zpr Class Reference

3D Mouse support for OpenGL. More...

#include <zpr.h>

Collaboration diagram for zpr:

Public Member Functions
	zpr ()
	Look at the origin from (0.0,0.0,2.0) with up as (0.0,1.0,0.0) and the field of view 30 degrees.
void	readModelView ()
	Read the model view matrix from OpenGL.
void	readProjection ()
	Read the projection matrix from OpenGL and calculate left, right, bottom, top, zNear and zFar.
void	readScreenDimensions ()
	Read the current screen size from OpenGL.
void	update ()
	Read in the current OpenGL state.
void	write ()
	Write the current projection from zpr's parameters.
void	writeDefault ()
	Write a default projection from zpr.
void	writefromXaxis ()
	Draw having the x and y axes with equal scales, zpr::top needs to be re-calculated.
void	readMouse (GLdouble px, GLdouble py, GLdouble *pz, intc x, intc y) const
	Get the world mouse co-ordinates.
void	printInfo () const
	Print the frustrum values.
Static Public Member Functions
static void	motion (int x, int y)
	Glut motion call back function.
static void	mouse (int button, int state, int x, int y)
	Glut mouse call back function.
static void	reshape (int width_, int height_)
	Glut reshape call back function.
static double	vlen (GLdouble x, GLdouble y, GLdouble z)
	Distance function.
Public Attributes
GLdouble	left
	The minimum x screen coordinate.
GLdouble	right
	The maximum x screen coordinate.
GLdouble	bottom
	The minimum y screen coordinate.
GLdouble	top
	The maximum y screen coordinate.
GLdouble	zNear
	The closest z clipping plane.
GLdouble	zFar
	The farthest z clipping plane.
int	width
	Screen pixel width.
int	height
	Screen pixel height.
int	mouseX
	The mouse X position in pixeles.
int	mouseY
	The mouse Y position in pixeles.
bool	mouseLeft
	Was the left mouse button pressed?
bool	mouseMiddle
	Was the middle mouse button pressed?
bool	mouseRight
	Was the right mouse button pressed?
GLdouble	mouseXworld
	The mouse X position in world coordinates.
GLdouble	mouseYworld
	The mouse Y position in world coordinates.
GLdouble	mouseZworld
	The mouse Z position in world coordinates.
GLdouble	matrix [16]
	The model view matrix.
GLdouble	matrixI [16]
	The inverse of the model view matrix.
fnobj0< void > *	mousecallback
	If not zero callback after mousezpr(.
Static Public Attributes
static zpr *	global = 0
	zpr is a singleton with a global pointer.

Detailed Description

3D Mouse support for OpenGL.

: Mouse Functionality. The left mouse button rotates about the global origin. The right mouse button pans. The third mouse button (hold down left and right for 2 button mouse) zooms.

: Acknowledgements: Thanks to Nigel Stewart at nigels.com for zpr.h and zpr.cpp. I requested permission to use the code as mouse support is great. For the original version see http://www.nigels.com/glt/gltzpr/ .

I have modified the code from C to C++. Additional functionality was added along with a minor optimization.

zpr is currently a singleton class. An instance initializes OpenGL with a reasonable default projection and model view.

Example

  int wx=800; 
  int wy=800;
  glutInitWindowSize(wx,wy);
  glutCreateWindow("");

  zpr zz;

You can make direct OpenGL calls yourself and then have this class read in the new state with zpr::update(). ie

zpr works correctly when its state mirrors that of OpenGL. For example a call to glFrustrum or gluLookAt will change the viewing frustrum and zpr's values will not be the same as OpenGL's, hence zpr will break. Call zpr::update() to update zpr after a change.

Example

  zpr zz;
  ...
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  gluLookAt
  (
    2.0,0.0,3.0, 
    2.0,0.0,0.0, 
    0.0,1.0,0.0
  );

  zz.update();

Definition at line 74 of file zpr.h.

Constructor & Destructor Documentation

zpr::zpr ( )

Look at the origin from (0.0,0.0,2.0) with up as (0.0,1.0,0.0) and the field of view 30 degrees.

Definition at line 331 of file zpr.cpp.

References glerrordisplay(), global, height, motion(), mouse(), mousecallback, mouseLeft, mouseMiddle, mouseRight, mouseXworld, mouseYworld, mouseZworld, readScreenDimensions(), reshape(), update(), width, zFar, and zNear.

00332 {
00333   global = this;
00334 
00335   mouseX = 0;
00336   mouseY = 0;
00337  
00338   mouseLeft   = false;
00339   mouseRight  = false;
00340   mouseMiddle = false;
00341 
00342   mouseXworld = 0.0;
00343   mouseYworld = 0.0;
00344   mouseZworld = 0.0;
00345 
00346   mousecallback = 0;
00347 
00348   //glMatrixMode(GL_MODELVIEW);
00349   //glLoadIdentity();
00350  
00351   readScreenDimensions();
00352 
00353   glMatrixMode(GL_PROJECTION);
00354   glLoadIdentity();
00355 
00356   zNear=1.0;
00357   zFar=10.0;
00358   gluPerspective(30, (GLfloat) width/(GLfloat) height, zNear, zFar);
00359 
00360   glMatrixMode(GL_MODELVIEW);
00361 
00362   glLoadIdentity();
00363   gluLookAt
00364   (
00365     0.0, 0.0, 2.0,  // Eye  - creates a x: [-2,2] y: [-2,2] screen.
00366     0.0, 0.0, 0.0,  // Center
00367     0.0, 1.0, 0.0   // Up
00368   );
00369 
00370 
00371   glerrordisplay();
00372   update();
00373 
00374   glutReshapeFunc(reshape);
00375   glutMouseFunc(mouse);
00376   glutMotionFunc(motion);
00377 }

Member Function Documentation

void zpr::motion	(	int	x,
		int	y
	)			`[static]`

Glut motion call back function.

Definition at line 259 of file zpr.cpp.

References global.

Referenced by zpr().

00260 {
00261   assert(global!=0);
00262   global->motionzpr(x,y);
00263 }

void zpr::mouse	(	int	button,
		int	state,
		int	x,
		int	y
	)			`[static]`

Glut mouse call back function.

Definition at line 198 of file zpr.cpp.

References global.

Referenced by zpr().

00199 {
00200   assert(global!=0);
00201 
00202   global->mousezpr(button,state,x,y);
00203 }

void zpr::printInfo ( ) const

Print the frustrum values.

Definition at line 379 of file zpr.cpp.

References bottom, height, left, right, SHOW, top, width, zFar, and zNear.

Referenced by zprtest::test01(), and zprtest::test03().

00380 {
00381 cout << SHOW(left) << endl;
00382 cout << SHOW(right) << endl;
00383 cout << SHOW(bottom) << endl;
00384 cout << SHOW(top) << endl;
00385 cout << SHOW(zNear) << endl;
00386 cout << SHOW(zFar) << endl;
00387 cout << SHOW(width) << endl;
00388 cout << SHOW(height) << endl;
00389 }

void zpr::readModelView ( )

Read the model view matrix from OpenGL.

Definition at line 142 of file zpr.cpp.

References zprGLmatrix::invertMatrix(), matrix, and matrixI.

Referenced by update().

00143 {
00144   glGetDoublev(GL_MODELVIEW_MATRIX,matrix);
00145   zprGLmatrix::invertMatrix(matrixI,matrix);
00146 }

void zpr::readMouse	(	GLdouble *	px,
		GLdouble *	py,
		GLdouble *	pz,
		intc	x,
		intc	y
	)			const

Get the world mouse co-ordinates.

Definition at line 206 of file zpr.cpp.

Referenced by zprmouse::world().

00213 {
00214 //    Use the ortho projection and viewport information
00215 //    to map from mouse co-ordinates back into world 
00216 //    co-ordinates
00217 
00218   int viewport[4];
00219   glGetIntegerv(GL_VIEWPORT,viewport);
00220 
00221   *px = (GLdouble)(x-viewport[0])/(GLdouble)(viewport[2]);
00222   *py = (GLdouble)(y-viewport[1])/(GLdouble)(viewport[3]);
00223 
00224   *px = left + (*px)*(right-left);
00225   *py = top  + (*py)*(bottom-top);
00226   *pz = zNear;
00227 }

void zpr::readProjection ( )

Read the projection matrix from OpenGL and calculate left, right, bottom, top, zNear and zFar.

Definition at line 480 of file zpr.cpp.

References zprGLmatrix::access(), bottom, glerrordisplay(), left, right, top, zFar, and zNear.

Referenced by zprtest::test03(), and update().

00481 {
00482   static GLdouble pmatrix[16];
00483 
00484   glerrordisplay();
00485 
00486   glGetDoublev(GL_PROJECTION_MATRIX,pmatrix);
00487 
00488   glerrordisplay();
00489 
00490   zprGLmatrix mat(pmatrix);
00491 
00492   GLdouble a[6];
00493   a[0] = mat.access(0,0);
00494   a[1] = mat.access(1,1);
00495   a[2] = mat.access(0,2);
00496   a[3] = mat.access(1,2);
00497   a[4] = mat.access(2,2);
00498   a[5] = mat.access(2,3);
00499 
00500   // This is essentially an inverse of a glFrustrum(...) call.
00501   // Here the input parameters to the glFrustrum call are
00502   // calculated from the projection matrix.
00503   GLdouble c0 = (1.0-a[4])/(1.0+a[4]);
00504   //GLdouble z0 = a[5]*(c0+1.0)*-0.5/c0;
00505   GLdouble z0 = a[5]*(1.0+1.0/c0)*-0.50;
00506   GLdouble z1 = -c0*z0;
00507   GLdouble x0 = z0*(a[2]-1.0)/a[0];
00508   GLdouble x1 = (z0*2.0+a[0]*x0)/a[0];
00509   GLdouble y0 = z0*(a[3]-1.0)/a[1];
00510   GLdouble y1 = (z0*2.0+a[1]*y0)/a[1];
00511 
00512   left = x0;
00513   right = x1;
00514   bottom = y0;
00515   top = y1;
00516   zNear = z0;
00517   zFar = z1;
00518 
00519   glerrordisplay();
00520 }

void zpr::readScreenDimensions ( )

Read the current screen size from OpenGL.

Definition at line 469 of file zpr.cpp.

References glerrordisplay(), height, and width.

Referenced by update(), and zpr().

00470 {
00471   GLint viewport[4];
00472   glGetIntegerv( GL_VIEWPORT, viewport );
00473 
00474   glerrordisplay();
00475 
00476   width = viewport[2];
00477   height = viewport[3];
00478 }

void zpr::reshape	(	int	width_,
		int	height_
	)			`[static]`

Glut reshape call back function.

Definition at line 148 of file zpr.cpp.

References global.

Referenced by zpr().

00149 {
00150   assert(zpr::global!=0);
00151   global->reshapezpr(width_,height_);
00152 }

void zpr::update ( ) [inline]

Read in the current OpenGL state.

Definition at line 117 of file zpr.h.

References readModelView(), readProjection(), and readScreenDimensions().

Referenced by bsptree001::bsptree001(), buttonpanel01test::buttonpanel01test(), maze005::eval(), maze004::eval(), maze003::eval(), maze002::eval(), maze001::eval(), test01obj< P, PD >::eval(), visenv::graphicsloop(), menusystemtest02::menusystemtest02(), menusystemtest03::menusystemtest03(), menusystemtest04::menusystemtest04(), cubegui::prog01(), gobjtest::test001(), windowscaleD2test::test002(), graphmisctest::test002(), gobjtest::test002(), gobjtest::test003(), triangletest::test01(), tetrahedrontest::test01(), plotpolartest::test01(), planeinttest::test01(), diskinttest::test01(), d2simplextest::test01(), circleD2test::test01(), boxOBBhalfspaceD2test::test01(), menusystemtest::test01(), pathlinesegtest::test01(), test01(), vrmltest::test02(), triangletest::test02(), tetrahedrontest::test02(), diskinttest::test02(), menusystemtest::test02(), regionD2linkedtest::test02(), meshpatchtest::test02(), helixtestscope::helixtest::test03(), triangletest::test03(), diskinttest::test03(), treeindexedD2test::test03(), meshpatchtest::test03(), meshpatchtest::test04(), triangles3Tdisplaytest::test05(), treeindexedD2test::test05(), partitionstest::test06(), zprmouse::update(), zpr(), and openwindowresource::~openwindowresource().

00118   {
00119     readScreenDimensions();
00120     readModelView();
00121     readProjection();
00122   }

static double zpr::vlen	(	GLdouble	x,
		GLdouble	y,
		GLdouble	z
	)			`[inline, static]`

Distance function.

Definition at line 179 of file zpr.h.

00180     { return sqrt(x*x+y*y+z*z); }

void zpr::write ( )

Write the current projection from zpr's parameters.

Definition at line 154 of file zpr.cpp.

References bottom, glerrordisplay(), height, left, right, top, width, zFar, and zNear.

Referenced by writeDefault(), and writefromXaxis().

00155 {
00156   glViewport(0,0,width,height);
00157 
00158   glMatrixMode(GL_PROJECTION);
00159   glLoadIdentity();
00160   assert(zNear>0.0);
00161   assert(zFar>zNear);
00162   glFrustum(left,right,bottom,top,zNear,zFar);
00163   glMatrixMode(GL_MODELVIEW);
00164 
00165   glerrordisplay();
00166 }

void zpr::writeDefault ( )

Write a default projection from zpr.

Definition at line 181 of file zpr.cpp.

References bottom, height, left, right, top, width, write(), zFar, and zNear.

00182 {
00183   assert( height>0.0);
00184   assert( width>0.0);
00185 
00186   left=-1.0;
00187   right=1.0;
00188 
00189   double dy = (double) height / (double)width;
00190   bottom=-dy;
00191   top=dy;
00192 
00193   zNear=1.0;
00194   zFar=6.0;
00195   write();
00196 }

void zpr::writefromXaxis ( )

Draw having the x and y axes with equal scales, zpr::top needs to be re-calculated.

This function is useful in plotting maths graphs.

Definition at line 391 of file zpr.cpp.

References bottom, height, left, right, top, width, and write().

00392 {
00393   GLdouble const xlen = right - left;
00394   GLdouble const ylen = xlen * (GLdouble) height / (GLdouble) width;
00395   top = bottom + ylen;
00396 
00397   write();
00398 }