Re: certainly already asked

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Javier Castellar (javier++at++sixty.asd.sgi.com)
Thu, 6 Jun 1996 13:47:52 -0700


>As a future feature suggestion, I would think that being able to access or
>compute the 2D projected coords for objects would be a fairly useful API
>feature?? Just my opinion :-)

We already have this support on the OpenGL Utility lib.

FROM THE OPENGL REFERENCE MANUAL (it is online)
--------------------------------

Convert object coordinates to screen coordinates:

int gluProject (GLdouble objx, GLdouble objy, GLdouble objz, const GLdouble
modelMatrix[16], const GLdouble projMatrix[16], const GLint viewport[4],
GLdouble *winx, GLdouble *winy, GLdouble *winz);

int gluUnProject (GLdouble winx, GLdouble winy, GLdouble winz, const
GLdouble modelMatrix[16], const GLdouble projMatrix[16], const GLint
viewport[4], GLdouble *objx, GLdouble *objy, GLdouble *objz);

FROM THE MAN PAGES
------------------

gluProject(3G) OpenGL Reference gluProject(3G)

NAME
     gluProject - map object coordinates to window coordinates

C SPECIFICATION
     int gluProject( GLdouble objx,
                     GLdouble objy,
                     GLdouble objz,
                     const GLdouble modelMatrix[16],
                     const GLdouble projMatrix[16],
                     const GLint viewport[4],
                     GLdouble *winx,
                     GLdouble *winy,
                     GLdouble *winz )

PARAMETERS
     objx, objy, objz
                     Specify the object coordinates.

     modelMatrix Specifies the current modelview matrix (as from a
                     glGetDoublev call).

     projMatrix Specifies the current projection matrix (as from a
                     glGetDoublev call).

     viewport Specifies the current viewport (as from a glGetIntegerv
                     call).

     winx, winy, winz
                     Return the computed window coordinates.

DESCRIPTION
     gluProject transforms the specified object coordinates into window
     coordinates using modelMatrix, projMatrix, and viewport. The result is
     stored in winx, winy, and winz. A return value of GL_TRUE indicates
     success, and GL_FALSE indicates failure.

SEE ALSO
     glGet, gluUnProject

-----------------------------------------------------------------------------

gluUnProject(3G) OpenGL Reference gluUnProject(3G)

NAME
     gluUnProject - map window coordinates to object coordinates

C SPECIFICATION
     int gluUnProject( GLdouble winx,
                       GLdouble winy,
                       GLdouble winz,
                       const GLdouble modelMatrix[16],
                       const GLdouble projMatrix[16],
                       const GLint viewport[4],
                       GLdouble *objx,
                       GLdouble *objy,
                       GLdouble *objz )

PARAMETERS
     winx, winy, winz
                     Specify the window coordinates to be mapped.

     modelMatrix Specifies the modelview matrix (as from a glGetDoublev
                     call).

     projMatrix Specifies the projection matrix (as from a glGetDoublev
                     call).

     viewport Specifies the viewport (as from a glGetIntegerv call).

     objx, objy, objz
                     Returns the computed object coordinates.

DESCRIPTION
     gluUnProject maps the specified window coordinates into object
     coordinates using modelMatrix, projMatrix, and viewport. The result is
     stored in objx, objy, and objz. A return value of GL_TRUE indicates
     success, and GL_FALSE indicates failure.

SEE ALSO
     glGet, gluProject

-- 
*************************************************************************
* Javier Castellar Arribas     * Email:              javier++at++asd.sgi.com *                 
*                              * Vmail:            		 3-1589 *            
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"Violence is the last refuge of the incompetent"
						Hari Seldon

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