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Made a first tentative attempt at supporting all eight sprite modes.

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This commit is contained in:
Thomas Harte
2015-07-30 11:52:28 -04:00
parent 151c6b4421
commit f653b5dff3
2 changed files with 63 additions and 33 deletions
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81
Machines/Atari2600.cpp
View File

@@ -31,18 +31,6 @@ Machine::~Machine()
void Machine::get_output_pixel(uint8_t *pixel, int offset)
{
// get the playfield pixel
const int x = offset >> 2;
const int mirrored = (x / 20) & (_playfieldControl&1);
const int index = mirrored ? x - 20 : 19 - (x%20);
const int byte = 2 - (index >> 3);
const int lowestBit = (byte&1)^1;
const int bit = (index & 7)^(lowestBit | (lowestBit << 1) | (lowestBit << 2));
// printf("%d -> %d -> %d -> %d/%d\n", offset, x, index, byte, bit);
uint8_t playFieldPixel = (_playfield[byte] >> bit)&1;
const uint8_t palette[16][3] =
{
{255, 255, 255}, {253, 250, 115}, {236, 199, 125}, {252, 187, 151},
@@ -59,23 +47,66 @@ void Machine::get_output_pixel(uint8_t *pixel, int offset)
69, 134, 108, 161, 186, 210, 235, 255
};
// get the playfield pixel
const int x = offset >> 2;
const int mirrored = (x / 20) & (_playfieldControl&1);
const int index = mirrored ? x - 20 : 19 - (x%20);
const int byte = 2 - (index >> 3);
const int lowestBit = (byte&1)^1;
const int bit = (index & 7)^(lowestBit | (lowestBit << 1) | (lowestBit << 2));
// printf("%d -> %d -> %d -> %d/%d\n", offset, x, index, byte, bit);
uint8_t playfieldPixel = (_playfield[byte] >> bit)&1;
// TODO: almost everything!
uint8_t playfieldColour = ((_playfieldControl&6) == 2) ? ((x < 20) ? _player0Colour : _player1Colour) : _playfieldColour;
uint8_t playfieldColour = ((_playfieldControl&6) == 2) ? _playerColour[x / 20] : _playfieldColour;
uint8_t playerPixels[2];
uint8_t outputColour = playFieldPixel ? playfieldColour : _backgroundColour;
if(!playFieldPixel || !(_playfieldControl&0x04))
for(int c = 0; c < 2; c++)
{
uint8_t playerOneBit = 0;
if(_horizontalTimer <= _playerPosition[0] && _horizontalTimer > _playerPosition[0] - 8) {
playerOneBit = _playerGraphics[0] >> ((_playerPosition[0] - _horizontalTimer) ^ ((_playerReflection[0]&0x8) ? 0 : 7));
if(playerOneBit&1) outputColour = _player0Colour;
int flipMask = (_playerReflection[c]&0x8) ? 7 : 0;
int relativeTimer = _playerPosition[c] - _horizontalTimer;
switch (_playerAndMissileSize[c]&7)
{
case 0: break;
case 1:
if (relativeTimer >= 16) relativeTimer -= 16;
break;
case 2:
if (relativeTimer >= 32) relativeTimer -= 32;
break;
case 3:
if (relativeTimer >= 32) relativeTimer -= 32;
else if (relativeTimer >= 16) relativeTimer -= 16;
break;
case 4:
if (relativeTimer >= 64) relativeTimer -= 64;
break;
case 5:
relativeTimer >>= 1;
break;
case 6:
if (relativeTimer >= 64) relativeTimer -= 64;
else if (relativeTimer >= 32) relativeTimer -= 32;
break;
case 7:
relativeTimer >>= 2;
break;
}
if(_horizontalTimer <= _playerPosition[1] && _horizontalTimer > _playerPosition[1] - 8) {
playerOneBit = _playerGraphics[1] >> ((_playerPosition[1] - _horizontalTimer) ^ ((_playerReflection[1]&0x8) ? 0 : 7));
if(playerOneBit&1) outputColour = _player1Colour;
if(relativeTimer < 8)
playerPixels[c] = (_playerGraphics[c] >> (relativeTimer ^ flipMask)) &1;
else
playerPixels[c] = 0;
}
uint8_t outputColour = playfieldPixel ? playfieldColour : _backgroundColour;
if(_playfieldControl&0x04 || !playfieldPixel) {
if (playerPixels[0]) outputColour = _playerColour[0];
if (playerPixels[1]) outputColour = _playerColour[1];
}
pixel[0] = palette[outputColour >> 4][0];
@@ -194,8 +225,8 @@ int Machine::perform_bus_operation(CPU6502::BusOperation operation, uint16_t add
case 0x04: _playerAndMissileSize[0] = *value; break;
case 0x05: _playerAndMissileSize[1] = *value; break;
case 0x06: _player0Colour = *value; break;
case 0x07: _player1Colour = *value; break;
case 0x06: _playerColour[0] = *value; break;
case 0x07: _playerColour[1] = *value; break;
case 0x08: _playfieldColour = *value; break;
case 0x09: _backgroundColour = *value; break;

3
Machines/Atari2600.hpp
View File

@@ -40,8 +40,7 @@ class Machine: public CPU6502::Processor<Machine> {
// graphics registers
uint8_t _playfield[3], _playfieldControl;
uint8_t _player0Colour;
uint8_t _player1Colour;
uint8_t _playerColour[2];
uint8_t _playfieldColour;
uint8_t _backgroundColour;
uint8_t _playerAndMissileSize[2];