FT800 Series Programmer Guide
Version 2.1
Document Reference No.: BRT_000030 Clearance No.: BRT#037
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Copyright © Bridgetek Limited
The COLOR_RGB command changes the current drawing color, which colors the bitmap.
The COLOR_A command changes the current drawing alpha, changing the transparency
of the drawing: an alpha of 0 means fully transparent and an alpha of 255 is fully
opaque. Here a value of 150 gives a partially transparent effect.
2.5.7
VERTEX2II and VERTEX2F
The VERTEX2II command used above only allows positive screen coordinates. If the
bitmap is partially off screen, for example during a screen scroll, then it is necessary to
specify negative screen coordinates. The VERTEX2F command allows negative
coordinates. It also allows fractional coordinates, because it specifies screen (x,y) in
units of 1/16 of a pixel.
For example, drawing the same bitmap at screen position (-10,-10) using VERTEX2F: