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Reorganised state, with an eye towards unifying object motion and triggers.

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This commit is contained in:
Thomas Harte 2017-02-20 17:58:28 -05:00
parent 87afa9140e
commit 57f434c199
2 changed files with 58 additions and 43 deletions
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75
Machines/Atari2600/TIA.cpp
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@ -26,9 +26,6 @@ TIA::TIA(bool create_crt) :
pixel_target_(nullptr),
background_{0, 0},
background_half_mask_(0),
position_{0, 0, 0, 0, 0},
motion_{0, 0, 0, 0, 0},
is_moving_{false, false, false, false, false},
horizontal_blank_extend_(false),
collision_flags_(0)
{
@ -330,12 +327,12 @@ void TIA::set_player_position(int player)
// one behind its real hardware value, creating the extra delay; and (ii) the player
// code is written to start a draw upon wraparound from 159 to 0, so -1 is the
// correct option rather than 159.
position_[(int)MotionIndex::Player0 + player] = -1;
object_[(int)MotionIndex::Player0 + player].position = -1;
}
void TIA::set_player_motion(int player, uint8_t motion)
{
motion_[(int)MotionIndex::Player0 + player] = (motion >> 4)&0xf;
object_[(int)MotionIndex::Player0 + player].motion = (motion >> 4)&0xf;
}
void TIA::set_player_missile_colour(int player, uint8_t colour)
@ -371,7 +368,7 @@ void TIA::set_ball_delay(bool delay)
void TIA::set_ball_position()
{
position_[(int)MotionIndex::Ball] = 0;
object_[(int)MotionIndex::Ball].position = 0;
// setting the ball position also triggers a draw
ball_.pixel_position = ball_.size;
@ -379,20 +376,20 @@ void TIA::set_ball_position()
void TIA::set_ball_motion(uint8_t motion)
{
motion_[(int)MotionIndex::Ball] = (motion >> 4) & 0xf;
object_[(int)MotionIndex::Ball].motion = (motion >> 4) & 0xf;
}
void TIA::move()
{
horizontal_blank_extend_ = true;
is_moving_[0] = is_moving_[1] = is_moving_[2] = is_moving_[3] = is_moving_[4] = true;
motion_step_[0] = motion_step_[1] = motion_step_[2] = motion_step_[3] = motion_step_[4] = 15;
motion_time_[0] = motion_time_[1] = motion_time_[2] = motion_time_[3] = motion_time_[4] = (horizontal_counter_ + 3) & ~3;
object_[0].is_moving = object_[1].is_moving = object_[2].is_moving = object_[3].is_moving = object_[4].is_moving = true;
object_[0].motion_step = object_[1].motion_step = object_[2].motion_step = object_[3].motion_step = object_[4].motion_step = 15;
object_[0].motion_time = object_[1].motion_time = object_[2].motion_time = object_[3].motion_time = object_[4].motion_time = (horizontal_counter_ + 3) & ~3;
}
void TIA::clear_motion()
{
motion_[0] = motion_[1] = motion_[2] = motion_[3] = motion_[4] = 0;
object_[0].motion = object_[1].motion = object_[2].motion = object_[3].motion = object_[4].motion = 0;
}
uint8_t TIA::get_collision_flags(int offset)
@ -429,7 +426,7 @@ void TIA::output_for_cycles(int number_of_cycles)
if(line_end_function_) line_end_function_(collision_buffer_.data());
memset(collision_buffer_.data(), 0, 160); // sizeof(collision_buffer_)
horizontal_blank_extend_ = false;
for(int c = 0; c < 5; c++) motion_time_[c] %= 228;
for(int c = 0; c < 5; c++) object_[c].motion_time %= 228;
}
// accumulate an OR'd version of the output into the collision buffer
@ -621,27 +618,29 @@ void TIA::draw_playfield(int start, int end)
void TIA::perform_motion_step(int identity)
{
if((motion_step_[identity] ^ (motion_[identity] ^ 8)) == 0xf)
is_moving_[identity] = false;
Object &object = object_[identity];
if((object.motion_step ^ (object.motion ^ 8)) == 0xf)
object.is_moving = false;
else
{
position_[identity] ++;
motion_step_[identity] --;
motion_time_[identity] += 4;
object.position ++;
object.motion_step --;
object.motion_time += 4;
}
}
int TIA::perform_border_motion(int identity, int start, int end)
{
if(!is_moving_[identity]) return 0;
Object &object = object_[identity];
if(!object.is_moving) return 0;
int steps_taken = 0;
while(is_moving_[identity] && motion_time_[identity] < end)
while(object.is_moving && object.motion_time < end)
{
perform_motion_step(identity);
steps_taken++;
}
position_[identity] %= 160;
object.position %= 160;
return steps_taken;
}
@ -650,35 +649,35 @@ int TIA::perform_border_motion(int identity, int start, int end)
void TIA::draw_player_visible(Player &player, CollisionType collision_identity, const int position_identity, int start, int end)
{
int &position = position_[position_identity];
Object &object = object_[position_identity];
int adder = 4 >> player.size;
// perform a miniature event loop on (i) triggering draws; (ii) drawing; and (iii) motion
int next_motion_time = motion_time_[position_identity] - first_pixel_cycle + 4;
int next_motion_time = object.motion_time - first_pixel_cycle + 4;
while(start < end)
{
int next_event_time = end;
// is the next event a movement tick?
if(is_moving_[position_identity] && next_motion_time < next_event_time)
if(object.is_moving && next_motion_time < next_event_time)
{
next_event_time = next_motion_time;
}
// is the next event a graphics trigger?
int next_copy = 160;
if(position < 16 && player.copy_flags&1)
if(object.position < 16 && player.copy_flags&1)
{
next_copy = 16;
} else if(position < 32 && player.copy_flags&2)
} else if(object.position < 32 && player.copy_flags&2)
{
next_copy = 32;
} else if(position < 64 && player.copy_flags&4)
} else if(object.position < 64 && player.copy_flags&4)
{
next_copy = 64;
}
int next_copy_time = start + next_copy - position;
int next_copy_time = start + next_copy - object.position;
if(next_copy_time < next_event_time) next_event_time = next_copy_time;
// the decision is to progress by length
@ -705,11 +704,11 @@ void TIA::draw_player_visible(Player &player, CollisionType collision_identity,
}
// the next interesting event is after next_event_time cycles, so progress
position = (position + length) % 160;
object.position = (object.position + length) % 160;
start = next_event_time;
// if the event is a motion tick, apply
if(is_moving_[position_identity] && start == next_motion_time)
if(object.is_moving && start == next_motion_time)
{
perform_motion_step(position_identity);
next_motion_time += 4;
@ -746,7 +745,7 @@ void TIA::draw_player(Player &player, CollisionType collision_identity, const in
}
// move further if required
if(is_moving_[position_identity] && end >= 224 && motion_time_[position_identity] < end)
if(object_[position_identity].is_moving && end >= 224 && object_[position_identity].motion_time < end)
{
perform_motion_step(position_identity);
player.pixel_position = std::min(32, player.pixel_position + adder);
@ -787,7 +786,7 @@ void TIA::draw_ball(int start, int end)
}
// move further if required
if(is_moving_[(int)MotionIndex::Ball] && end >= 224 && motion_time_[(int)MotionIndex::Ball] < end)
if(object_[(int)MotionIndex::Ball].is_moving && end >= 224 && object_[(int)MotionIndex::Ball].motion_time < end)
{
perform_motion_step((int)MotionIndex::Ball);
ball_.pixel_position = std::max(0, ball_.pixel_position - 1);
@ -796,16 +795,16 @@ void TIA::draw_ball(int start, int end)
void TIA::draw_ball_visible(int start, int end)
{
int &position = position_[(int)MotionIndex::Ball];
Object &object = object_[(int)MotionIndex::Ball];
// perform a miniature event loop on (i) triggering draws; (ii) drawing; and (iii) motion
int next_motion_time = motion_time_[(int)MotionIndex::Ball] - first_pixel_cycle + 4;
int next_motion_time = object.motion_time - first_pixel_cycle + 4;
while(start < end)
{
int next_event_time = end;
// is the next event a movement tick?
if(is_moving_[(int)MotionIndex::Ball] && next_motion_time < next_event_time)
if(object.is_moving && next_motion_time < next_event_time)
{
next_event_time = next_motion_time;
}
@ -813,7 +812,7 @@ void TIA::draw_ball_visible(int start, int end)
// is the next event a graphics trigger?
if(ball_.enabled[ball_.enabled_index])
{
int time_until_copy = 160 - position;
int time_until_copy = 160 - object.position;
int next_copy_time = start + time_until_copy;
if(next_copy_time < next_event_time) next_event_time = next_copy_time;
}
@ -840,18 +839,18 @@ void TIA::draw_ball_visible(int start, int end)
}
// the next interesting event is after next_event_time cycles, so progress
position = (position + length) % 160;
object.position = (object.position + length) % 160;
start = next_event_time;
// if the event is a motion tick, apply
if(is_moving_[(int)MotionIndex::Ball] && start == next_motion_time)
if(object.is_moving && start == next_motion_time)
{
perform_motion_step((int)MotionIndex::Ball);
next_motion_time += 4;
}
// if it's a draw trigger, trigger a draw
if(!position)
if(!object.position)
{
ball_.pixel_position = ball_.size;
}

26
Machines/Atari2600/TIA.hpp
View File

@ -166,11 +166,27 @@ class TIA {
// movement
bool horizontal_blank_extend_;
int motion_[5];
int motion_step_[5];
int motion_time_[5];
int position_[5];
bool is_moving_[5];
struct Object {
// the two programmer-set values
int position;
int motion;
// motion_step_ is the current motion counter value; motion_time_ is the next time it will fire
int motion_step;
int motion_time;
// indicates whether this object is currently undergoing motion
bool is_moving;
// receives a list of drawing events; 20 is a deliberately over-specified quantity
struct DrawingEvent {
int time;
int copy;
} drawing_events[20];
int draw_event_read_pointer, draw_event_write_pointer;
Object() : draw_event_read_pointer(0), draw_event_write_pointer(0), is_moving(false) {};
} object_[5];
enum class MotionIndex : uint8_t {
Ball,
Player0,