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cccczzzzcccclllleeeeaaaarrrr((((3333GGGG)))) cccczzzzcccclllleeeeaaaarrrr((((3333GGGG)))) NNNNAAAAMMMMEEEE cccczzzzcccclllleeeeaaaarrrr - clears the color bitplanes and the z-buffer simultaneously CCCC SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN vvvvooooiiiidddd cccczzzzcccclllleeeeaaaarrrr((((uuuunnnnssssiiiiggggnnnneeeedddd lllloooonnnngggg ccccvvvvaaaallll,,,, lllloooonnnngggg zzzzvvvvaaaallll)))) PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRRSSSS _c_v_a_l expects the color to which you want to clear the color bitplanes. _z_v_a_l expects the depth value to which you want to clear the z-buffer. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN cccczzzzcccclllleeeeaaaarrrr sets the color bitplanes in the area of the viewport to _c_v_a_l, and the z buffer bitplanes in the area of the viewport to _z_v_a_l. Multiple color bitplane buffers can be cleared simultaneously using the bbbbaaaacccckkkkbbbbuuuuffffffffeeeerrrr and ffffrrrroooonnnnttttbbbbuuuuffffffffeeeerrrr commands. The screen mask, when it is set to a subregion of the viewport, bounds the cleared region. Most other drawing modes, including alpha function, blend function, logical operation, polygon fill pattern, stenciling, texture mapping, writemask, zwritemask, and z buffering, have no effect on the operation of cccczzzzcccclllleeeeaaaarrrr. The current color does not change. Because only the normal framebuffer includes a z buffer, cccczzzzcccclllleeeeaaaarrrr should be called only while draw mode is NNNNOOOORRRRMMMMAAAALLLLDDDDRRRRAAAAWWWW. In RGB mode, the _c_v_a_l parameter expects a packed integer of the same format used by ccccppppaaaacccckkkk, namely 0x_a_a_b_b_g_g_r_r, where _r_r is the red value, _b_b the blue value, _g_g the green value, and _a_a is the alpha value. In color map mode this parameter expects an index into the current color map, so only up to 12 of the least-significant bits are significant. The valid range of the _z_v_a_l parameter depends on the graphics hardware. When multisample is enabled, and multisample buffers exist in the current framebuffer configuration in the current drawmode, the minimum is the value returned by ggggeeeettttggggccccoooonnnnffffiiiigggg((((GGGGCCCC____MMMMSSSS____ZZZZMMMMIIIINNNN)))) and the maximum is the value returned by ggggeeeettttggggccccoooonnnnffffiiiigggg((((GGGGCCCC____MMMMSSSS____ZZZZMMMMAAAAXXXX)))). Otherwise, the minimum is the value returned by ggggeeeettttggggccccoooonnnnffffiiiigggg((((GGGGCCCC____ZZZZMMMMIIIINNNN)))) and the maximum is the value returned by ggggeeeettttggggccccoooonnnnffffiiiigggg((((GGGGCCCC____ZZZZMMMMAAAAXXXX)))). It is unaffected by the state of the GLC_ZRANGEMAP compatibility mode (see ggggllllccccoooommmmppppaaaatttt). After cccczzzzcccclllleeeeaaaarrrr executes, the graphics position is undefined. SSSSEEEEEEEE AAAALLLLSSSSOOOO afunction, blendfunction, clear, cpack, getgdesc, glcompat, logicop, scrmask, setpattern, stencil, texbind, wmpack, writemask, zbuffer, zclear, zfunction NNNNOOOOTTTTEEEESSSS Whenever you need to clear both the z-buffer and the color bitplanes to constant values at the same time, use cccczzzzcccclllleeeeaaaarrrr. A simultaneous clear will take place if circumstances allow it. There is never a penalty in calling cccczzzzcccclllleeeeaaaarrrr over calling cccclllleeeeaaaarrrr and zzzzcccclllleeeeaaaarrrr sequentially. PPPPaaaaggggeeee 1111 cccczzzzcccclllleeeeaaaarrrr((((3333GGGG)))) cccczzzzcccclllleeeeaaaarrrr((((3333GGGG)))) IRIS-4D GT and GTX models can do a simultaneous clear only under the following circumstances: +o In RGB mode, the 24 least significant bits of _c_v_a_l (red, green, and blue) must be identical to the 24 least significant bits of _z_v_a_l. +o In color map mode, the 12 least significant bits of _c_v_a_l must be identical to the 12 least significant bits of _z_v_a_l. IRIS-4D VGX models always clear color and z bitplanes banks sequentially, regardless of the values of _c_v_a_l and _z_v_a_l. On the Personal Iris, XS, XS24, XZ, Elan and Extreme, you can speed up cccczzzzcccclllleeeeaaaarrrr by as much as a factor of four for common values of _z_v_a_l if you call zzzzffffuuuunnnnccccttttiiiioooonnnn in conjunction with it such that one of the following conditions are met: _____________________________________________ _z_v_a_l | zzzzffffuuuunnnnccccttttiiiioooonnnn _____________________________________________ ggggeeeettttggggddddeeeesssscccc((((GGGGDDDD____ZZZZMMMMIIIINNNN)))) ZZZZFFFF____GGGGRRRREEEEAAAATTTTEEEERRRR _o_r ZZZZFFFF____GGGGEEEEQQQQUUUUAAAALLLL ggggeeeettttggggddddeeeesssscccc((((GGGGDDDD____ZZZZMMMMAAAAXXXX)))) ZZZZFFFF____LLLLEEEESSSSSSSS _o_r ZZZZFFFF____LLLLEEEEQQQQUUUUAAAALLLL _____________________________________________ ||||| ||||| Iris Indigo, Indy, and XL systems have a 32-bit zbuffer so use ggggeeeettttggggddddeeeesssscccc((((GGGGDDDD____ZZZZMMMMAAAAXXXX)))) to get the maximum z value and ggggeeeettttggggddddeeeesssscccc((((GGGGDDDD____ZZZZMMMMIIIINNNN)))) to get the minimum z value. For performance reasons, Elan, XS, and XS24 products do not physically clear the z-buffer when calling cccczzzzcccclllleeeeaaaarrrr. 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. BBBBUUUUGGGGSSSS IRIS-4D G models always clear their z-buffers to GGGGDDDD____ZZZZMMMMAAAAXXXX, regardless of the value passed to cccczzzzcccclllleeeeaaaarrrr. PPPPaaaaggggeeee 2222 
