gluProject3x

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 )

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Parameters

Overview

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 $v sup prime$ 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 .EN

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