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DrawPixel refactoring to avoid doubled up conditions, etc.

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This commit is contained in:
Souryo 2014-06-28 22:52:28 -04:00
parent f8ecd1be5e
commit 0636b52ad1
1 changed files with 16 additions and 26 deletions
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42
Core/PPU.cpp
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@ -396,12 +396,14 @@ void PPU::DrawPixel()
uint32_t backgroundColor = 0; uint32_t backgroundColor = 0;
uint32_t spriteColor = 0; uint32_t spriteColor = 0;
if(_flags.BackgroundEnabled) { if((_cycle > 8 || _flags.BackgroundMask) && _flags.BackgroundEnabled) {
//BackgroundMask = false: Hide background in leftmost 8 pixels of screen
backgroundColor = (((_state.LowBitShift << offset) & 0x8000) >> 15) | (((_state.HighBitShift << offset) & 0x8000) >> 14); backgroundColor = (((_state.LowBitShift << offset) & 0x8000) >> 15) | (((_state.HighBitShift << offset) & 0x8000) >> 14);
} }
uint8_t i; uint8_t i;
if(_flags.SpritesEnabled) { if((_cycle > 8 || _flags.SpriteMask) && _flags.SpritesEnabled) {
//SpriteMask = true: Hide sprites in leftmost 8 pixels of screen
for(i = 0; i < _spriteCount; i++) { for(i = 0; i < _spriteCount; i++) {
int32_t shift = -((int32_t)_spriteX[i] - (int32_t)_cycle + 1); int32_t shift = -((int32_t)_spriteX[i] - (int32_t)_cycle + 1);
if(shift >= 0 && shift < 8) { if(shift >= 0 && shift < 8) {
@ -413,36 +415,24 @@ void PPU::DrawPixel()
if(spriteColor != 0) { if(spriteColor != 0) {
//First sprite without a 00 color, use it. //First sprite without a 00 color, use it.
if(backgroundColor == 0 || !_spriteTiles[i].BackgroundPriority) {
//Check sprite priority
useBackground = false;
}
if(i == 0 && backgroundColor != 0 && _sprite0Visible && _cycle != 256 && _flags.BackgroundEnabled) {
//"The hit condition is basically sprite zero is in range AND the first sprite output unit is outputting a non-zero pixel AND the background drawing unit is outputting a non-zero pixel."
//"Sprite zero hits do not register at x=255" (cycle 256)
//"... provided that background and sprite rendering are both enabled"
//"Should always miss when Y >= 239"
_statusFlags.Sprite0Hit = true;
}
break; break;
} }
} }
} }
} }
if(_cycle <= 8) {
if(!_flags.BackgroundMask) {
//"0: Hide background in leftmost 8 pixels of screen;"
backgroundColor = 0;
}
if(!_flags.SpriteMask) {
//"0: Hide sprites in leftmost 8 pixels of screen;"
spriteColor = 0;
}
}
if(spriteColor != 0 && (backgroundColor == 0 || !_spriteTiles[i].BackgroundPriority)) {
//Check sprite priority
useBackground = false;
}
if(i == 0 && spriteColor != 0 && backgroundColor != 0 && _sprite0Visible && _cycle != 256 && _flags.BackgroundEnabled && _flags.SpritesEnabled) {
//"The hit condition is basically sprite zero is in range AND the first sprite output unit is outputting a non-zero pixel AND the background drawing unit is outputting a non-zero pixel."
//"Sprite zero hits do not register at x=255" (cycle 256)
//"... provided that background and sprite rendering are both enabled"
//"Should always miss when Y >= 239"
_statusFlags.Sprite0Hit = true;
}
uint32_t bufferPosition = _scanline * 256 + (_cycle - 1); uint32_t bufferPosition = _scanline * 256 + (_cycle - 1);
if(useBackground) { if(useBackground) {
// If we're grabbing the pixel from the high part of the shift register, use the previous tile's palette, not the current one // If we're grabbing the pixel from the high part of the shift register, use the previous tile's palette, not the current one