GXSetZMode

C Specification

#include <revolution/gx.h>

void GXSetZMode( 
    GXBool       compare_enable,
    GXCompare    func,
    GXBool       update_enable );

Arguments

compare_enable When GX_TRUE, enables the process for comparing the original Z value and the target Z value. Disabled if not GX_TRUE.

func

Z comparison function. Accepted values are:

Name:	Z compare operation
`GX_NEVER`	Never passes Z test.
`GX_LESS`	Passes if `new Z < existing Z.`
`GX_LEQUAL`	Passes if `new Z <= existing Z`.
`GX_EQUAL`	Passes if `new Z == existing Z`.
`GX_NEQUAL`	Passes if `new Z != existing Z`.
`GX_GEQUAL`	Passes if `new Z >= existing Z`.
`GX_GREATER`	Passes if `new Z > existing Z`.
`GX_ALWAYS`	Always passes Z test.

update_enable When GX_TRUE, allows a Z buffer update.
Although a Z buffer update is only possible when GX_TRUE, the comparison process will continue.

Return Values

None.

Description

This function sets the Z-buffer compare mode. The result of the Z compare is used to conditionally write color values to the Embedded Frame Buffer (EFB).

When compare_enable is set to GX_DISABLE, Z buffering is disabled and the Z buffer is not updated.

The func parameter determines the comparison that is performed. In the comparison function, the newly rasterized Z value is on the left while the Z value from the Z buffer is on the right. If the result of the comparison is false, the newly rasterized pixel is discarded.

The parameter update_enable determines whether or not the Z buffer is updated with the new Z value after a comparison is performed. This parameter also affects whether the Z buffer is cleared during copy operations. See GXCopyDisp and GXCopyTex.

Revision History

2006/03/01 Initial version.