Cocoa Design Patterns
Learning OpenGL ES for iOS
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    by Erik M. Buck, Donald A. Yacktman
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    Learning OpenGL ES for iOS: A Hands-on Guide to Modern 3D Graphics Programming
    by Erik M. Buck

Errata > Ambiguity regarding frustum┬áspecification

In the section "Perspective and the Viewing Frustum" it states that there is a constraint regarding the specification of a frustum where the near plane Z position cannot be less than zero. It goes on to explain that GLKMatrix4MakeFrustrum flips the sign of the Z axis, due to this constraint. The accompanying diagram (5.8) shows the coordinate system with the inverted Z axis (negative pointing out of the screen, as opposed to into the screen as the convention with OpenGL).

The question I have is whether the constraint referred to above (frustum near plane Z position must be >= zero) refers to the OpenGL orientation of the Z axis, or the inverted Z axis as shown in the diagram. I am also curious to know why this "quirk" with GLKMatrix4MakeFrustrum is a result of the constraint.
May 19, 2013 | Unregistered CommenterEJ