GLUPERSPECTIVE(3G)

🌸 NAME 🌸

okay bestie, welcome to the GLUPERSPECTIVE(3G) page. This is all about gluPerspective — the function that sets up a perspective projection matrix. ✨

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💅 C SPECIFICATION 💅

Here's the exact signature, no cap:

       void gluPerspective( GLdouble fovy,
                            GLdouble aspect,
                            GLdouble zNear,
                            GLdouble zFar )

       delim $$

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🎀 PARAMETERS 🎀

• fovy — specifies the field of view angle, in degrees, in the y direction. vertical angle vibes.
• aspect — specifies the aspect ratio that determines the field of view in the x direction. The aspect ratio is the ratio of x (width) to y (height). x over y, periodt.
• zNear — specifies the distance from the viewer to the near clipping plane (always positive). always positive, bestie.
• zFar — specifies the distance from the viewer to the far clipping plane (always positive). also always positive.

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🦋 DESCRIPTION 🦋

gluPerspective specifies a viewing frustum into the world coordinate system. In general, the aspect ratio in gluPerspective should match the aspect ratio of the associated viewport. For example, $ "aspect" ~=~ 2.0 $ means the viewer's angle of view is twice as wide in x as it is in y. If the viewport is twice as wide as it is tall, it displays the image without distortion. slay, no distortion ✨

The matrix generated by gluPerspective is multiplied by the current matrix, just as if glMultMatrix were called with the generated matrix. To load the perspective matrix onto the current matrix stack instead, precede the call to gluPerspective with a call to glLoadIdentity. matrix math, but make it fashion 💅

Given f defined as follows:

                        f  ~=~ cotangent"("{"fovy" over 2}")"

The generated matrix is:

                            left ( ~~ down 130 { matrix {
          ccol { {f over "aspect"} above 0 above 0 above 0 }
          ccol { 0 above f above 0 above 0 }
          ccol { 0 above 0 above {{"zFar" + "zNear"} over {"zNear" - "zFar"}}
       above -1 }
          ccol { 0 above 0 above {{2 * "zFar" * "zNear"} over {"zNear" -
       "zFar"}} above 0} }}  ~~~ right )

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🔥 NOTES 🔥

Depth buffer precision is affected by the values specified for zNear and zFar. The greater the ratio of zFar to zNear is, the less effective the depth buffer will be at distinguishing between surfaces that are near each other. If

                             $r ~=~ "zFar" over "zNear"$

roughly $log sub 2 r$ bits of depth buffer precision are lost. Because $r$ approaches infinity as zNear approaches 0, zNear must never be set to 0.

⚠️ bestie, that means zNear must never be set to 0. periodt. 💀

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👑 SEE ALSO 👑

• glFrustum(3G)
• glLoadIdentity(3G)
• glMultMatrix(3G)
• gluOrtho2D(3G)

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bye bestie! 🫶 The original footer is just GLUPERSPECTIVE(3G) — no separate source/version/date line was printed, so that's the whole sign-off. mwah 💋