Miscellaneous questions about coding techniques

[Mark2008]

OK, for some odd reason I find that deferred vblank never works for me in KickC.

And yet I used deferred VBlank without issue in CC65.

 

I know I'm just doing something wrong, so....I spy a little command called SEI()

I didn't write that command, I copied it, and each project it keeps getting copied.  Does that disable deferred vblank?

 

OK, just wanted to ask that, but it isn't the main question.

 

The main question today is, I've got an animation I want to do, it is a type of 3d perspective.

Lets say you are looking out a passenger window at roads you are passing, whereby the  appear angled to the right, until you are just on them, and then it appears perpendicular, and then it appears angled left after you passed it...I'm going for this type of effect.

I can post a video, if that doesn't explain it, but anyway - some fun animation is the idea.

 

This game is currently in Antic E.  The area to animate is about 40 lines.  The animation sequence would take 35s.

 

So 35s * 15 frames/sec * 40 bytes/line * 40 lines = 840,000 bytes.

 

Too much?  Ok too much.   I wanted to first see if I could just store the entire animation uncompressed in memory and twiddle LMS instructions in the display list, to point to different areas of memory, because it'd take almost no CPU horsepower and the main thing I wouldn't have to think about it.

 

OK, but another approach might be compress the animation and use vblank to uncompress.  Event still, each frame would be 40 * 40 or 1600 bytes.  In that strategy, I could probably get 1600 bytes written to a screen memory during vblank.  Because my animation is only 2 colors of the potential four plus for other reasons related to having a lot of space and repetition, I could get great compression.  But even if it were 10%, it's still be an absurd 84K.

 

So, is it really the case, that's just not how you do animations?  I have to think in terms of plotting lines and doing fills?   

 

Let me know if I didn't explain it.....I just want a feel from the experienced coders on how you accomplish such things.

 

 

[Rybags]

Remember Cyber Paint on the ST?

It could do animation sequences - the compression used was a mix of RLE and XOR of the data that had to change.  For something that's moving a little bit per frame it can be a pretty efficient method.  I don't know if there's been any use of it or examples available on the 8-bit though.

[Mark2008]

thanks. Iwill check it out.  

 

I think I’ve wrapped my head around an idea, which if course I dont think of until after asking the question.    choplifter does this type of perspective animation just after leaving the helipad, with larger faster bridge pieces in front with smaller, slower ones in the back.  i was thinking that is cool image trick but now that I think about it it would work for line art. 

 

i may just need custom rle for this specific task... well i will know soon