Radio Shack TRS-80 Operation Manual page 36

computer Graphics Operation Manual
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tiling
Paint Style
tiling is the pattern in a graphics display. By specifying
each pixel, you can produce a multitude of tiling styles
thereby simulating different shades of paint on the screen.
tiling is convenient to use in bar graphs, pie charts,
etc., or whenever you want to shade with a defined pattern.
There are two types of tiling:
•
Numeric expressions
Strings
Numeric Expressions. There are only two numeric
expressions that can be used for the paint style -- ~ and 1.
1 paints all pixels ON (solid white) and ~ paints all pixels
OFF (solid black).
To use numeric expressions, enter either a ~ or 1. For
example:
PAINT (32~,12~),1,1
Strings (point-by-Point painting). You can paint precise
patterns using strings by defining a multi-pixel grid,
pixel-by-pixel, on your screen as one contiguous pattern.
string painting is called "pixel" painting because you are
literally painting the screen "pixel-by-pixel" in a
predetermined order.
You can define the tile length as being one to 64 vertical
tiles, depending on how long you want your pattern. Tile
width, however, is always eight horizontal pixels (8 pixels
representing one 8-bit byte). The dimensions of a tile
pattern are length by width. Tile patterns are repeated as
necessary to paint to the specified borders. Because of its
symmetry, you'll probably find equilateral pixel grids most
convenient.
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