Commodore 64 Manual de usuario descargar pdf (Pagina 76)

LINE90:

N EXTX

LINE 95

END

LINES100-109

DATA

After the sprite has become one of the 3 different

shapes defined by the DATA, only then is it

allowed to move across the screen. It will jump 3

X positions at a time (instead of scrolling smoothly

one position at a time, which is also possible).

STEPping 3 positions at a time makes the mouse

"dance" faster across the screen. NEXTX matches

the FOR. . . X position loop. in line 50.

ENDs the program, which occurs when the sprite

moves off the screen.

The sprite shapes are read from the data num-

bers, in order. First the 63 numbers which com-

prise sprite shape 1 are read, then the 63 num-

bers for sprite shape 2, and then sprite shape 3.

This data is permanently read into the.3 memory

locations and after it is read into these locations,

all the program has to do is point sprite 0 at the

3 memory locations and the sprite automatically

takes the shape of the data in those locations.

We are pointing the sprite at 3 locations one at a

time which produces the "animation" effect. If

you want to see how these numbers affect each

sprite, try changing the first 3 numbers in liNE

100 to 255, 255, 255. See the section on defining

sprite shapes for more information.

174 PROGRAMMING GRAPHICS

1 2 ... 71 72 73 74 75 76 77 78 79 80 81 82 83

Sin comentarios

Commodore 64 Manual de usuario Pagina 76