GLUUNPROJECT4(3G)

✨ NAME ✨

okay bestie, welcome to the 3G manual page for gluUnProject4 💖 — the icon that maps window and clip coordinates to object coordinates. no cap, that’s the whole name-vibe: map window and clip coordinates to object coordinates. periodt. 👑

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💖 C SPECIFICATION 💖

here’s the signature exactly, character for character, because we do not play with prototypes, fr fr:

       GLint gluUnProject4( GLdouble winX,
                            GLdouble winY,
                            GLdouble winZ,
                            GLdouble clipW,
                            const GLdouble *model,
                            const GLdouble *proj,
                            const GLint *view,
                            GLdouble near,
                            GLdouble far,
                            GLdouble* objX,
                            GLdouble* objY,
                            GLdouble* objZ,
                            GLdouble* objW )

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🎀 PARAMETERS 🎀

• winX, winY, winZ — specify the window coordinates to be mapped. window coords, bestie, the ones you wanna map. 🪟✨
• clipW — specify the clip w coordinate to be mapped. yes, the w. we love a w. 💅
• model — specifies the modelview matrix (as from a glGetDoublev call). modelview tea ☕
• proj — specifies the projection matrix (as from a glGetDoublev call). projection tea ☕
• view — specifies the viewport (as from a glGetIntegerv call). viewport tea ☕
• near, far — specify the near and far planes (as from a glGetDoublev call). near/far planes, iconic. 🎀
• objX, objY, objZ, objW — returns the computed object coordinates. the outputs, the main characters, the returns. 👑

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🌸 DESCRIPTION 🌸

okay so gluUnProject4 maps the specified window coordinates winX, winY and winZ and its clip w coordinate clipW into object coordinates (objX, objY, objZ, objW) using model, proj and view. literally the reverse-glow-up pipeline. 💅

clipW can be other than 1 as for vertices in glFeedbackBuffer when data type GL_4D_COLOR_TEXTURE is returned. not me being flexible with w, but yes. This also handles the case where the near and far planes are different from the default, 0 and 1, respectively. so if your near/far are not the default 0 and 1, it still eats. 🍓

A return value of GL_TRUE indicates success; a return value of GL_FALSE indicates failure. so check that vibe check, bestie — success vs failure, no in-between. 😭

To compute the coordinates (objX, objY, objZ and objW), gluUnProject4 multiplies the normalized device coordinates by the inverse of model*proj as follows:

                           objX
                          ⎝objY⎠=INV(PM)⎝_______________−1⎠
                           objZ          _______________−1
                           objW           ____________−1
                                               clipW

INV() denotes matrix inversion. the math is mathing, periodt. 🔥

gluUnProject4 is equivalent to gluUnProject when clipW is 1, near is 0 and far is 1. so if those are your settings, it’s giving same energy as gluUnProject. 🌈

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💅 NOTES 💅

gluUnProject4 is available only if the GLU version is 1.3 or greater. no old-GLU crumbs, bestie — 1.3+ or nothing. 👑

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🦋 SEE ALSO 🦋

• glGet(3G)
• glFeedbackBuffer(3G)
• gluProject(3G)
• gluUnProject(3G)

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bye bestie 💖 that’s the whole gluUnProject4 moment from the 3G manual. the footer is just the manual tag — no extra source/version/date tea on this one — so consider this your cute sign-off. mwah 💋✨