R: [Plib-users] gluUnProject help!

[Paolo L. <p.l...@ci...>]

Don't know if it's useful to you, this is the code I use taken from a =
recent
post to the list:


int Project2d3d ( int x2, int y2, float& x3, float& y3, float& z3 )
// does transform 2d into 3d coordinates
{
	GLint viewport[4] ;
	GLdouble modvmatrix[16], projmatrix[16] ;

	glGetIntegerv ( GL_VIEWPORT, viewport ) ;
	/* OpenGL y starts at lower left, X/Windows y starts at top left */
	GLdouble y2gl =3D viewport[3] - y2 ;

	/* Update the Modelview and Projectionmatrix */
	glMatrixMode ( GL_MODELVIEW ) ;  ssgLoadModelviewMatrix () ;
	glMatrixMode ( GL_PROJECTION ) ; ssgLoadProjectionMatrix () ;

	/* Use GL power to find the depth of the projection */
	GLfloat z2 ;
	glReadPixels ( x2, y2gl, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &z2 ) ;
	if ( z2 >=3D 1 ) return 0;

	/* Some more GL magic. Get the projection and modelview matrices */
	glGetDoublev (  GL_MODELVIEW_MATRIX,  modvmatrix ) ;
	glGetDoublev (  GL_PROJECTION_MATRIX, projmatrix ) ;

	GLdouble dx, dy, dz ;

	/* convert screen coords to object coords. */
	int retcode =3D gluUnProject ( x2, y2gl, z2, modvmatrix, projmatrix,
viewport, &dx, &dy, &dz ) ;
	x3 =3D dx ;
	y3 =3D dy ;
	z3 =3D dz ;
	return retcode;
}

Greetings -

Paolo Leoncini


> -----Messaggio originale-----
> Da: pli...@li...=20
> [mailto:pli...@li...] Per conto di=20
> Tinoshi Kitazawa
> Inviato: luned=EC 23 gennaio 2006 20.40
> A: pli...@li...
> Oggetto: [Plib-users] gluUnProject help!
>=20
>=20
> Hello everybody!
>=20
> Do you know how to use the gluUnProject with PLIB??? I need=20
> to do something=20
> like Sim City, so I have a terrain (a scenegraph) built using=20
> PLIB, and I=20
> need to put objects over it clicking with mouse! I'm trying to=20
> gluUnProject(x,y,0.0,...) and gluUnProject(x,y,1.0,...), and=20
> I create a=20
> sgLineSegment3 to connect the two points. Then I'd like to=20
> ssgLOS() this=20
> line with the scenegraph... but I'm going crazy!!! Do you=20
> know a easier way=20
> to do something like that??? Thanks!!!=20
>=20
>=20
>=20
> -------------------------------------------------------
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