Karateka 2600 - Mockups

[Cybergoth]

Hi Robert!

 

Look at Dolphin for proof of concept.   How did the programmer generate the Dolphin, Octopus, and Sea Weed without flicker?

 

You are fooled by Activision magic. The dolphin and the octopus are only one single sprite each. Take a careful look again. It's just clever shifting and double/quadruple sized pixels.

 

The only two possible Karateka approaches are either doing exact that (-> Double Dragon) or flicker (-> Fu Kung!)

 

Greetings,

Manuel

[+Andrew Davie]

Look at Dolphin for proof of concept.   How did the programmer generate the Dolphin, Octopus, and Sea Weed without flicker?

 

Flicker is your friend.

 

Fu Kung! is planned to be a two player fighter game with large colour sprites pretty much like the screenshots here. To achieve this with Interleaved Chronocolour , the background behind the fighters *HAS* to be solid black. The sprites can, however, go behind things so you could have a post or pole in front. But note, NO playfield modifications are possible where the sprites are being drawn, so you can't have a building in the background. Just vertical strips of things and a symmetrical playfield.

 

Cheers

A

[Robert M]

Hi Robert!

 

Look at Dolphin for proof of concept.   How did the programmer generate the Dolphin, Octopus, and Sea Weed without flicker?

 

You are fooled by Activision magic. The dolphin and the octopus are only one single sprite each. Take a careful look again. It's just clever shifting and double/quadruple sized pixels.

 

The only two possible Karateka approaches are either doing exact that (-> Double Dragon) or flicker (-> Fu Kung!)

 

Greetings,

Manuel

 

Manuel, I don't understand what you are saying here. I believe I made it clear that I plan to use "just clever shifting and double/quadruple sized pixels.". Also, I don't see any of that technique being used in Double Dragon, but then the only access I have to that title is the screen shots on this website.

 

Fu Kung is an awesome concept, but its not what I am looking for. I need the backgrounds to really capture the feel of the original game. Andrew's mega sprite technique requires a black background.

 

Cheers!

[Cybergoth]

Hi there!

 

Manuel, I don't understand what you are saying here.  I believe I made it clear that I plan to use "just clever shifting and double/quadruple sized pixels.".

 

Oh, I'm sorry. I just didn't read carefully enough and mix some things you said with some things others said.

 

Also, I don't see any of that technique being used in Double Dragon, but then the only access I have to that title is the screen shots on this website.

 

I thought when the DD players do "kicks", it's done by altering the NUSIZX values.

 

Greetings,

Manuel

[Robert M]

I have been thinking about this some more. I had planned originally to try and devise a sort of DMA controller in the cart to speed writes to the TIA, but then Paul suggested self modifing code. Looking at that possibility I could get 14 register writes per scanline plus an HMOVE. That would be enough for my purposes.

 

Therefore, I propose to put two 4K byte FIFOs into the cartridge. I will give these FIFOs each two 64 byte spaces in the memory map for reads, and writes will be mapped to somewhere in zero page. The program will push a frame worth of custom code into a FIFO. Then pass control to the head of the FIFO address space to draw the screen. The code for a scanline will execute, and then a JMP instruction will put control back at the start of the FIFO memory space for the next scanline. At the last scanline there will be a RTS instruction to pass control back to the main program.

 

Each FIFO has to regions in the memory map. Reading from one region empties the FIFO as each byte is read. Reading from the other 64 byte block will push the read byte back into the FIFO. This will allow the same code to be saved for display the following frame or be thrown away.

 

I figure it will take 2 to 3 frames to render a screen image into a FIFO. So the game would run at 20 or 30 Hz. That's okay since the action in Karateka is paced slower than most other games.

 

cheers!

[Cybergoth]

Hi Robert!

 

Since you are already so busy with Karateka, I assume Gravity Ball is now close to a release?

 

Greetings,

Manuel