# Changes

,  18:07, 27 April 2009
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{{regsimple | GX_XF_VIEWPORT_X0 | addr=0x101A | bits=32 | access = R/W}}
* 0x101A: This register defines the X0 coordinate of the viewport.
{{regsimple | GX_XF_VIEWPORT_Y0 | addr=0x101B | bits=32 | access = R/W}}
* 0x101B: This register defines the Y0 coordinate of the viewport.
{{regsimple | GX_XF_VIEWPORT_Z | addr=0x101C | bits=32 | access = R/W}}
* 0x101C: This register defines the depth (far plane - near plane) of the viewport.
{{regsimple | GX_XF_VIEWPORT_X1 | addr=0x101D | bits=32 | access = R/W}}
* 0x101D: This register defines the X1 coordinate of the viewport.
{{regsimple | GX_XF_VIEWPORT_Y1 | addr=0x101E | bits=32 | access = R/W}}
* 0x101E: This register defines the Y1 coordinate of the viewport.
{{regsimple | GX_XF_VIEWPORT_FP | addr=0x101F | bits=32 | access = R/W}}
* 0x101F: This register defines the far plane of the viewport.
All the other viewport registers are 32-bit floating-point values.

===XF projection registers===

These registers define the projection matrix.
Actually, there are 7 registers, so they don't really define a matrix, but rather parts of it.

{{regsimple | GX_XF_PROJ_0 | addr=0x1020 | bits=32 | access = R/W}}
{{regsimple | GX_XF_PROJ_1 | addr=0x1021 | bits=32 | access = R/W}}
{{regsimple | GX_XF_PROJ_2 | addr=0x1022 | bits=32 | access = R/W}}
{{regsimple | GX_XF_PROJ_3 | addr=0x1023 | bits=32 | access = R/W}}
{{regsimple | GX_XF_PROJ_4 | addr=0x1024 | bits=32 | access = R/W}}
{{regsimple | GX_XF_PROJ_5 | addr=0x1025 | bits=32 | access = R/W}}
* These registers define 6 projection values.

{{regsimple | GX_XF_PROJ_MODE | addr=0x1026 | bits=32 | access = R/W}}
* This register defines how the projection values will be translated.

Depending on GX_XF_PROJ_MODE, you must assign different parts of your 4x4 projection matrix to the projection values:
* GX_XF_PROJ_MODE = 0 (perspective):
** GX_XF_PROJ_0 = matrix
** GX_XF_PROJ_1 = matrix
** GX_XF_PROJ_2 = matrix
** GX_XF_PROJ_3 = matrix
** GX_XF_PROJ_4 = matrix
** GX_XF_PROJ_5 = matrix
* GX_XF_PROJ_MODE = 1 (orthographic):
** GX_XF_PROJ_0 = matrix
** GX_XF_PROJ_1 = matrix
** GX_XF_PROJ_2 = matrix
** GX_XF_PROJ_3 = matrix
** GX_XF_PROJ_4 = matrix
** GX_XF_PROJ_5 = matrix
''Note: these assignments are taken from the libogc function GX_LoadProjectionMtx().''
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