Hello, I am starting with the ti84 pce, not really much experience in z80 assembly, but understand the basics.

I wrote a simple ball bouncing program to get myself started. Writing/Erasing the sprite directly on the vRAM is pretty fast (both in 16bpp and 8bpp) but results in some flickering as the ball moves across the screen. I then tried double buffering (with 8bpp) but I am still getting some flickering and much reduced speed. I was wondering if there is any good tutorial/info on changing the LCD base instead of copying the whole buffer that seems to slow down the code.

I think Mateo posted something on that but a more detailed explanation will be appreciated.

Thanks in advance!

The CE LCD has a flag that is set when a new address is able to be loaded into the LCD base address. This is enabled using the following code:


Code:


Then when you want to swap the pointers, simply call this function:


Code:


currDrawBuffer is used to specify which buffer you are drawing to, so use it as the base drawing offset

Thanks a lot Mateo!

I was wondering if the code for enabling the interrupt should be (in the first code fragment of your reply)
ld l, mpLcdImsc&$ff
instead of
ld l, mpLcdIcr&$ff

Anyway, I see that clearing & waiting for the interrupt makes the code way slower. Was that your experience as well?

I am currently swapping the two buffers by changing the mpLcdBase manually after finishing drawing in the buffer that is currently not displaying. This results in a pretty fast code with minimal visual artefacts.

It may be of course that I am missing something

Hello,

Based on Mateo's comment above, my current implementation for page-flipping is shown below (pseudocode with some Z80 assembly)


Code:


Please feel free to comment and improve!

Thanks

PS: An interesting article on double-buffering and page-flipping can be found at https://docs.oracle.com/javase/tutorial/extra/fullscreen/doublebuf.html

I probably dont know what im talking about, but i am pretty sure the CE is ez80, not z80 (dont know if that changes anything)

Yep, that's basically it, although don't forget to erase the buffer before drawing to it

(Also, I prefer writing numbers as a logical expression. 76800 doesn't make sense to a beginner, while 320*240 does )

Thanks guys.

I agree Pienman7373, should had put down eZ80, not Z80 in my post

Thanks for the tip PT, 320*240 clearly makes more sense than 76800. Also I do erase the back buffer, but you are right I should had clarified this in the pseudocode above.

Also, in many programs, you see like LCD_WIDTH * LCD_HEIGHT which makes even more sense