Saturday, December 31, 2005

OAM (t.a.g.)

You already know sprites are movable images that can be freely placed over the background image in a computer game. Now that you've read all of the OAM tags, you also know that a sprite as we see it in-game is often built of multiple hardware sprites which usually have quite restricted size (e.g. 8x{8; 16} for NES, 8x8 to 64x64 for DS, but not e.g. 24x16).

VRAM alone doesn't make a sprite.
Each hardware sprite is controlled by an entry in the graphic chip's descriptors, giving its position and other attributes (like flipping bits) and that completes the sprite tiles storage (spritesheet) in either ROM or video RAM.

On the nintendo consoles, these are named Object Attribute Memory entries. I use that 'OAM' term when I truly mean "a hardware sprite", not a Game Object's rendition on screen (sprite).

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