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680 lines
24 KiB
C++
680 lines
24 KiB
C++
//
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// TIA.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 28/01/2017.
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// Copyright 2017 Thomas Harte. All rights reserved.
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//
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#include "TIA.hpp"
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#include <cassert>
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#include <cstring>
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using namespace Atari2600;
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namespace {
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const int cycles_per_line = 228;
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const int first_pixel_cycle = 68;
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const int sync_flag = 0x1;
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const int blank_flag = 0x2;
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uint8_t reverse_table[256];
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}
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TIA::TIA(bool create_crt) {
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if(create_crt) {
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crt_.reset(new Outputs::CRT::CRT(cycles_per_line * 2 - 1, 1, Outputs::CRT::DisplayType::NTSC60, 1));
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crt_->set_video_signal(Outputs::CRT::VideoSignal::Composite);
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set_output_mode(OutputMode::NTSC);
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}
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for(int c = 0; c < 256; c++) {
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reverse_table[c] = static_cast<uint8_t>(
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((c & 0x01) << 7) | ((c & 0x02) << 5) | ((c & 0x04) << 3) | ((c & 0x08) << 1) |
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((c & 0x10) >> 1) | ((c & 0x20) >> 3) | ((c & 0x40) >> 5) | ((c & 0x80) >> 7)
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);
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}
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for(int c = 0; c < 64; c++) {
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bool has_playfield = c & static_cast<int>(CollisionType::Playfield);
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bool has_ball = c & static_cast<int>(CollisionType::Ball);
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bool has_player0 = c & static_cast<int>(CollisionType::Player0);
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bool has_player1 = c & static_cast<int>(CollisionType::Player1);
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bool has_missile0 = c & static_cast<int>(CollisionType::Missile0);
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bool has_missile1 = c & static_cast<int>(CollisionType::Missile1);
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uint8_t collision_registers[8];
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collision_registers[0] = ((has_missile0 && has_player1) ? 0x80 : 0x00) | ((has_missile0 && has_player0) ? 0x40 : 0x00);
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collision_registers[1] = ((has_missile1 && has_player0) ? 0x80 : 0x00) | ((has_missile1 && has_player1) ? 0x40 : 0x00);
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collision_registers[2] = ((has_playfield && has_player0) ? 0x80 : 0x00) | ((has_ball && has_player0) ? 0x40 : 0x00);
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collision_registers[3] = ((has_playfield && has_player1) ? 0x80 : 0x00) | ((has_ball && has_player1) ? 0x40 : 0x00);
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collision_registers[4] = ((has_playfield && has_missile0) ? 0x80 : 0x00) | ((has_ball && has_missile0) ? 0x40 : 0x00);
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collision_registers[5] = ((has_playfield && has_missile1) ? 0x80 : 0x00) | ((has_ball && has_missile1) ? 0x40 : 0x00);
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collision_registers[6] = ((has_playfield && has_ball) ? 0x80 : 0x00);
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collision_registers[7] = ((has_player0 && has_player1) ? 0x80 : 0x00) | ((has_missile0 && has_missile1) ? 0x40 : 0x00);
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collision_flags_by_buffer_vaules_[c] =
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(collision_registers[0] >> 6) |
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(collision_registers[1] >> 4) |
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(collision_registers[2] >> 2) |
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(collision_registers[3] >> 0) |
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(collision_registers[4] << 2) |
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(collision_registers[5] << 4) |
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(collision_registers[6] << 6) |
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(collision_registers[7] << 8);
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// all priority modes show the background if nothing else is present
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::Standard)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreLeft)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreRight)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::OnTop)][c] = static_cast<uint8_t>(ColourIndex::Background);
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// test 1 for standard priority: if there is a playfield or ball pixel, plot that colour
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if(has_playfield || has_ball) {
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::Standard)][c] = static_cast<uint8_t>(ColourIndex::PlayfieldBall);
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}
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// test 1 for score mode: if there is a ball pixel, plot that colour
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if(has_ball) {
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreLeft)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreRight)][c] = static_cast<uint8_t>(ColourIndex::PlayfieldBall);
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}
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// test 1 for on-top mode, test 2 for everbody else: if there is a player 1 or missile 1 pixel, plot that colour
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if(has_player1 || has_missile1) {
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::Standard)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreLeft)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreRight)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::OnTop)][c] = static_cast<uint8_t>(ColourIndex::PlayerMissile1);
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}
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// in the right-hand side of score mode, the playfield has the same priority as player 1
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if(has_playfield) {
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreRight)][c] = static_cast<uint8_t>(ColourIndex::PlayerMissile1);
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}
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// next test for everybody: if there is a player 0 or missile 0 pixel, plot that colour instead
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if(has_player0 || has_missile0) {
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::Standard)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreLeft)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreRight)][c] =
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::OnTop)][c] = static_cast<uint8_t>(ColourIndex::PlayerMissile0);
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}
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// if this is the left-hand side of score mode, the playfield has the same priority as player 0
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if(has_playfield) {
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreLeft)][c] = static_cast<uint8_t>(ColourIndex::PlayerMissile0);
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}
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// a final test for 'on top' priority mode: if the playfield or ball are visible, prefer that colour to all others
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if(has_playfield || has_ball) {
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colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::OnTop)][c] = static_cast<uint8_t>(ColourIndex::PlayfieldBall);
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}
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}
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}
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TIA::TIA() : TIA(true) {}
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TIA::TIA(std::function<void(uint8_t *output_buffer)> line_end_function) : TIA(false) {
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line_end_function_ = line_end_function;
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}
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void TIA::set_output_mode(Atari2600::TIA::OutputMode output_mode) {
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Outputs::CRT::DisplayType display_type;
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if(output_mode == OutputMode::NTSC) {
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crt_->set_svideo_sampling_function(
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"vec2 svideo_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase)"
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"{"
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"uint c = texture(texID, coordinate).r;"
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"uint y = c & 14u;"
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"uint iPhase = (c >> 4);"
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"float phaseOffset = 6.283185308 * float(iPhase) / 13.0 + 5.074880441076923;"
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"return vec2(float(y) / 14.0, step(1, iPhase) * cos(phase + phaseOffset));"
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"}");
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display_type = Outputs::CRT::DisplayType::NTSC60;
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} else {
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crt_->set_svideo_sampling_function(
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"vec2 svideo_sample(usampler2D texID, vec2 coordinate, vec2 iCoordinate, float phase)"
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"{"
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"uint c = texture(texID, coordinate).r;"
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"uint y = c & 14u;"
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"uint iPhase = (c >> 4);"
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"uint direction = iPhase & 1u;"
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"float phaseOffset = float(7u - direction) + (float(direction) - 0.5) * 2.0 * float(iPhase >> 1);"
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"phaseOffset *= 6.283185308 / 12.0;"
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"return vec2(float(y) / 14.0, step(4, (iPhase + 2u) & 15u) * cos(phase + phaseOffset));"
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"}");
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display_type = Outputs::CRT::DisplayType::PAL50;
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}
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crt_->set_video_signal(Outputs::CRT::VideoSignal::Composite);
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// line number of cycles in a line of video is one less than twice the number of clock cycles per line; the Atari
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// outputs 228 colour cycles of material per line when an NTSC line 227.5. Since all clock numbers will be doubled
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// later, cycles_per_line * 2 - 1 is therefore the real length of an NTSC line, even though we're going to supply
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// cycles_per_line * 2 cycles of information from one sync edge to the next
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crt_->set_new_display_type(cycles_per_line * 2 - 1, display_type);
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/* speaker_->set_input_rate(static_cast<float>(get_clock_rate() / 38.0));*/
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}
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void TIA::run_for(const Cycles cycles) {
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int number_of_cycles = cycles.as_int();
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// if part way through a line, definitely perform a partial, at most up to the end of the line
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if(horizontal_counter_) {
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int output_cycles = std::min(number_of_cycles, cycles_per_line - horizontal_counter_);
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output_for_cycles(output_cycles);
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number_of_cycles -= output_cycles;
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}
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// output full lines for as long as possible
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while(number_of_cycles >= cycles_per_line) {
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output_line();
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number_of_cycles -= cycles_per_line;
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}
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// partly start a new line if necessary
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if(number_of_cycles) {
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output_for_cycles(number_of_cycles);
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}
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}
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void TIA::set_sync(bool sync) {
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output_mode_ = (output_mode_ & ~sync_flag) | (sync ? sync_flag : 0);
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}
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void TIA::set_blank(bool blank) {
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output_mode_ = (output_mode_ & ~blank_flag) | (blank ? blank_flag : 0);
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}
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void TIA::reset_horizontal_counter() {
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}
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int TIA::get_cycles_until_horizontal_blank(const Cycles from_offset) {
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return (cycles_per_line - (horizontal_counter_ + from_offset.as_int()) % cycles_per_line) % cycles_per_line;
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}
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void TIA::set_background_colour(uint8_t colour) {
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colour_palette_[static_cast<int>(ColourIndex::Background)] = colour;
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}
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void TIA::set_playfield(uint16_t offset, uint8_t value) {
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assert(offset >= 0 && offset < 3);
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switch(offset) {
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case 0:
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background_[1] = (background_[1] & 0x0ffff) | (static_cast<uint32_t>(reverse_table[value & 0xf0]) << 16);
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background_[0] = (background_[0] & 0xffff0) | static_cast<uint32_t>(value >> 4);
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break;
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case 1:
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background_[1] = (background_[1] & 0xf00ff) | (static_cast<uint32_t>(value) << 8);
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background_[0] = (background_[0] & 0xff00f) | (static_cast<uint32_t>(reverse_table[value]) << 4);
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break;
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case 2:
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background_[1] = (background_[1] & 0xfff00) | reverse_table[value];
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background_[0] = (background_[0] & 0x00fff) | (static_cast<uint32_t>(value) << 12);
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break;
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}
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}
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void TIA::set_playfield_control_and_ball_size(uint8_t value) {
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background_half_mask_ = value & 1;
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switch(value & 6) {
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case 0:
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playfield_priority_ = PlayfieldPriority::Standard;
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break;
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case 2:
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playfield_priority_ = PlayfieldPriority::Score;
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break;
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case 4:
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case 6:
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playfield_priority_ = PlayfieldPriority::OnTop;
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break;
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}
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ball_.size = 1 << ((value >> 4)&3);
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}
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void TIA::set_playfield_ball_colour(uint8_t colour) {
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colour_palette_[static_cast<int>(ColourIndex::PlayfieldBall)] = colour;
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}
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void TIA::set_player_number_and_size(int player, uint8_t value) {
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assert(player >= 0 && player < 2);
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int size = 0;
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switch(value & 7) {
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case 0: case 1: case 2: case 3: case 4:
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player_[player].copy_flags = value & 7;
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break;
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case 5:
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size = 1;
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player_[player].copy_flags = 0;
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break;
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case 6:
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player_[player].copy_flags = 6;
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break;
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case 7:
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size = 2;
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player_[player].copy_flags = 0;
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break;
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}
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missile_[player].size = 1 << ((value >> 4)&3);
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missile_[player].copy_flags = player_[player].copy_flags;
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player_[player].adder = 4 >> size;
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}
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void TIA::set_player_graphic(int player, uint8_t value) {
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assert(player >= 0 && player < 2);
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player_[player].graphic[1] = value;
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player_[player^1].graphic[0] = player_[player^1].graphic[1];
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if(player) ball_.enabled[0] = ball_.enabled[1];
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}
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void TIA::set_player_reflected(int player, bool reflected) {
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assert(player >= 0 && player < 2);
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player_[player].reverse_mask = reflected ? 7 : 0;
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}
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void TIA::set_player_delay(int player, bool delay) {
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assert(player >= 0 && player < 2);
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player_[player].graphic_index = delay ? 0 : 1;
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}
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void TIA::set_player_position(int player) {
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assert(player >= 0 && player < 2);
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// players have an extra clock of delay before output and don't display upon reset;
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// both aims are achieved by setting to -1 because: (i) it causes the clock to be
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// one behind its real hardware value, creating the extra delay; and (ii) the player
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// code is written to start a draw upon wraparound from 159 to 0, so -1 is the
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// correct option rather than 159.
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player_[player].position = -1;
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}
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void TIA::set_player_motion(int player, uint8_t motion) {
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assert(player >= 0 && player < 2);
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player_[player].motion = (motion >> 4)&0xf;
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}
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void TIA::set_player_missile_colour(int player, uint8_t colour) {
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assert(player >= 0 && player < 2);
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colour_palette_[static_cast<int>(ColourIndex::PlayerMissile0) + player] = colour;
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}
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void TIA::set_missile_enable(int missile, bool enabled) {
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assert(missile >= 0 && missile < 2);
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missile_[missile].enabled = enabled;
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}
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void TIA::set_missile_position(int missile) {
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assert(missile >= 0 && missile < 2);
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missile_[missile].position = 0;
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}
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void TIA::set_missile_position_to_player(int missile, bool lock) {
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assert(missile >= 0 && missile < 2);
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missile_[missile].locked_to_player = lock;
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player_[missile].latched_pixel4_time = -1;
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}
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void TIA::set_missile_motion(int missile, uint8_t motion) {
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assert(missile >= 0 && missile < 2);
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missile_[missile].motion = (motion >> 4)&0xf;
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}
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void TIA::set_ball_enable(bool enabled) {
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ball_.enabled[1] = enabled;
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}
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void TIA::set_ball_delay(bool delay) {
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ball_.enabled_index = delay ? 0 : 1;
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}
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void TIA::set_ball_position() {
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ball_.position = 0;
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// setting the ball position also triggers a draw
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ball_.reset_pixels(0);
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}
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void TIA::set_ball_motion(uint8_t motion) {
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ball_.motion = (motion >> 4) & 0xf;
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}
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void TIA::move() {
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horizontal_blank_extend_ = true;
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player_[0].is_moving = player_[1].is_moving = missile_[0].is_moving = missile_[1].is_moving = ball_.is_moving = true;
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player_[0].motion_step = player_[1].motion_step = missile_[0].motion_step = missile_[1].motion_step = ball_.motion_step = 15;
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player_[0].motion_time = player_[1].motion_time = missile_[0].motion_time = missile_[1].motion_time = ball_.motion_time = (horizontal_counter_ + 3) & ~3;
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}
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void TIA::clear_motion() {
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player_[0].motion = player_[1].motion = missile_[0].motion = missile_[1].motion = ball_.motion = 0;
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}
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uint8_t TIA::get_collision_flags(int offset) {
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return static_cast<uint8_t>((collision_flags_ >> (offset << 1)) << 6) & 0xc0;
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}
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void TIA::clear_collision_flags() {
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collision_flags_ = 0;
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}
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void TIA::output_for_cycles(int number_of_cycles) {
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/*
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Line timing is oriented around 0 being the start of the right-hand side vertical blank;
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a wsync synchronises the CPU to horizontal_counter_ = 0. All timing below is in terms of the
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NTSC colour clock.
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Therefore, each line is composed of:
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16 cycles: blank ; -> 16
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16 cycles: sync ; -> 32
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16 cycles: colour burst ; -> 48
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20 cycles: blank ; -> 68
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8 cycles: blank or pixels, depending on whether the blank extend bit is set
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152 cycles: pixels
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*/
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int output_cursor = horizontal_counter_;
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horizontal_counter_ += number_of_cycles;
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bool is_reset = output_cursor < 224 && horizontal_counter_ >= 224;
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if(!output_cursor) {
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if(line_end_function_) line_end_function_(collision_buffer_);
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std::memset(collision_buffer_, 0, sizeof(collision_buffer_));
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ball_.motion_time %= 228;
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player_[0].motion_time %= 228;
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player_[1].motion_time %= 228;
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missile_[0].motion_time %= 228;
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missile_[1].motion_time %= 228;
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}
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// accumulate an OR'd version of the output into the collision buffer
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int latent_start = output_cursor + 4;
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int latent_end = horizontal_counter_ + 4;
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draw_playfield(latent_start, latent_end);
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draw_object<Player>(player_[0], static_cast<uint8_t>(CollisionType::Player0), output_cursor, horizontal_counter_);
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draw_object<Player>(player_[1], static_cast<uint8_t>(CollisionType::Player1), output_cursor, horizontal_counter_);
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draw_missile(missile_[0], player_[0], static_cast<uint8_t>(CollisionType::Missile0), output_cursor, horizontal_counter_);
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draw_missile(missile_[1], player_[1], static_cast<uint8_t>(CollisionType::Missile1), output_cursor, horizontal_counter_);
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draw_object<Ball>(ball_, static_cast<uint8_t>(CollisionType::Ball), output_cursor, horizontal_counter_);
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// convert to television signals
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#define Period(function, target) \
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if(output_cursor < target) { \
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if(horizontal_counter_ <= target) { \
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if(crt_) crt_->function(static_cast<unsigned int>((horizontal_counter_ - output_cursor) * 2)); \
|
|
horizontal_counter_ %= cycles_per_line; \
|
|
return; \
|
|
} else { \
|
|
if(crt_) crt_->function(static_cast<unsigned int>((target - output_cursor) * 2)); \
|
|
output_cursor = target; \
|
|
} \
|
|
}
|
|
|
|
switch(output_mode_) {
|
|
default:
|
|
Period(output_blank, 16)
|
|
Period(output_sync, 32)
|
|
Period(output_default_colour_burst, 48)
|
|
Period(output_blank, 68)
|
|
break;
|
|
case sync_flag:
|
|
case sync_flag | blank_flag:
|
|
Period(output_sync, 16)
|
|
Period(output_blank, 32)
|
|
Period(output_default_colour_burst, 48)
|
|
Period(output_sync, 228)
|
|
break;
|
|
}
|
|
|
|
#undef Period
|
|
|
|
if(output_mode_ & blank_flag) {
|
|
if(pixel_target_) {
|
|
output_pixels(pixels_start_location_, output_cursor);
|
|
if(crt_) {
|
|
const unsigned int data_length = static_cast<unsigned int>(output_cursor - pixels_start_location_);
|
|
crt_->output_data(data_length * 2, data_length);
|
|
}
|
|
pixel_target_ = nullptr;
|
|
pixels_start_location_ = 0;
|
|
}
|
|
int duration = std::min(228, horizontal_counter_) - output_cursor;
|
|
if(crt_) crt_->output_blank(static_cast<unsigned int>(duration * 2));
|
|
} else {
|
|
if(!pixels_start_location_ && crt_) {
|
|
pixels_start_location_ = output_cursor;
|
|
pixel_target_ = crt_->allocate_write_area(160);
|
|
}
|
|
|
|
// convert that into pixels
|
|
if(pixel_target_) output_pixels(output_cursor, horizontal_counter_);
|
|
|
|
// accumulate collision flags
|
|
while(output_cursor < horizontal_counter_) {
|
|
collision_flags_ |= collision_flags_by_buffer_vaules_[collision_buffer_[output_cursor - first_pixel_cycle]];
|
|
output_cursor++;
|
|
}
|
|
|
|
if(horizontal_counter_ == cycles_per_line && crt_) {
|
|
const unsigned int data_length = static_cast<unsigned int>(output_cursor - pixels_start_location_);
|
|
crt_->output_data(data_length * 2, data_length);
|
|
pixel_target_ = nullptr;
|
|
pixels_start_location_ = 0;
|
|
}
|
|
}
|
|
|
|
if(is_reset) horizontal_blank_extend_ = false;
|
|
|
|
horizontal_counter_ %= cycles_per_line;
|
|
}
|
|
|
|
void TIA::output_pixels(int start, int end) {
|
|
start = std::max(start, pixels_start_location_);
|
|
int target_position = start - pixels_start_location_;
|
|
|
|
if(start < first_pixel_cycle+8 && horizontal_blank_extend_) {
|
|
while(start < end && start < first_pixel_cycle+8) {
|
|
pixel_target_[target_position] = 0;
|
|
start++;
|
|
target_position++;
|
|
}
|
|
}
|
|
|
|
if(playfield_priority_ == PlayfieldPriority::Score) {
|
|
while(start < end && start < first_pixel_cycle + 80) {
|
|
uint8_t buffer_value = collision_buffer_[start - first_pixel_cycle];
|
|
pixel_target_[target_position] = colour_palette_[colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreLeft)][buffer_value]];
|
|
start++;
|
|
target_position++;
|
|
}
|
|
while(start < end) {
|
|
uint8_t buffer_value = collision_buffer_[start - first_pixel_cycle];
|
|
pixel_target_[target_position] = colour_palette_[colour_mask_by_mode_collision_flags_[static_cast<int>(ColourMode::ScoreRight)][buffer_value]];
|
|
start++;
|
|
target_position++;
|
|
}
|
|
} else {
|
|
int table_index = static_cast<int>((playfield_priority_ == PlayfieldPriority::Standard) ? ColourMode::Standard : ColourMode::OnTop);
|
|
while(start < end) {
|
|
uint8_t buffer_value = collision_buffer_[start - first_pixel_cycle];
|
|
pixel_target_[target_position] = colour_palette_[colour_mask_by_mode_collision_flags_[table_index][buffer_value]];
|
|
start++;
|
|
target_position++;
|
|
}
|
|
}
|
|
}
|
|
|
|
void TIA::output_line() {
|
|
switch(output_mode_) {
|
|
default:
|
|
// TODO: optimise special case
|
|
output_for_cycles(cycles_per_line);
|
|
break;
|
|
case sync_flag:
|
|
case sync_flag | blank_flag:
|
|
if(crt_) {
|
|
crt_->output_sync(32);
|
|
crt_->output_blank(32);
|
|
crt_->output_sync(392);
|
|
}
|
|
horizontal_blank_extend_ = false;
|
|
break;
|
|
case blank_flag:
|
|
if(crt_) {
|
|
crt_->output_blank(32);
|
|
crt_->output_sync(32);
|
|
crt_->output_default_colour_burst(32);
|
|
crt_->output_blank(360);
|
|
}
|
|
horizontal_blank_extend_ = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// MARK: - Playfield output
|
|
|
|
void TIA::draw_playfield(int start, int end) {
|
|
// don't do anything if this window ends too early
|
|
if(end < first_pixel_cycle) return;
|
|
|
|
// clip to drawable bounds
|
|
start = std::max(start, first_pixel_cycle);
|
|
end = std::min(end, 228);
|
|
|
|
// proceed along four-pixel boundaries, plotting four pixels at a time
|
|
int aligned_position = (start + 3)&~3;
|
|
while(aligned_position < end) {
|
|
int offset = (aligned_position - first_pixel_cycle) >> 2;
|
|
uint32_t value = ((background_[(offset/20)&background_half_mask_] >> (offset%20))&1) * 0x01010101;
|
|
*reinterpret_cast<uint32_t *>(&collision_buffer_[aligned_position - first_pixel_cycle]) |= value;
|
|
aligned_position += 4;
|
|
}
|
|
}
|
|
|
|
// MARK: - Motion
|
|
|
|
template<class T> void TIA::perform_motion_step(T &object) {
|
|
if((object.motion_step ^ (object.motion ^ 8)) == 0xf) {
|
|
object.is_moving = false;
|
|
} else {
|
|
if(object.position == 159) object.reset_pixels(0);
|
|
else if(object.position == 15 && object.copy_flags&1) object.reset_pixels(1);
|
|
else if(object.position == 31 && object.copy_flags&2) object.reset_pixels(2);
|
|
else if(object.position == 63 && object.copy_flags&4) object.reset_pixels(3);
|
|
else object.skip_pixels(1, object.motion_time);
|
|
object.position = (object.position + 1) % 160;
|
|
object.motion_step --;
|
|
object.motion_time += 4;
|
|
}
|
|
}
|
|
|
|
template<class T> void TIA::perform_border_motion(T &object, int start, int end) {
|
|
while(object.is_moving && object.motion_time < end)
|
|
perform_motion_step<T>(object);
|
|
}
|
|
|
|
template<class T> void TIA::draw_object(T &object, const uint8_t collision_identity, int start, int end) {
|
|
int first_pixel = first_pixel_cycle - 4 + (horizontal_blank_extend_ ? 8 : 0);
|
|
|
|
object.dequeue_pixels(collision_buffer_, collision_identity, end - first_pixel_cycle);
|
|
|
|
// movement works across the entire screen, so do work that falls outside of the pixel area
|
|
if(start < first_pixel) {
|
|
perform_border_motion<T>(object, start, std::min(end, first_pixel));
|
|
}
|
|
|
|
// don't continue to do any drawing if this window ends too early
|
|
if(end < first_pixel) return;
|
|
if(start < first_pixel) start = first_pixel;
|
|
if(start >= end) return;
|
|
|
|
// perform the visible part of the line, if any
|
|
if(start < 224) {
|
|
draw_object_visible<T>(object, collision_identity, start - first_pixel_cycle + 4, std::min(end - first_pixel_cycle + 4, 160), end - first_pixel_cycle);
|
|
}
|
|
|
|
// move further if required
|
|
if(object.is_moving && end >= 224 && object.motion_time < end) {
|
|
perform_motion_step<T>(object);
|
|
}
|
|
}
|
|
|
|
template<class T> void TIA::draw_object_visible(T &object, const uint8_t collision_identity, int start, int end, int time_now) {
|
|
// perform a miniature event loop on (i) triggering draws; (ii) drawing; and (iii) motion
|
|
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(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;
|
|
int next_copy_id = 0;
|
|
if(object.copy_flags) {
|
|
if(object.position < 16 && object.copy_flags&1) {
|
|
next_copy = 16;
|
|
next_copy_id = 1;
|
|
} else if(object.position < 32 && object.copy_flags&2) {
|
|
next_copy = 32;
|
|
next_copy_id = 2;
|
|
} else if(object.position < 64 && object.copy_flags&4) {
|
|
next_copy = 64;
|
|
next_copy_id = 3;
|
|
}
|
|
}
|
|
|
|
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
|
|
const int length = next_event_time - start;
|
|
|
|
// enqueue a future intention to draw pixels if spitting them out now would violate accuracy;
|
|
// otherwise draw them now
|
|
if(object.enqueues && next_event_time > time_now) {
|
|
if(start < time_now) {
|
|
object.output_pixels(&collision_buffer_[start], time_now - start, collision_identity, start + first_pixel_cycle - 4);
|
|
object.enqueue_pixels(time_now, next_event_time, time_now + first_pixel_cycle - 4);
|
|
} else {
|
|
object.enqueue_pixels(start, next_event_time, start + first_pixel_cycle - 4);
|
|
}
|
|
} else {
|
|
object.output_pixels(&collision_buffer_[start], length, collision_identity, start + first_pixel_cycle - 4);
|
|
}
|
|
|
|
// the next interesting event is after next_event_time cycles, so progress
|
|
object.position = (object.position + length) % 160;
|
|
start = next_event_time;
|
|
|
|
// if the event is a motion tick, apply; if it's a draw trigger, trigger a draw
|
|
if(object.is_moving && start == next_motion_time) {
|
|
perform_motion_step(object);
|
|
next_motion_time += 4;
|
|
} else if(start == next_copy_time) {
|
|
object.reset_pixels(next_copy_id);
|
|
}
|
|
}
|
|
}
|
|
|
|
// MARK: - Missile drawing
|
|
|
|
void TIA::draw_missile(Missile &missile, Player &player, const uint8_t collision_identity, int start, int end) {
|
|
if(!missile.locked_to_player || player.latched_pixel4_time < 0) {
|
|
draw_object<Missile>(missile, collision_identity, start, end);
|
|
} else {
|
|
draw_object<Missile>(missile, collision_identity, start, player.latched_pixel4_time);
|
|
missile.position = 0;
|
|
draw_object<Missile>(missile, collision_identity, player.latched_pixel4_time, end);
|
|
player.latched_pixel4_time = -1;
|
|
}
|
|
}
|