TROGBlog - The Battle of Midway v0.17

RSS Bot · July 14, 2008

With the Atari movie coming up, I've had some motivation to do more coding. I took another look at The Battle of Midway this weekend, and here are the results.

More entitlement.

tbom17.zip ( 14.95K )

Number of downloads: 0

New Features:

tbom16.asm 7/13/08

- Removed unnecessary procedural subroutines, freeing up some ROM and cycles.

- Expanded the ROM out to 8k. VSync and Overscan are in bank1, Kernels are in bank2.

- Displays title with fade-in effect and player's plane.

- Integrated include files into the main .asm file.

tbom17.asm 7/14/08

- Added score display in playfield graphics.

- Added scoring: Bombing the ship 10 points, hitting the enemy Zero, 50 points.

- Added sound effects for crashing airplane.

- Added player life count, and game end when all lives are lost.

- Resets the bomb and bullet when they hit.

To Do:

Remove HMOVE artifact from title screen.

Multiple vectors for AA fire.

Time-based high-res physics engine for Zero.

Proper physics engine for player plane, to allow for engine stalling.

AI to control Zero flight patterns.

AI targeting for AA fire and Zero fire.

Known Issues:

- None so far.

Game Controls:

- Press fire to start the game.

- Left and right control the pitch of the plane. (As in aviation pitch. Ironically, it does also change the pitch of the plane's engine, to represent stress on the engine.)

- Fire button fires the machine guns. The machine guns will overheat if you hold the button too long. I'll probably pull the overheat feature, since it eats a byte of RAM and doesn't add much to the game.

- Pressing down on the controller will drop the bomb.

Development Notes:

One benefit of having all these open projects is I'm getting tons of code reuse. Building 8k ROMs is second nature now, and it only took about half an hour to expand this ROM from 4k to 8K. I also dropped in the score display code from Hunt the Wumpus and from Stellar Fortress to compare them. For now, I'm going to use the Stellar Fortress playfield score display, but it may change back to player graphics before I'm done. My main concern when displaying the score is using as little of the screen realestate as possible, so I try to keep it in 5 scanlines. Either implementation will allow me to display a 7 digit score and a one digit life count.

I had wanted to clear up that HMOVE artifact before posting this, but it's proving troublesome. This is my first attempt at using a cycle 73 HMOVE, which is that much harder when trying to implement it with a 48 bit display. The pixel movement wasn't happening as expected, and the title came out completely garbled. I have two questions about this:

- When it says HMOVE at 73 cycles, does that mean the HMOVE write starts at the 73rd cycle, or ends at the 73rd cycle?

- I'm guessing that all the move registers have to be set to 8 to prevent any motion. This makes the HMCLR register useless in this mode.

So I punted for now, and just displayed the title with the artifact.

As a demo feature, the game will randomly pick one of the two enemy capital ships when you press the reset switch, so you'll see the battleship Yamato more often.

Here's the cartridge label mock-up I posted some time back:

http://www.atariage.com/forums/index.php?a...;showentry=5086