Preppie

I'm an atari800 guy so don't normaly come in this part of the forum, but just thought I'd post this link in case anyone isn't sub'd to this great channel:

And his new one is done with character mode:

If you like that, this will blow you away

You only need to be able to draw the top line. If you look at the video carefully you see the top line is mainly grey with an occasional black pixel. Once the fill is used that line becomes a wall with black edges. If you want to know how to draw the top line then that's a bit of trigonometry.

Here's a video of capture the flag with the fill removed. As you can see, only the top edge of the maze walls are drawn, they are then reflected by the display list to the bottom. CTF also uses a different graphics mode on the bottom half of screen to create a different perspective. All that needs to be done now is for the XOR fill to do it's work on the top half of screen and that will be reflected to the bottom. Thanks to Heaven/TQ for his orginal post

Go back and read this post: As he said, you draw the top edges of a wall and then use an XOR fill. So if the first column of bytes in the screen was: byte $00 = 00000000 byte $28 = 11000000 byte $50 = 00110000 byte $78 = 00001100 byte $A0 = 00000010 byte $CB = 00000000 byte $F0 = 00000000 You would XOR bytes $00 and $28 and store in byte $28 Then XOR bytes $28 and $50 and store in $50 etc. Results: byte $00 = 00000000 byte $28 = 11000000 byte $50 = 11110000 byte $78 = 11111100 byte $A0 = 11111110 byte $CB = 11111110 byte $F0 = 11111110 As a maze is vertically symetrical you only need to draw the top half and then use a custom display list to mirror the top half to the bottom.

Thorfdbg already explained this, you even quoted his explanation - so we know it's not raycast

I think the games should be made to work as well as possible on real machines. No one expects emulation to be perfect, and reloading a game after an emulator change takes 2 secs.

Rainbow Walker always impressed me.

yep it's a fairly short routine and leaves PMs available for other stuff.

The description of how wayout creates the screen got my gears turning so I threw together a little demo in FastBasic. First one is all FastBasic, second has had the exor fill routine replaced with a bit of assembly. The display list is 30x mode 7 36 lines that copy line 30 30 lines that reflect the top 30 (line37 is 30, 38 is 29, 39 is a copy of 28 etc.) Just need to draw the top lines and the fill and DL do the rest. The garbled screen at the start is the 2 display lists for page flipping the screen. Both DLs and both screens fit into the area of standard gr.7 memory I think I may have my next 10 liner in the works

A mate needed a MB/memory/GFX card upgrade doing, not a hard job but he gave me his old GTX1050TI as payment. , Given the silly prices of cards these days I was considering selling the thing and continuing to use a quadro K620 I grabbed cheap on ebay (actual a very nice low end card for the price(£22), about gt1030 power) but decided to keep it and put the quadro in daughters pc. My mug just says 'worlds greatest dad' - not very original but true

There's a number of videos about raycasting on youtube, one of the better ones I've found is: And OLC is always good to watch, whatever he's doing.

That's a nifty little trick there.

Goto atarimania.com under the utilities tab and search http://www.atarimania.com/list_utilities_atari_search_97.110.116.105.99._8_U.html