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Continuing in my attempts to figure out the complete absence of graphics from some games: there are 262 lines on an NTSC screen, not 256. Also ensured that the CRT has a little spare range at the edges so that its generated triangles don't wrap around just because of integer overflow.

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This commit is contained in:
Thomas Harte 2015-07-30 20:07:20 -04:00
parent 98efae2536
commit 1fa7a77793
2 changed files with 24 additions and 22 deletions
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6
Machines/Atari2600.cpp
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@ -19,7 +19,7 @@ Machine::Machine()
_horizontalTimer = 227;
_lastOutputStateDuration = 0;
_lastOutputState = OutputState::Sync;
_crt = new Outputs::CRT(228, 256, 1, 4);
_crt = new Outputs::CRT(228, 262, 1, 4);
_piaTimerStatus = 0xff;
reset();
@ -105,9 +105,9 @@ void Machine::get_output_pixel(uint8_t *pixel, int offset)
uint8_t outputColour = playfieldPixel ? playfieldColour : _backgroundColour;
if(_playfieldControl&0x04 || !playfieldPixel) {
if (playerPixels[0]) outputColour = _playerColour[0];
if(!(_playfieldControl&0x04) || !playfieldPixel) {
if (playerPixels[1]) outputColour = _playerColour[1];
if (playerPixels[0]) outputColour = _playerColour[0];
}
pixel[0] = palette[outputColour >> 4][0];

40
Outputs/CRT.cpp
View File

@ -12,6 +12,9 @@
using namespace Outputs;
static const uint32_t kCRTFixedPointRange = 0xefffffff;
static const uint32_t kCRTFixedPointOffset = 0x08000000;
#define kRetraceXMask 0x01
#define kRetraceYMask 0x02
@ -35,10 +38,10 @@ CRT::CRT(int cycles_per_line, int height_of_display, int number_of_buffers, ...)
_horizontal_retrace_time = (millisecondsHorizontalRetraceTime * _cycles_per_line) >> 6;
_vertical_retrace_time = scanlinesVerticalRetraceTime * _cycles_per_line;
_scanSpeed.x = UINT32_MAX / _cycles_per_line;
_scanSpeed.y = UINT32_MAX / (_height_of_display * _cycles_per_line);
_retraceSpeed.x = UINT32_MAX / _horizontal_retrace_time;
_retraceSpeed.y = UINT32_MAX / _vertical_retrace_time;
_scanSpeed.x = kCRTFixedPointRange / _cycles_per_line;
_scanSpeed.y = kCRTFixedPointRange / (_height_of_display * _cycles_per_line);
_retraceSpeed.x = kCRTFixedPointRange / _horizontal_retrace_time;
_retraceSpeed.y = kCRTFixedPointRange / _vertical_retrace_time;
// precompute the lengths of all four combinations of scan direction, for fast triangle
// strip generation later
@ -56,8 +59,8 @@ CRT::CRT(int cycles_per_line, int height_of_display, int number_of_buffers, ...)
// width should be 1.0 / _height_of_display, rotated to match the direction
float angle = atan2f(scanSpeedYfl, scanSpeedXfl);
float halfLineWidth = (float)_height_of_display * 1.9f;
_widths[0][0] = (sinf(angle) / halfLineWidth) * UINT32_MAX;
_widths[0][1] = (cosf(angle) / halfLineWidth) * UINT32_MAX;
_widths[0][0] = (sinf(angle) / halfLineWidth) * kCRTFixedPointRange;
_widths[0][1] = (cosf(angle) / halfLineWidth) * kCRTFixedPointRange;
// generate buffers for signal storage as requested — format is
// number of buffers, size of buffer 1, size of buffer 2...
@ -106,7 +109,7 @@ CRT::SyncEvent CRT::next_vertical_sync_event(bool vsync_is_charging, int cycles_
int proposedSyncTime = cycles_to_run_for;
// have we overrun the maximum permitted number of horizontal syncs for this frame?
if (!_vretrace_counter && _rasterPosition.y == 0xffffffff) {
if (!_vretrace_counter && _rasterPosition.y == kCRTFixedPointRange) {
proposedSyncTime = 0;
proposedEvent = SyncEvent::StartVSync;
}
@ -121,6 +124,7 @@ CRT::SyncEvent CRT::next_vertical_sync_event(bool vsync_is_charging, int cycles_
// will an ongoing vertical sync end?
if (_vretrace_counter > 0) {
// && _rasterPosition.y > ((kCRTFixedPointRange * 3) >> 2))
if (_vretrace_counter < proposedSyncTime) {
proposedSyncTime = _vretrace_counter;
proposedEvent = SyncEvent::EndVSync;
@ -195,10 +199,10 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool
if(next_run)
{
// set the type, initial raster position and type of this run
next_run[0] = next_run[20] = (_rasterPosition.x + width[0]) >> 16;
next_run[1] = next_run[21] = (_rasterPosition.y + width[1]) >> 16;
next_run[4] = (_rasterPosition.x - width[0]) >> 16;
next_run[5] = (_rasterPosition.y - width[1]) >> 16;
next_run[0] = next_run[20] = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
next_run[1] = next_run[21] = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
next_run[4] = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
next_run[5] = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
next_run[2] = next_run[6] = next_run[22] = tex_x;
next_run[3] = next_run[7] = next_run[23] = tex_y;
@ -208,23 +212,21 @@ void CRT::advance_cycles(int number_of_cycles, bool hsync_requested, const bool
if (_is_in_hsync)
_rasterPosition.x = (uint32_t)std::max((int64_t)0, (int64_t)_rasterPosition.x - number_of_cycles * (int64_t)_retraceSpeed.x);
else
_rasterPosition.x = (uint32_t)std::min((int64_t)UINT32_MAX, (int64_t)_rasterPosition.x + number_of_cycles * (int64_t)_scanSpeed.x);
_rasterPosition.x = (uint32_t)std::min((int64_t)kCRTFixedPointRange, (int64_t)_rasterPosition.x + number_of_cycles * (int64_t)_scanSpeed.x);
if (_vretrace_counter > 0)
_rasterPosition.y = (uint32_t)std::max((int64_t)0, (int64_t)_rasterPosition.y - number_of_cycles * (int64_t)_retraceSpeed.y);
else
_rasterPosition.y = (uint32_t)std::min((int64_t)UINT32_MAX, (int64_t)_rasterPosition.y + number_of_cycles * (int64_t)_scanSpeed.y);
_rasterPosition.y = (uint32_t)std::min((int64_t)kCRTFixedPointRange, (int64_t)_rasterPosition.y + number_of_cycles * (int64_t)_scanSpeed.y);
if(next_run)
{
// store the final raster position
next_run[8] = (_rasterPosition.x - width[0]) >> 16;
next_run[9] = (_rasterPosition.y - width[1]) >> 16;
next_run[12] = (_rasterPosition.x - width[0]) >> 16;
next_run[13] = (_rasterPosition.y - width[1]) >> 16;
next_run[8] = next_run[12] = (kCRTFixedPointOffset + _rasterPosition.x - width[0]) >> 16;
next_run[9] = next_run[13] = (kCRTFixedPointOffset + _rasterPosition.y - width[1]) >> 16;
next_run[16] = (_rasterPosition.x + width[0]) >> 16;
next_run[17] = (_rasterPosition.y + width[1]) >> 16;
next_run[16] = (kCRTFixedPointOffset + _rasterPosition.x + width[0]) >> 16;
next_run[17] = (kCRTFixedPointOffset + _rasterPosition.y + width[1]) >> 16;
// if this is a data run then advance the buffer pointer
if(type == Type::Data) tex_x += next_run_length / _time_multiplier;