ZealOS/src/Doc/Transform.DD
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$WW,1$$LK,"CDC",A="MN:CDC"$'s have a 4x4 matrix for rotating, scaling, skewing and shifting in 3 dimensions. To make the graphics routines use the transform, you must set the $LK,"DCF_TRANSFORMATION",A="MN:DCF_TRANSFORMATION"$ flag.
The matrix consists of ints that have been scaled 32 bits ($LK,"GR_SCALE",A="MN:GR_SCALE"$). See $LK,"::/Demo/Lectures/FixedPoint.CC"$ to learn why.
See $LK,"Mat4x4IdentEqu",A="MN:Mat4x4IdentEqu"$(), $LK,"Mat4x4IdentNew",A="MN:Mat4x4IdentNew"$(), $LK,"Mat4x4Equ",A="MN:Mat4x4Equ"$() and $LK,"Mat4x4New",A="MN:Mat4x4New"$(). See $LK,"Mat4x4RotX",A="MN:Mat4x4RotX"$(), $LK,"Mat4x4RotY",A="MN:Mat4x4RotY"$(), $LK,"Mat4x4RotZ",A="MN:Mat4x4RotZ"$() and $LK,"Mat4x4Scale",A="MN:Mat4x4Scale"$() to rotate about axes and scale. Combine them with $LK,"Mat4x4MulMat4x4Equ",A="MN:Mat4x4MulMat4x4Equ"$()/$LK,"Mat4x4MulMat4x4New",A="MN:Mat4x4MulMat4x4New"$() and assign them to the $LK,"CDC",A="MN:CDC"$.$FG,2$dc$FG$ with $LK,"DCMat4x4Set",A="MN:DCMat4x4Set"$(). See $LK,"::/Demo/Graphics/Box.CC"$.
You can rotate single points using $LK,"Mat4x4MulXYZ",A="MN:Mat4x4MulXYZ"$().
The 4th dimension allows a neat trick where you can place pos shifts (translations), into the matrix and $LK,"Mat4x4MulMat4x4Equ",A="MN:Mat4x4MulMat4x4Equ"$/$LK,"Mat4x4MulMat4x4New",A="MN:Mat4x4MulMat4x4New"$ them to combine rotation/shift operations. Normally, you can't combine pos shift operations. See $LK,"Mat4x4TranslationEqu",A="MN:Mat4x4TranslationEqu"$() and $LK,"::/Demo/Graphics/Transform.CC"$.
Finally, $LK,"CDC",A="MN:CDC"$'s have an $FG,2$x$FG$, $FG,2$y$FG$ and $FG,2$z$FG$ which is an additional shift (translation).
The transformation is implemented as a callback on the $LK,"CDC",A="MN:CDC"$'s $FG,2$transform()$FG$ member. The default $FG,2$transform()$FG$ callback is $LK,"DCTransform",A="MN:DCTransform"$(). See $LK,"::/Demo/Games/Talons.CC"$ or $LK,"::/Demo/Games/CastleFrankenstein.CC"$ to see how to change the $FG,2$transform()$FG$ callback for foreshortening.