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294 lines
9.4 KiB
C++
294 lines
9.4 KiB
C++
//
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// Draw.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 05/01/2023.
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// Copyright © 2023 Thomas Harte. All rights reserved.
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//
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#ifndef Draw_hpp
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#define Draw_hpp
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// MARK: - TMS9918
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template <Personality personality>
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void Base<personality>::draw_tms_character(int start, int end) {
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LineBuffer &line_buffer = line_buffers_[read_pointer_.row];
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// Paint the background tiles.
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const int pixels_left = end - start;
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if(this->screen_mode_ == ScreenMode::MultiColour) {
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for(int c = start; c < end; ++c) {
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pixel_target_[c] = palette[
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(line_buffer.patterns[c >> 3][0] >> (((c & 4)^4))) & 15
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];
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}
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} else {
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const int shift = start & 7;
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int byte_column = start >> 3;
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int length = std::min(pixels_left, 8 - shift);
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int pattern = Numeric::bit_reverse(line_buffer.patterns[byte_column][0]) >> shift;
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uint8_t colour = line_buffer.patterns[byte_column][1];
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uint32_t colours[2] = {
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palette[(colour & 15) ? (colour & 15) : background_colour_],
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palette[(colour >> 4) ? (colour >> 4) : background_colour_]
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};
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int background_pixels_left = pixels_left;
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while(true) {
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background_pixels_left -= length;
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for(int c = 0; c < length; ++c) {
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pixel_target_[c] = colours[pattern&0x01];
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pattern >>= 1;
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}
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pixel_target_ += length;
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if(!background_pixels_left) break;
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length = std::min(8, background_pixels_left);
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byte_column++;
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pattern = Numeric::bit_reverse(line_buffer.patterns[byte_column][0]);
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colour = line_buffer.patterns[byte_column][1];
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colours[0] = palette[(colour & 15) ? (colour & 15) : background_colour_];
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colours[1] = palette[(colour >> 4) ? (colour >> 4) : background_colour_];
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}
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}
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// Paint sprites and check for collisions, but only if at least one sprite is active
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// on this line.
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if(line_buffer.active_sprite_slot) {
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const int shift_advance = sprites_magnified_ ? 1 : 2;
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// If this is the start of the line clip any part of any sprites that is off to the left.
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if(!start) {
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for(int index = 0; index < line_buffer.active_sprite_slot; ++index) {
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LineBuffer::ActiveSprite &sprite = line_buffer.active_sprites[index];
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if(sprite.x < 0) sprite.shift_position -= shift_advance * sprite.x;
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}
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}
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int sprite_buffer[256];
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int sprite_collision = 0;
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memset(&sprite_buffer[start], 0, size_t(end - start)*sizeof(sprite_buffer[0]));
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constexpr uint32_t sprite_colour_selection_masks[2] = {0x00000000, 0xffffffff};
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constexpr int colour_masks[16] = {0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
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// Draw all sprites into the sprite buffer.
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const int shifter_target = sprites_16x16_ ? 32 : 16;
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for(int index = line_buffer.active_sprite_slot - 1; index >= 0; --index) {
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LineBuffer::ActiveSprite &sprite = line_buffer.active_sprites[index];
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if(sprite.shift_position < shifter_target) {
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const int pixel_start = std::max(start, sprite.x);
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for(int c = pixel_start; c < end && sprite.shift_position < shifter_target; ++c) {
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const int shift = (sprite.shift_position >> 1) ^ 7;
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int sprite_colour = (sprite.image[shift >> 3] >> (shift & 7)) & 1;
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// A colision is detected regardless of sprite colour ...
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sprite_collision |= sprite_buffer[c] & sprite_colour;
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sprite_buffer[c] |= sprite_colour;
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// ... but a sprite with the transparent colour won't actually be visible.
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sprite_colour &= colour_masks[sprite.image[2]&15];
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pixel_origin_[c] =
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(pixel_origin_[c] & sprite_colour_selection_masks[sprite_colour^1]) |
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(palette[sprite.image[2]&15] & sprite_colour_selection_masks[sprite_colour]);
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sprite.shift_position += shift_advance;
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}
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}
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}
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status_ |= sprite_collision << StatusSpriteCollisionShift;
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}
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}
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template <Personality personality>
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void Base<personality>::draw_tms_text(int start, int end) {
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LineBuffer &line_buffer = line_buffers_[read_pointer_.row];
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const uint32_t colours[2] = { palette[background_colour_], palette[text_colour_] };
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const int shift = start % 6;
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int byte_column = start / 6;
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int pattern = Numeric::bit_reverse(line_buffer.patterns[byte_column][0]) >> shift;
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int pixels_left = end - start;
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int length = std::min(pixels_left, 6 - shift);
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while(true) {
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pixels_left -= length;
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for(int c = 0; c < length; ++c) {
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pixel_target_[c] = colours[pattern&0x01];
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pattern >>= 1;
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}
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pixel_target_ += length;
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if(!pixels_left) break;
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length = std::min(6, pixels_left);
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byte_column++;
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pattern = Numeric::bit_reverse(line_buffer.patterns[byte_column][0]);
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}
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}
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// MARK: - Master System
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template <Personality personality>
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void Base<personality>::draw_sms(int start, int end, uint32_t cram_dot) {
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LineBuffer &line_buffer = line_buffers_[read_pointer_.row];
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int colour_buffer[256];
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/*
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Add extra border for any pixels that fall before the fine scroll.
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*/
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int tile_start = start, tile_end = end;
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int tile_offset = start;
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if(read_pointer_.row >= 16 || !master_system_.horizontal_scroll_lock) {
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for(int c = start; c < (line_buffer.latched_horizontal_scroll & 7); ++c) {
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colour_buffer[c] = 16 + background_colour_;
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++tile_offset;
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}
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// Remove the border area from that to which tiles will be drawn.
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tile_start = std::max(start - (line_buffer.latched_horizontal_scroll & 7), 0);
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tile_end = std::max(end - (line_buffer.latched_horizontal_scroll & 7), 0);
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}
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uint32_t pattern;
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uint8_t *const pattern_index = reinterpret_cast<uint8_t *>(&pattern);
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/*
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Add background tiles; these will fill the colour_buffer with values in which
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the low five bits are a palette index, and bit six is set if this tile has
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priority over sprites.
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*/
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if(tile_start < end) {
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const int shift = tile_start & 7;
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int byte_column = tile_start >> 3;
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int pixels_left = tile_end - tile_start;
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int length = std::min(pixels_left, 8 - shift);
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pattern = *reinterpret_cast<const uint32_t *>(line_buffer.patterns[byte_column]);
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if(line_buffer.names[byte_column].flags&2)
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pattern >>= shift;
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else
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pattern <<= shift;
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while(true) {
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const int palette_offset = (line_buffer.names[byte_column].flags&0x18) << 1;
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if(line_buffer.names[byte_column].flags&2) {
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for(int c = 0; c < length; ++c) {
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colour_buffer[tile_offset] =
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((pattern_index[3] & 0x01) << 3) |
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((pattern_index[2] & 0x01) << 2) |
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((pattern_index[1] & 0x01) << 1) |
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((pattern_index[0] & 0x01) << 0) |
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palette_offset;
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++tile_offset;
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pattern >>= 1;
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}
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} else {
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for(int c = 0; c < length; ++c) {
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colour_buffer[tile_offset] =
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((pattern_index[3] & 0x80) >> 4) |
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((pattern_index[2] & 0x80) >> 5) |
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((pattern_index[1] & 0x80) >> 6) |
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((pattern_index[0] & 0x80) >> 7) |
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palette_offset;
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++tile_offset;
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pattern <<= 1;
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}
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}
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pixels_left -= length;
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if(!pixels_left) break;
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length = std::min(8, pixels_left);
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byte_column++;
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pattern = *reinterpret_cast<const uint32_t *>(line_buffer.patterns[byte_column]);
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}
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}
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/*
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Apply sprites (if any).
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*/
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if(line_buffer.active_sprite_slot) {
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const int shift_advance = sprites_magnified_ ? 1 : 2;
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// If this is the start of the line clip any part of any sprites that is off to the left.
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if(!start) {
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for(int index = 0; index < line_buffer.active_sprite_slot; ++index) {
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LineBuffer::ActiveSprite &sprite = line_buffer.active_sprites[index];
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if(sprite.x < 0) sprite.shift_position -= shift_advance * sprite.x;
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}
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}
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int sprite_buffer[256];
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int sprite_collision = 0;
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memset(&sprite_buffer[start], 0, size_t(end - start)*sizeof(sprite_buffer[0]));
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// Draw all sprites into the sprite buffer.
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for(int index = line_buffer.active_sprite_slot - 1; index >= 0; --index) {
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LineBuffer::ActiveSprite &sprite = line_buffer.active_sprites[index];
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if(sprite.shift_position < 16) {
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const int pixel_start = std::max(start, sprite.x);
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// TODO: it feels like the work below should be simplifiable;
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// the double shift in particular, and hopefully the variable shift.
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for(int c = pixel_start; c < end && sprite.shift_position < 16; ++c) {
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const int shift = (sprite.shift_position >> 1);
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const int sprite_colour =
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(((sprite.image[3] << shift) & 0x80) >> 4) |
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(((sprite.image[2] << shift) & 0x80) >> 5) |
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(((sprite.image[1] << shift) & 0x80) >> 6) |
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(((sprite.image[0] << shift) & 0x80) >> 7);
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if(sprite_colour) {
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sprite_collision |= sprite_buffer[c];
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sprite_buffer[c] = sprite_colour | 0x10;
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}
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sprite.shift_position += shift_advance;
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}
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}
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}
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// Draw the sprite buffer onto the colour buffer, wherever the tile map doesn't have
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// priority (or is transparent).
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for(int c = start; c < end; ++c) {
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if(
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sprite_buffer[c] &&
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(!(colour_buffer[c]&0x20) || !(colour_buffer[c]&0xf))
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) colour_buffer[c] = sprite_buffer[c];
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}
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if(sprite_collision)
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status_ |= StatusSpriteCollision;
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}
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// Map from the 32-colour buffer to real output pixels, applying the specific CRAM dot if any.
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pixel_target_[start] = master_system_.colour_ram[colour_buffer[start] & 0x1f] | cram_dot;
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for(int c = start+1; c < end; ++c) {
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pixel_target_[c] = master_system_.colour_ram[colour_buffer[c] & 0x1f];
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}
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// If the VDP is set to hide the left column and this is the final call that'll come
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// this line, hide it.
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if(end == 256) {
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if(master_system_.hide_left_column) {
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pixel_origin_[0] = pixel_origin_[1] = pixel_origin_[2] = pixel_origin_[3] =
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pixel_origin_[4] = pixel_origin_[5] = pixel_origin_[6] = pixel_origin_[7] =
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master_system_.colour_ram[16 + background_colour_];
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}
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}
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}
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// MARK: - Yamaha
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// TODO.
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// MARK: - Mega Drive
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// TODO.
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#endif /* Draw_hpp */
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