Randomize virtual player colors in DPC+?

[jrok]

I've noticed it's fairly straightforward to randomize P0's colors with the statement:

player0color = rand

 

Is there a similarly simple method of assigning random colors to a virtual player?

 

Thanks,

J

Edited May 13, 2016 by jrok

[RevEng]

It's not as simple with DPC+. DPC+ maintains ARM memory pointers to virtual player's color, so you need to call a DPC+ function to update these pointer values.

 

For player1color: it would look like...

 

 asm
 lda #<(playerpointers+18)
 sta DF0LOW
 lda #(>(playerpointers+18)) & $0F
 sta DF0HI
 LDX rand
 STX DF0WRITE
 LDA #0
 STA DF0WRITE
end

For player2colors change the 18's to 20's. For player3colors: change the 18's to 22's. Keep adding +2 for later colors.

[jrok]

Thank you!

[jrok]

I have related question:

 

Suppose I wanted to do the following:

 

- Define the colors for each line of a virtual sprite (in a data statement, I'm guessing? Then push them into the sprite?)

- Add a multiple of 16 to each line when the code is run.

 

I'm trying to build a palette swapping function, preserving each line's brightness while shifting the hue.

 

Thanks again.

[RevEng]

Ok, so I dug into this a bit more and refreshed myself on the details... I've updated my previous explanation as a result, but the code I gave earlier still holds.

 

Changing the hue values isn't going to happen easily. When you use player#colors: with DPC+, the color values are stored in "ROM" same as with other kernels. bB then sets up the ARM player#color pointers to point to where that ROM color data appears in ARM memory.

 

Since it's all in ROM, you'd first need to change that ARM pointer to point to ARM RAM instead, so you can modify the contents. I tried pointing it to the bB DPC+ stack page, but that didn't seem to work correctly.

 

I'm sure I'm missing some ARM pointer implementation detail, but I've reached the limit of my knowledge here.

[jrok]

No worries. Just in case I wasn't explaining myself right, I wrote a little test program a while back that does a similar color swap with the playfield object.

set kernel DPC+

dim PF_line = a

dim chroma = b

dim chroma_shift = c

goto Start bank2

bank 2

Start

playfield:

..............XXX...............

.............XXXXX..............

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..............XXX...............

end

data zonelumshift

$00,$00,$02,$02,$04,$06,$08,$0A,$0C,$0E,

$00,$00,$00,$02,$02,$02,$04,$04,$04,$06,

$02,$02,$04,$04,$02,$02,$04,$04,$02,$02,

$00,$02,$04,$06,$08,$08,$06,$04,$02,$00,

$00,$02,$00,$04,$00,$06,$00,$08,$00,$0A

end

chroma = 16

WritePFColorLoop

DF0FRACINC=128

DF1FRACINC=128

DF2FRACINC=128

DF3FRACINC=128

DF4FRACINC=128

DF6FRACINC=128

DF7HI = 10

DF7LOW = 52

PFColor

for temp1 = 0 to zonelumshift_length

DF7PUSH = zonelumshift[PF_line] + chroma

PF_line = PF_line + 1

next

PF_line = 0

rem Press and release the fire button to change the color

if joy0fire then chroma_shift = 1

if !joy0fire && chroma_shift then chroma_shift = 0 : chroma = chroma + 16

drawscreen

goto WritePFColorLoop

It's been a couple of years since I've tucked into bB, and I forget how I determined the hi and lo pointers for the playfield. I assume I could use a similar technique to color the background, right?

Edited May 17, 2016 by jrok

[RevEng]

I assume I could use a similar technique to color the background, right?

Sort of confused if we're talking about sprite colors or background playfield colors. Your earlier post talked about sprite colors, here you mention background [playfield] colors.

 

bB DPC+ playfields (and colors) are RAM based, and can be modified, swapped, etc. bB DPC+ players (and colors) are pointers to ROM, which can't be modified. (in theory, you can point them to RAM, and modify the RAM, but I can't get this to work.)

 

If you wish to modify the PF background color, change the "DF7HI" index to point to another queue/page in your example. IIRC, it's probably 11 for background colors. The "DF7LOW" value is the byte offset within the playfield data.

[jrok]

Sort of confused if we're talking about sprite colors or background playfield colors. Your earlier post talked about sprite colors, here you mention background [playfield] colors.

 

bB DPC+ playfields (and colors) are RAM based, and can be modified, swapped, etc. bB DPC+ players (and colors) are pointers to ROM, which can't be modified. (in theory, you can point them to RAM, and modify the RAM, but I can't get this to work.).

 

Sorry, I drifted off topic there. Yeah, that was the original question, I just included that sample in case I wasn't explaining the desired (sprite) effect well enough.

 

 

If you wish to modify the PF background color, change the "DF7HI" index to point to another queue/page in your example. IIRC, it's probably 11 for background colors...

 

 

Yes, it is. I tried to RTFM for this, but I couldn't find it documented anywhere. Thanks, again.

[RevEng]

No worries. Glad to help!

[Lillapojkenpåön]

I've been playing around with changing the pf and bgcolors for a couple days and came up with a really cool thing for my game but now that I got a chance to try it on real hardware it doesn't change anything, so I tried jrok's code and it works in stella but just boots a black screen on real hardware (mine atleast)

 

Here's my little test that does boot up but doesn't change anything like it does in stella, Something wrong with my code? like byte offset (I used the d variable to pick those numbers) or has this never worked on real hardware?

 

colorchange.bas

[Lillapojkenpåön]

I really need some help with my question above.

[+Karl G]

At least as a starting point, your playfield definition is messed up. It is inconsistently indented (which makes it hard to read), some lines are not indented at all (everything other than the "end" statement needs to be indented by at least once character), and some lines are the wrong length (all of them should be 32 characters).

[Lillapojkenpåön]

Ok I fixed that, and changed every temp variables to regular ones, moved some stuff around and tried different things until I thought it could only be the value for DF7LOW that's wrong, so I changed it to a counter and thought it must hit the right number some time and have some effect? So right now in stella the pf and bgcolors scrolls and you can change colors with the fire button, but on real hardware it has no effect..

 

 

d=d+1 ;df7low counter

if joy0fire then chroma = chroma + 16

DF7HI = 10

DF7LOW = d

;.............................rails

PF_line = 0

PFColor

for e = 1 to 9

DF7PUSH = zonelumshift[PF_line] + chroma

PF_line = PF_line + 1

next

;...........................top wall

PF_line = 0

DF7HI = 11

DF7LOW = d

for e = 1 to 10

DF7PUSH = zonelumshift3[PF_line] + chroma

PF_line = PF_line + 1

next

;...........................bottom wall

PF_line = 0

DF7HI = 11

DF7LOW = d

for e = 1 to 10

DF7PUSH = zonelumshift2[PF_line] + chroma

PF_line = PF_line + 1

next

Just a normal display of the colors in the initialization????

colorchange (2).bas

Edited May 2, 2018 by Lillapojkenpåön

[Lillapojkenpåön]

Got it to work

 

colorchange (5).bas

[Lillapojkenpåön]

I have a related question..

Does storing values to DF0HI, DF0LOW and DF0PUSH take alot of cycles similar to using the stack?