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Made an effort to implement proper pixel output for sprites.

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This commit is contained in:
Thomas Harte 2017-02-12 14:01:50 -05:00
parent 40954d6a2a
commit 9ce68c38ae
2 changed files with 37 additions and 10 deletions
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44
Machines/Atari2600/TIA.cpp
View File

@ -631,7 +631,7 @@ void TIA::draw_player(Player &player, CollisionType collision_identity, const in
next_event_time = movement_time + 4;
}
// is the next event a graphics draw?
// is the next event a graphics trigger?
int next_copy = 160;
if(player.graphic)
{
@ -650,8 +650,31 @@ void TIA::draw_player(Player &player, CollisionType collision_identity, const in
if(next_copy_time < next_event_time) next_event_time = next_copy_time;
}
// maybe a deferred draw?
if(player.output_delay > 0)
{
if(start + player.output_delay < next_event_time) next_event_time = start + player.output_delay;
}
// the decision is to progress by length
const int length = next_event_time - start;
if(player.pixel_position < 32)
{
int adder = 4 >> player.size;
// player.pixel_position &= ~(adder - 1);
int output_cursor = 0;
while(player.pixel_position < 32 && output_cursor < length)
{
int shift = (player.pixel_position >> 2) ^ player.reverse_mask;
collision_buffer_[start + output_cursor - first_pixel_cycle] |= ((player.graphic >> shift)&1) * (uint8_t)collision_identity;
output_cursor++;
player.pixel_position += adder;
}
}
// the next interesting event is after next_event_time cycles, so progress
position = (position + next_event_time - start) % 160;
position = (position + length) % 160;
start = next_event_time;
// if the event is a motion tick, apply
@ -661,16 +684,17 @@ void TIA::draw_player(Player &player, CollisionType collision_identity, const in
movement_time += 4;
}
// if it's a draw trigger, draw (TODO: use the actual graphic)
// if an output delay is being counted down, continue doing so
if(player.output_delay > 0)
{
player.output_delay -= length;
if(!player.output_delay) player.pixel_position = 0;
}
// if it's a draw trigger, trigger a draw
if(position == (next_copy % 160))
{
int cursor = start + 5 - first_pixel_cycle;
int terminus = std::min(160, cursor+8);
while(cursor < terminus)
{
collision_buffer_[cursor] |= (uint8_t)collision_identity;
cursor++;
}
player.output_delay = 5;
}
}
}

3
Machines/Atari2600/TIA.hpp
View File

@ -134,6 +134,9 @@ class TIA {
int copy_flags; // a bit field, corresponding to the first few values of NUSIZ
uint8_t graphic; // the player graphic
int reverse_mask; // 7 for a reflected player, 0 for normal
int pixel_position;
int output_delay;
} player_[2];
// missile state