Commodore 16 User Manual page 42

right alter the height number The command CIRCLE
1,160,100,50,42,90,180 displays only the lower right section of the
circle. To rotate an oval, add the angle of clockwise rotation after the
command, like this example: CIRCLE 1,160,100,100,20,,,30.
Here's a program that uses CIRCLE commands for an interesting
effect. Don't forget to clear your computer's memory by typing in NEW
if you entered the last program
75 PAINT 1, 160, 100
This program will be slightly different each time you RUN it.
MULTI-COLOUR GRAPHICS
The Commodore 16 high resolution graphics give you control over
every single dot or "pixel" on the screen, but you have seen that the
ability to pat colours close together is limited. Most hires programs
can use only one or two colours. For including more different colours.
your computer has a special "In-between" graphics mode called multi-
colour graphics. In multicolour graphics. you control half as many dots
on each row as in hi-res because each dot is twice as wide. You get
160 dots on each row, while still getting 200 rows. There is a trade-off
for the use of multiple colours, which is slightly lower resolution.
To begin using multicolour graphics. review the GRAPHIC command
earlier in this chapter. You'll see that the multi-colour screen without
text is GRAPHIC 3 and the multi-colour screen with 5 lines of text is
GRAPHIC 4.
Now look at the table listing the COLOR command. There are two
areas that we haven't used yet, areas 2 and 3. These areas hold two
extra colours. You can use any of the three colours (1. the text colour;
2. an extra colour: and 3, another extra colour) These colours do not
interfere with each other on the screen the way the hi-res colours do in
some previous programs in this chapter.
This program makes use of multi-colour graphics, showing a "neon
sign" effect.
10 COLOR 0,1
20 COLOR 1,2
30 GRAPHIC 1,1
40 A = RND(1)• 20+ 10
50 FOR L=0 TO 359 STEP A
60 CIRCLE 1, 160, 100, 80, 40„,
70 NEXT L
80 FOR L=1 TO 2000: NEXT L
90 GRAPHIC 0,1
The Paint Command
To make a circle or other shape more than just an outline. you can use
the PAINT command The PAINT command fills In any enclosed area
up to the boundaries formed by lines drawn on the screen. If there are
no lines drawn, the screen is filled right to the edge. The BOX
command has a fill option that colours in boxes and rectangles. The
PAINT command can colour in irregular shapes and other non-uniform
areas on the screen that can't be filled with other commands.
To see what the PAINT command does, add this line to the last
program:
80 I 81