EXPLODE!

by Thurstan Felstead

from Your Sinclair, March 1989



BANG!



Don't you just love explosions (you were wondering what that title was

about weren't you)? I like explosions. Especially those gorgeous, big,

noisy ones with lots of debris you see on posh games. Thurstan "insane"

Felstead seems to like them too. Nice man. He's written a routine so

you can appreciate them. BANG! he called it. (Oo-er!) [Well, he called

it Explode!, actually, but never mind. JimG]



Kaboom!

The routine is in machine code, starts at 61440 and is 912 bytes long.

Not particularly enormous considering the startling and, one might

say, splendiferous effect of the aforementioned routine. Use the Hex

Loader (which is now drawing its pension) to enter the hexadecimal

block and then save the result to tape with SAVE "explode" CODE 61440,912.

But wait! Before you RANDOMIZE USR 61456, examine the following

parameters for information on how to set up your conflagration.



Explode!

There are five variables which must be set up before you can run the

program:



1) The Explosion Window

This is the rectangular area in which the object detonates. It's outer

edges must not touch the edge of the screen in any direction and it

must be larger than the object window (see next reference). To create

a window, you need to POKE the top left co-ordinates and bottom right

co-ordinates in the following way:

POKE 61440, top left x co-ordinate (4-251)

POKE 61442, top left y co-ordinate (4-171)

POKE 61441, bottom right x co-ordinate (4-251)

POKE 61443, bottom right y co-ordinate (4-171)



2) The Object Window

This is the rectangular area that contains the object to be ignited.

It is set up in the same way as the explosion window but it must be

smaller. POKE its variables like this:

POKE 61445, top left x co-ordinate

POKE 61447, top left y co-ordinate

POKE 61446, bottom right x co-ordinate

POKE 61448, bottom right y co-ordinate



3) Gravity

This factor governs the amount of weight attributed to the exploding

pixels. POKE 61444 with the following factors of your choice:

0 - no gravity whatsoever

1 - pretty damn strong gravity

2 - slightly weaker

3 - getting weaker

4 - shuffling toward wimpiness

5 - Phil South



4) Explosion Speed

This variable affects the speed the object fulminates (good word, eh?)

at. Choose the numbers to POKE into the address 61449:

0 - normal explosion speed

1 - slow

2 - slower

3 - slower still

4 - barely moving

5 - as stiff as a board



5) Velocity

This cunning parameter decides the speed at which the particle erupt.

Choose a speed from 1 to 255 and then:

POKE 61450, INT (velocity/2)

POKE 61451, velocity



Now if all that isn't simple then I wear a toupee. And there's a

demonstration as well to eradicate your confusion completely. But

remember BANG! can only handle a maximum of eight hundred pixels or

else it goes gah-gah (just like its author).