diff options
Diffstat (limited to 'GPU2D.cpp')
| -rw-r--r-- | GPU2D.cpp | 38 |
1 files changed, 38 insertions, 0 deletions
@@ -22,6 +22,43 @@ #include "GPU.h" +// notes on color conversion +// +// * BLDCNT special effects are applied on 18bit colors +// -> layers are converted to 18bit before being composited +// * colors are converted as follows: 18bit = 15bit * 2 +// -> white comes out as 62,62,62 and not 63,63,63 +// * VRAM/FIFO display modes convert colors the same way +// * 3D engine converts colors differently (18bit = 15bit * 2 + 1, except 0 = 0) +// * 'screen disabled' white is 63,63,63 +// +// oh also, changing DISPCNT bit16-17 midframe doesn't work (ignored? applied for next frame?) +// TODO, eventually: check whether other DISPCNT bits can be changed midframe +// +// sprite blending rules +// * destination must be selected as 2nd target +// * sprite must be semitransparent or bitmap sprite +// * blending is applied instead of the selected color effect, even if it is 'none'. +// * for bitmap sprites: EVA = alpha+1, EVB = 16-EVA +// * for bitmap sprites: alpha=0 is always transparent, even if blending doesn't apply +// +// 3D blending rules +// +// 3D/3D blending seems to follow these equations: +// dstColor = srcColor*srcAlpha + dstColor*(1-srcAlpha) +// dstAlpha = max(srcAlpha, dstAlpha) +// blending isn't applied if dstAlpha is zero. +// +// 3D/2D blending rules +// * if destination selected as 2nd target: +// blending is applied instead of the selected color effect, using full 31bit alpha from 3D layer +// this even if the selected color effect is 'none'. +// apparently this works even if BG0 isn't selected as 1st target +// * if BG0 is selected as 1st target, destination not selected as 2nd target: +// brightness up/down effect is applied if selected. if blending is selected, it doesn't apply. +// * 3D layer pixels with alpha=0 are always transparent. + + GPU2D::GPU2D(u32 num) { Num = num; @@ -49,6 +86,7 @@ void GPU2D::SetFramebuffer(u16* buf) { // framebuffer is 256x192 16bit. // might eventually support other framebuffer types/sizes + // TODO: change this. the DS uses 18bit color Framebuffer = buf; } |