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Manual Reference Pages  - GLUPROJECT (3G)

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gluProject - map object coordinates to window coordinates

CONTENTS

C Specification
Parameters
Description
See Also

GLint gluProject( GLdouble objX,

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

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.

 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 computes v^' as follows:

v^' = P times M times v

where P is the current projection matrix proj, M is the current modelview matrix model (both represented as 4times4 matrices in column-major order) and ’times’ represents matrix multiplication.

The window coordinates are then computed as follows:

winX = view(0) + view(2) * (v^' (0) + 1) / 2

winY = view(1) + view(3) * (v^' (1) + 1) / 2

winZ = (v^' (2) + 1) / 2

glGet(3G),  gluUnProject(3G)

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