gluProject.3G man page
gluProject — map object coordinates to window coordinates
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.
Specifies the current modelview matrix (as from a glGetDoublev() call).
Specifies the current projection matrix (as from a glGetDoublev() call).
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 GLU_TRUE indicates success, a return value of GLU_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 × M × v
where P is the current projection matrix proj and M is the current modelview matrix model (both represented as 4 × 4 matrices in column-major order).
The window coordinates are then computed as follows:
winX = view 0 + view 2 × v ″ 0 + 1 2
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