Colours, priorities and colisions - 2 questions

[José Pereira]

I wake up this morning with this on my head. I think it´s not silly, but someone will have the answers...

 

 

- 1st QUESTION: PM0 overlap with PF0/1 you get 2 new colours (PM0/PF0 overlap colour and PM0/PF1 overlap colour).

Now, as an example, your player it´s PF0 (a software sprite). And the question is: If the software sprite pass over PM0/PF0 overlap colour, what colour he gets in that area?

 

 

- 2nd QUESTION: PM0 overlap with PF0/1 like above. You get 2 new colours. About colision registers, this 2 new colour cells, are what (PF0, PF1, PM0, new...)?

 

 

THANKS FOR YOUR HELP.

José Pereira.

[Rybags]

1. Playfield can't overlap playfield.

 

2. Collisions still register the same - the actual "colour" doesn't make any difference. Of course, you'll typically get multiple collision instances e.g. if Player 2 was overlapping a pixel of PF0 that was altered by Player 1.

[MaPa]

1 - your soft sprite can't go over PF0, the sprite IS PF0 itself (in your example), so everywhere where PM0/1 overlaps your PF0 soft sprite, it will change it's colour unless you clear PM data in the overlap region.

 

2 - collision registers doesn't care about colours displayed on screen, they just register collision between "objects" (playfield and pmg). The 2 new colour cells are just PF0 in collision with PM0 and PF1 in collision with PM0 IMHO

 

Edit: Rybags was faster

Edited June 8, 2009 by MaPa

[Jetboot Jack]

I have a related question - if you generate extra colors with these GPRIOR techniques - can you get priority control to allow play field to appear above sprites in priority - so certain PF registers mask the sprites - stencil style for increased PMG resolution?

[Rybags]

You're kinda stuck with what it gives you with the ORed interaction betweeen PMs and Playfield (disregarding stuff like changing PRIOR on the fly), since you have to set the low 4 bits to zero to achieve the effect.

 

Of course, you're free to do whatever you want so far as choosing whether the PMG pairs operate in multicolour mode or if the missiles take PF3s colour.

[Jetboot Jack]

Thanks Rybags I understand now

 

I also found an image from NRV that shows the priorities in action, which I pasted into this thread - NRV's 23 color image

 

sTeVE