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- zzzzcccclllleeeeaaaarrrr((((3333GGGG)))) zzzzcccclllleeeeaaaarrrr((((3333GGGG))))
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- NNNNAAAAMMMMEEEE
- zzzzcccclllleeeeaaaarrrr - initializes the z-buffer of the current framebuffer
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- CCCC SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN
- vvvvooooiiiidddd zzzzcccclllleeeeaaaarrrr((((vvvvooooiiiidddd))))
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- PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRRSSSS
- _n_o_n_e
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- DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
- zzzzcccclllleeeeaaaarrrr sets the z-buffer in the area of the viewport to the largest
- positive z value supported. When multisample is enabled, and multisample
- buffers exist in the current framebuffer configuration in the current
- drawmode, this value is equal to ggggeeeettttggggccccoooonnnnffffiiiigggg((((GGGGCCCC____MMMMSSSS____ZZZZMMMMAAAAXXXX)))).... Otherwise, it is
- equal to ggggeeeettttggggccccoooonnnnffffiiiigggg((((GGGGCCCC____ZZZZMMMMAAAAXXXX)))).... Typically zzzzcccclllleeeeaaaarrrr is called prior to
- rendering each frame. If you intend to clear the color bitplanes as well
- as the z-buffer, or if you require control of the value written to the
- z-buffer, call cccczzzzcccclllleeeeaaaarrrr instead of zzzzcccclllleeeeaaaarrrr.
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- Because only the normal framebuffer includes a z buffer, zzzzcccclllleeeeaaaarrrr should be
- called only while draw mode is NNNNOOOORRRRMMMMAAAALLLLDDDDRRRRAAAAWWWW. Also, the current z writemask
- controls which z-buffer bitplanes are modified during zzzzcccclllleeeeaaaarrrr execution,
- and screenmask, when it is set to a subregion of the viewport, bounds the
- cleared region. Other drawing modes, including polygon fill pattern,
- stenciling, texture mapping, writemask, and z buffering, have no effect
- on the operation of zzzzcccclllleeeeaaaarrrr.
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- After zzzzcccclllleeeeaaaarrrr executes, the graphics position is undefined.
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- SSSSEEEEEEEE AAAALLLLSSSSOOOO
- drawmode, getgconfig, scrmask, setpattern, stencil, texbind, wmpack,
- writemask, zbuffer, zwritemask
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- NNNNOOOOTTTTEEEE
- On the Personal Iris, for performance reasons, the z-buffer is not
- physically cleared when zzzzcccclllleeeeaaaarrrr is called. Z-buffering works as it
- normally would unless an attempt is made to read back data from the z-
- buffer. In situations where this is necessary, cccczzzzcccclllleeeeaaaarrrr should be used
- instead of zzzzcccclllleeeeaaaarrrr. When using cccczzzzcccclllleeeeaaaarrrr, the z-buffer will be physically
- cleared to the specified value, if the specified value is in the range
- -0x800001 to 0x7ffffe.
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- For performance reasons, XS, XS24, XZ, Elan and Extreme products do not
- physically clear the z-buffer when calling zzzzcccclllleeeeaaaarrrr. On these systems, the
- LSB of the z-buffer is used as a flag bit to signal that the z-buffer has
- been cleared. The 23 remaining bits are used for the z comparison. In
- order to physically clear the z-buffer, first call zzzzffffuuuunnnnccccttttiiiioooonnnn((((ZZZZFFFF____AAAALLLLWWWWAAAAYYYYSSSS)))),
- then draw a polygon whose z coordinates map to the desired z value. To
- avoid updating the framebuffer, call wwwwmmmmppppaaaacccckkkk((((0000)))) before drawing. Restore
- the writemask and z function afterwards.
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- PPPPaaaaggggeeee 1111
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