Sinclair ZX80 / ZX81 / Z88 Forums

I am working on game 29. This will be a 2 player artilleryshooter where you need to enter angle and speed to shoot a cannonball to the other. First to hit the other wins.

This is a classic game from the early '80ies and now in development in 1K hires on the ZX81.

I am struggling with the display.
It must become a combined OUTLAW, Marble Racer and Blocky screen to work.
Timing is an issue, but it looks like I have found a way out after hours of trying.

Game 30 will be another great final like game 10 and 20 was.

Example how it might look.

Only way to make the screen work is not to use the final line for display of bullit or cannon.
This can be done by 2 pointers in a address.

How to calculate a hiresscreenroutine.
(and still need to change the order a bit)

And still a display error in the routine.
Now solved and screen even wider than in above routine.
This was an easier solution than the smaller screen.

Left canon now in display.

Now right cannon also added and 48K bug repaired.
Next thing is start a game and set up an initial left and right cannon on a platform.

Then formula to enter angle and speed and fire a cannonball.

Both cannons and each game the platformheight changes.

For the cannonball itself I need full lines over the screen.
Since the cannonball will look like I need 3 lines.

The making of the screen with the cannonball took some effort. Finally the hiresdisplay of the right cannon had a bug
The game can now show the cannons and the lines of the cannonball (even when this is on the line of a cannon).
Next thing to add: the plotting of the cannonball.
After that : shooting the cannonball. Part of the formula is already added in the program.

Remaining space : 261 bytes
To do:
Plotting, controls, part of formula, end of game test

Temporary 40 bytes filler is also codeable.
Remaining 301 bytes.

Cannon now properly loaded, ready to fire.