0), width*0.5 );    glVertex3f( r1*cos(0.0), r1*sin(0.0), -width*0.5 );    glEnd();    glShadeModel( GL_SMOOTH );    /* draw inside radius cylinder */    glBegin( GL_QUAD_STRIP );    for (i=0;i<=teeth;i++) {	angle = i * 2.0*pi / teeth;	glNormal3f( -cos(angle), -sin(angle), 0.0 );	glVertex3f( r0*cos(angle), r0*sin(angle), -width*0.5 );	glVertex3f( r0*cos(angle), r0*sin(angle), width*0.5 );    }    glEnd();}static GLfloat view_rotx=20.0, view_roty=30.0, view_rotz=0.0;static GLint gear1, gear2, gear3;static GLfloat angle = 0.0;static void draw(){    angle += 2.0;    view_roty += 1.0;    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );    glPushMatrix();    glRotatef( view_rotx, 1.0, 0.0, 0.0 );    glRotatef( view_roty, 0.0, 1.0, 0.0 );    glRotatef( view_rotz, 0.0, 0.0, 1.0 );    glPushMatrix();    glTranslatef( -3.0, -2.0, 0.0 );    glRotatef( angle, 0.0, 0.0, 1.0 );    glCallList(gear1);    glPopMatrix();    glPushMatrix();    glTranslatef( 3.1, -2.0, 0.0 );    glRotatef( -2.0*angle-9.0, 0.0, 0.0, 1.0 );    glCallList(gear2);    glPopMatrix();    glPushMatrix();    glTranslatef( -3.1, 2.2, -1.8 );    glRotatef( 90.0, 1.0, 0.0, 0.0 );    glRotatef( 2.0*angle-2.0, 0.0, 0.0, 1.0 );    glCallList(gear3);    glPopMatrix();    glPopMatrix();}static int timer_interval = 10;			// timer interval (millisec)class GearWidget : public QGLWidget{public:    GearWidget( QWidget *parent=0, const char *name=0 );protected:    void initializeGL();    void resizeGL( int, int );    void paintGL();    void timerEvent( QTimerEvent * );};GearWidget::GearWidget( QWidget *parent, const char *name )     : QGLWidget( parent, name ){    startTimer( timer_interval );}void GearWidget::initializeGL(){    static GLfloat pos[4] = {5.0, 5.0, 10.0, 1.0 };    static GLfloat ared[4] = {0.8, 0.1, 0.0, 1.0 };    static GLfloat agreen[4] = {0.0, 0.8, 0.2, 1.0 };    static GLfloat ablue[4] = {0.2, 0.2, 1.0, 1.0 };    glLightfv( GL_LIGHT0, GL_POSITION, pos );    glEnable( GL_CULL_FACE );    glEnable( GL_LIGHTING );    glEnable( GL_LIGHT0 );    glEnable( GL_DEPTH_TEST );    /* make the gears */    gear1 = glGenLists(1);    glNewList(gear1, GL_COMPILE);    glMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, ared );    gear( 1.0, 4.0, 1.0, 20, 0.7 );    glEndList();    gear2 = glGenLists(1);    glNewList(gear2, GL_COMPILE);    glMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, agreen );    gear( 0.5, 2.0, 2.0, 10, 0.7 );    glEndList();    gear3 = glGenLists(1);    glNewList(gear3, GL_COMPILE);    glMaterialfv( GL_FRONT, GL_AMBIENT_AND_DIFFUSE, ablue );    gear( 1.3, 2.0, 0.5, 10, 0.7 );    glEndList();    glEnable( GL_NORMALIZE );}void GearWidget::resizeGL( int width, int height ){    GLfloat w = (float) width / (float) height;    GLfloat h = 1.0;    glViewport( 0, 0, width, height );    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    glFrustum( -w, w, -h, h, 5.0, 60.0 );    glMatrixMode(GL_MODELVIEW);    glLoadIdentity();    glTranslatef( 0.0, 0.0, -40.0 );}void GearWidget::paintGL(){    draw();}void GearWidget::timerEvent(QTimerEvent*){    updateGL();}int main( int argc, char **argv ){    QApplication::setColorSpec( QApplication::CustomColor );    QApplication a( argc, argv );    if ( !QGLFormat::hasOpenGL() ) {	qWarning( "This system has no OpenGL support. Exiting." );	return -1;    }    if ( argc >= 2 ) {	bool ok = TRUE;	timer_interval = QString::fromLatin1( argv[1] ).toInt( &ok );	if ( !ok )	    timer_interval = 10;    }    GearWidget w;    a.setMainWidget( &w );    w.show();    return a.exec();}