VDP2 cache progress

The cache is finally working for the VDP2 cell mode (the one used in the bios). I had some transparency problem due to textures not being reloaded when the transparency bit of the screen was changed, but that’s now corrected.
Performances are quite interesting in the current cache state, ie around 50 fps when the “Sega Saturn” text is displayed, and between 30 and 40 fps inside the cd player.

You might say it’s not that fast, but actually as the whole page is displayed (ie 512*512 pixels) instead of just the visible part (ie 320*224 in that case), a lot of extra calculation is done, which slows down the display. Of course I’ll change that in the future, but right now it’s already faster than it was in the previous release, so that’s a good start 🙂

Now that’s the cache is running for cell mode, I’m now in the process of integrating bitmap mode to it … I took the opportunity to redesign the way both modes are setup, and to put it in different functions.
My goal is to have the whole bitmap to be added as a single texture to the texture map. That implies to modify the texture class structure, as until now each VDP2 texture was considered to be 8*8.

Now the bitmap texture will just be considered as a big cell (up to 1024*512), and displayed like the others.

So what are the next steps ?

  • add bitmaps to the VDP2 cache
  • convert the other display modes to use the cache
  • test the cache speed, and improve it

That’s all for now (but that’s a lot, believe me :p)

One Response to VDP2 cache progress

  1. Avatar El Siskoo
    El Siskoo says:

    Keep up the good work…