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PPU: Fixed negative X sprite display logic

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This commit is contained in:
Sour 2019-02-24 13:09:22 -05:00
parent 66cc7847fb
commit 5a45665d74
1 changed files with 11 additions and 12 deletions
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23
Core/Ppu.cpp
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@ -146,9 +146,15 @@ void Ppu::EvaluateNextLineSprites()
SpriteInfo &info = _sprites[_spriteCount];
info.LargeSprite = largeSprite;
uint8_t width = _oamSizes[_oamMode][info.LargeSprite][0] << 3;
uint16_t sign = (highTableValue & 0x01) << 8;
info.X = (int16_t)((sign | _oamRam[i]) << 7) >> 7;
if(info.X != -256 && info.X + width <= 0 || info.X > 255) {
//Sprite is not visible (and must be ignored for time/range flag calculations)
//Sprites at X=-256 are always used when considering Time/Range flag calculations, but not actually drawn.
continue;
}
bool negativeX = (highTableValue & 0x01) != 0;
info.X = negativeX ? -_oamRam[i] : _oamRam[i];
info.TileRow = (_oamRam[i + 2] & 0xF0) >> 4;
info.TileColumn = _oamRam[i + 2] & 0x0F;
@ -170,9 +176,7 @@ void Ppu::EvaluateNextLineSprites()
}
uint8_t row = (info.TileRow + rowOffset) & 0x0F;
constexpr uint16_t bpp = 4;
for(int x = info.X; x > 0 && x < info.X + width && x < 256; x++) {
for(int x = std::max<int16_t>(info.X, 0); x < info.X + width && x < 256; x++) {
if(_spritePixels[x] == 0xFFFF) {
uint8_t xOffset;
int columnOffset;
@ -188,15 +192,10 @@ void Ppu::EvaluateNextLineSprites()
uint8_t tileIndex = (row << 4) | column;
uint16_t tileStart = ((_oamBaseAddress + (tileIndex << 4) + (info.UseSecondTable ? _oamAddressOffset : 0)) & 0x7FFF) << 1;
uint16_t color = 0;
for(int plane = 0; plane < bpp; plane++) {
uint8_t offset = (plane >> 1) * 16;
uint8_t tileData = _vram[tileStart + yOffset * 2 + offset + (plane & 0x01)];
color |= ((tileData >> (7 - xOffset)) & 0x01) << plane;
}
uint16_t color = GetTilePixelColor<4>(tileStart + yOffset * 2, 7 - xOffset);
if(color != 0) {
uint16_t paletteRamOffset = 256 + ((info.Palette * (1 << bpp) + color) * 2);
uint16_t paletteRamOffset = 256 + (((info.Palette << 4) + color) << 1);
_spritePixels[x] = _cgram[paletteRamOffset] | (_cgram[paletteRamOffset + 1] << 8);
_spritePriority[x] = info.Priority;
_spritePalette[x] = info.Palette;