GLUPROJECT(3G)GLUPROJECT(3G)NAMEgluProject - 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.
DESCRIPTIONgluProject 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
"winZ" ~=~ (v sup prime (2) ~+~ 1)~/~ 2
SEE ALSOglGet(3G), gluUnProject(3G)
March 1, 2011
