Atari Graphics Fun Question

[atarilux]

Hello,

 

I have been playing around mainly with FastBasic and some limited assembler (mainly WUSDN tutorials). I have had some success playing with display lists, so excuse the  perhaps silly question. So far all the demos I've seen only use the display list to change the background colour, and not any of the foreground colors (to increase the overall number of screen colours). The only way I can see to get potentially may colours "on screen" is to use page flipping, or have I misunderstood how display lists (interrupts) work? 

 

I am mainly using Antic Mode 4 with character set mods to achieve the results on screen. Ideally, having more colours via changing what is available on a (character) line by line basis. The machine being used is a stock 800XL, so no fancy mods!

 

All other aspects seem quite straight forward e.g. sprites. So thanks to the many excellent pages online including Atariprojects etc.

 

A (for now) still a newbie

[popmilo]

Interrupts just run piece of code that can do many different things.
Nothing is stopping you from changing any of color registers. You can change colpf0-3, colbk, pm 0-3 colors, player xpositions, character set chbase etc...

 

[TGB1718]

You can even have a DLI that runs different code depending on which line your on, the only limit

of DLI's is they have to be very short otherwise you get undesired effects on screen.

[zzip]

1 hour ago, atarilux said:

Hello,

 

I have been playing around mainly with FastBasic and some limited assembler (mainly WUSDN tutorials). I have had some success playing with display lists, so excuse the  perhaps silly question. So far all the demos I've seen only use the display list to change the background colour, and not any of the foreground colors (to increase the overall number of screen colours). The only way I can see to get potentially may colours "on screen" is to use page flipping, or have I misunderstood how display lists (interrupts) work? 

 

I am mainly using Antic Mode 4 with character set mods to achieve the results on screen. Ideally, having more colours via changing what is available on a (character) line by line basis. The machine being used is a stock 800XL, so no fancy mods!

 

All other aspects seem quite straight forward e.g. sprites. So thanks to the many excellent pages online including Atariprojects etc.

 

A (for now) still a newbie

You can change any or all of the color registers in a DLI, this is the most common technique to increase the on-screen colors   

 

You could also do stuff like change the horizontal position of a Player sprite in a DLI, which effectively can create two sprites with different positions on the top and bottom of the screen

[TGB1718]

Have a look at this, was just something I wrote to see how many players I could get on screen at one time

let it run for a bit and you can see they separate, change colour and position.

 

I used a VBI to calculate the the player positions, then used a multi-dli to position the sprites and change the colours.

PLAYER.XEX

[Preppie]

If your using FastBasic you can use the DLI command to setup display list interupts instead of writing your own assembly routines.

 

Also, there's a great DLI tutorial here https://playermissile.com/dli_tutorial/

[atarilux]

On 7/13/2021 at 3:38 PM, TGB1718 said:

Have a look at this, was just something I wrote to see how many players I could get on screen at one time

let it run for a bit and you can see they separate, change colour and position.

 

I used a VBI to calculate the the player positions, then used a multi-dli to position the sprites and change the colours.

PLAYER.XEX 1.82 kB · 20 downloads

 

Thanks for this demo. It is impressive to see so many players with so much color. Also, the frame rate remains high. I shall have to figure out how to do similar things myself.