you explanation is right. I programmed my own version of this sinuscroller after i watched how he had programmed it in my action replay, but i couldn't make it as fast as he did. i couldn't add any music :( . The bar who is in 3 pitplanes(bpl) he putted on even bpl and let the copper scroll for him. The char scroller is in 2 bpl and is on bpl 1,3. the rotation of the chars is precalculated animation. He let the blitter copy the chars form a workbench in chip memory to the screen.
If i don't remember wrong this tune is only in 3 channels because he had no Cpu left for 4 channels. It's hardly Photon manage to make this full screen sinus intro with music. I bet he would have added stars in the background if there were time left for Cpu to draw it.
Very nice effect. I don't know how it was done but I'd like to guess...
If you ignore the red bar, the rotating scroller seems an easier problem. Create a flat 16x16 scroller in memory with 16 blank rasters above and below. You can blit from this buffer at different vertical offsets to create that rotating effect. Using two bitplanes (one for the front and one for the back) means that this will use up most of the raster time on a 500...
After that, you just need to add the red bar. Fortunately it doesn't need to be sine-scrolled. Once the sine has been created in memory, just horizontal hardware scrolling is enough. If you aren't convinced, try imagining just the bar without the text overlay...
So apart from the cycles consumed by the video DMA, it can be done in virtually zero raster time.
you explanation is right. I programmed my own version of this sinuscroller after i watched how he had programmed it in my action replay, but i couldn't make it as fast as he did. i couldn't add any music :( . The bar who is in 3 pitplanes(bpl) he putted on even bpl and let the copper scroll for him. The char scroller is in 2 bpl and is on bpl 1,3. the rotation of the chars is precalculated animation. He let the blitter copy the chars form a workbench in chip memory to the screen.
skipper7302 3 years ago
Yep, understanding the trick is just the first stage. Implementing it efficiently is another challenge. :)
kojiki1976 3 years ago
If i don't remember wrong this tune is only in 3 channels because he had no Cpu left for 4 channels. It's hardly Photon manage to make this full screen sinus intro with music. I bet he would have added stars in the background if there were time left for Cpu to draw it.
skipper7302 3 years ago
Very nice effect. I don't know how it was done but I'd like to guess...
If you ignore the red bar, the rotating scroller seems an easier problem. Create a flat 16x16 scroller in memory with 16 blank rasters above and below. You can blit from this buffer at different vertical offsets to create that rotating effect. Using two bitplanes (one for the front and one for the back) means that this will use up most of the raster time on a 500...
kojiki1976 3 years ago
After that, you just need to add the red bar. Fortunately it doesn't need to be sine-scrolled. Once the sine has been created in memory, just horizontal hardware scrolling is enough. If you aren't convinced, try imagining just the bar without the text overlay...
So apart from the cycles consumed by the video DMA, it can be done in virtually zero raster time.
kojiki1976 3 years ago
I don't know if my explanation is right. If anyone knows better, please tell me!
Anyway, kudos to Photon. This is an original and unique demo.
kojiki1976 3 years ago
But he didn't copy the 2pbl char scroller from a flat scroller.
skipper7302 3 years ago