lrectwrite(3G)							lrectwrite(3G)

NAME    [Toc]    [Back]

     rectwrite,	lrectwrite - draws a rectangular array of pixels into the
     frame buffer

C SPECIFICATION    [Toc]    [Back]

     void rectwrite(Screencoord	x1, Screencoord	y1,
		    Screencoord	x2, Screencoord	y2, Colorindex parray[])

     void lrectwrite(x1, y1, x2, y2, parray)
     Screencoord x1, y1, x2, y2;
     unsigned long parray[];

PARAMETERS    [Toc]    [Back]

     x1	      expects the lower-left x coordinate of the rectangular region.

     y1	      expects the lower-left y coordinate of the rectangular region.

     x2	      expects the upper-right x	coordinate of the rectangular region.

     y2	      expects the upper-right y	coordinate of the rectangular region.

     parray   expects the array	which contains the values of the pixels	to be
	      drawn.  For RGBA values, pack the	bits thusly:  0xAABBGGRR,
	      where:

		   AA  contains	the alpha value,
		   BB  contains	the blue value,
		   GG  contains	the green value, and
		   RR  contains	the red	value.

	      RGBA component values range from 0 to 0xFF (255).	 The alpha
	      value will be ignored if blending	is not active and the machine
	      has no alpha bitplanes.

DESCRIPTION    [Toc]    [Back]

     rectwrite and lrectwrite draw pixels taken	from the array parray into the
     specified rectangular frame buffer	region.	The system usually draws
     pixels left-to-right, then	bottom-to-top. All coordinates are relative to
     the lower-left corner of the window, not the screen or viewport.

     Pixels are	written	to the currently active	framebuffer, as	specified by
     drawmode.	Thus, to write pixel values to the overlay bitplanes, for
     example, simply set drawmode to OVERDRAW.

     The number	of pixels in parray is always (x2-x1+1)	* (y2-y1+1). If	the
     zoom factors set by rectzoom are both 1.0,	the screen region x1 through
     x2, y1 through y2,	are filled.  Other zoom	factors	result in filling past
     x2	and/or past y2 (x1,y1 is always	the lower-left corner of the filled
     region).






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lrectwrite(3G)							lrectwrite(3G)



     rectwrite draws an	array of 16-bit	words, and therefore should be used
     only to write color index values.	lrectwrite draws an array of 32-bit
     words.  Based on the current pixmode, lrectwrite can draw pixels of 1, 2,
     4,	8, 12, 16, 24, or 32 bits each.	 Use it	to write packed	RGB or RGBA
     values, color index values, or z values.

     pixmode affects the operation of lrectwrite substantialy, and has no
     effect on the operation of	rectwrite.  By default,	lrectwrite draws 32-
     bit pixels	in the format used by cpack.  Different	pixel sizes,
     framebuffer shifts, scan patterns through the framebuffer,	and strides
     through memory, can all be	specified using	pixmode.

     rectwrite and lrectwrite leave the	current	character position
     unpredictable.

SEE ALSO    [Toc]    [Back]

     blendfunction, dither, lrectread, pixmode,	rectcopy, rectzoom

NOTES    [Toc]    [Back]

     These routines are	available only in immediate mode.

     On	IRIS Indigo, Indy, and XL graphics the pixels written by rectwrite and
     lrectwrite	will be	dithered if dithering is enabled.  To write undithered
     pixels the	dither command must be used to turn dithering off.  On the
     Indigo, if	dithering is on, pixel images written, then read and written
     again will	cause successive dithering to be done each time	the pixels are
     written.  On Indy and XL graphics,	successive dithering will not occur.

     On	Indigo Entry graphics, when in color index mode	with double-buffering
     enabled, 8-bit values are clamped to 4 bits, rather than being masked.

BUGS    [Toc]    [Back]

     IRIS-4D Personal Iris requires that both |x2-x1| and |y2-y1| be less than
     2048.

     IRIS-4D VGX and VGXT require that both |x2-x1+1| and |y2-y1+1| be less
     than 2048.

     The size of the array passed to lrectwrite	is limited to the size of the
     screen.


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