Hardware Accelerated Mouse Pointer (a.k.a. Sprite)

Posted by Hans de Ruiter

The mouse pointer now uses the Radeon card's sprite hardware. The graphics card documentation calls it "Cursor," which matches the X-windows terminology. This was a fairly straightforward task, with just a few issues such as ARGB vs. RGBA pixel formats, and alpha-channel blending modes. 

Previously Picasso96 (Amiga OS 4.x's retargetable graphics system) used a "soft-sprite," which is another way of saying that it had to render the mouse pointer over the top of the main image itself. Moving a hardware sprite, on the other hand only requires telling the hardware where to put it; compositing is handled by the graphics card.

Now that the mouse pointer is hardware accelerated, my eyes are firmly set upon hardware accelerated BLock Image Transfer (BLIT) operations, a.k.a. blitter operations. At this point the code will become chipset specific, since the command processors that handles any rendering operations is unique to each chipset series (i.e., R5xx chipsets work differently from the R6xx series). Up to now, the AtomBIOS hid most of the differences between chipsets, but this is for framebuffer operations only. The sprite hardware is also common between the chipsets.

Comments (4) | 8 February 2009