gluProject(3)

NAME

       gluProject - map object coordinates to window coordinates

C SPECIFICATION

       GLint gluProject( GLdouble objX,
                         GLdouble objY,
                         GLdouble objZ,
                         const GLdouble *model,
                         const GLdouble *proj,
                         const GLint *view,
                         GLdouble* winX,
                         GLdouble* winY,
                         GLdouble* winZ )

       delim $$

PARAMETERS

       objX, objY, objZ
                       Specify the object coordinates.

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

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

       view            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 model, proj, and view. The result is stored in winX,
       winY, and winZ. A return value of GL_TRUE indicates success,  a  return
       value of GL_FALSE indicates failure.

       To  compute  the coordinates, let $v ~=~ ("objX", "objY", "objZ", 1.0)$
       represented as a matrix with 4 rows and 1 column.  Then gluProject com-
       putes $v sup prime$ as follows:

       v sup prime ~=~ P ~times~ M ~times~ v

       where  $P$  is  the  current projection matrix proj, $M$ is the current
       modelview matrix model (both represented as $4  times  4$  matrices  in
       column-major order) and '$times$' represents matrix multiplication.

       The window coordinates are then computed as follows:

       "winX" ~=~ "view" (0) ~+~ "view" (2) ~*~ (v sup prime (0) ~+~ 1)~/~2

       "winY" ~=~ "view" (1) ~+~ "view" (3)~*~(v sup prime (1) ~+~ 1)~/~2

       "winZ" ~=~ (v sup prime (2)  ~+~ 1)~/~ 2

SEE ALSO

       glGet(3G), gluUnProject(3G)

                                                                GLUPROJECT(3G)