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CLK/Components/9918/Implementation/Draw.hpp
2024-01-16 23:34:46 -05:00

570 lines
19 KiB
C++

//
// Draw.hpp
// Clock Signal
//
// Created by Thomas Harte on 05/01/2023.
// Copyright © 2023 Thomas Harte. All rights reserved.
//
#pragma once
namespace TI::TMS {
// MARK: - Sprites, as generalised.
template <Personality personality>
template <SpriteMode mode, bool double_width>
void Base<personality>::draw_sprites([[maybe_unused]] uint8_t y, int start, int end, const std::array<uint32_t, 16> &palette, int *colour_buffer) {
if(!draw_line_buffer_->sprites) {
return;
}
auto &buffer = *draw_line_buffer_->sprites;
if(!buffer.active_sprite_slot) {
return;
}
const int shift_advance = sprites_magnified_ ? 1 : 2;
// If this is the start of the line clip any part of any sprites that is off to the left.
if(!start) {
for(int index = 0; index < buffer.active_sprite_slot; ++index) {
auto &sprite = buffer.active_sprites[index];
if(sprite.x < 0) sprite.shift_position -= shift_advance * sprite.x;
}
}
int sprite_buffer[256];
int sprite_collision = 0;
memset(&sprite_buffer[start], 0, size_t(end - start)*sizeof(sprite_buffer[0]));
if constexpr (mode == SpriteMode::MasterSystem) {
// Draw all sprites into the sprite buffer.
for(int index = buffer.active_sprite_slot - 1; index >= 0; --index) {
auto &sprite = buffer.active_sprites[index];
if(sprite.shift_position >= 16) {
continue;
}
const int pixel_start = std::max(start, sprite.x);
// TODO: it feels like the work below should be simplifiable;
// the double shift in particular, and hopefully the variable shift.
for(int c = pixel_start; c < end && sprite.shift_position < 16; ++c) {
const int shift = (sprite.shift_position >> 1);
const int sprite_colour =
(((sprite.image[3] << shift) & 0x80) >> 4) |
(((sprite.image[2] << shift) & 0x80) >> 5) |
(((sprite.image[1] << shift) & 0x80) >> 6) |
(((sprite.image[0] << shift) & 0x80) >> 7);
if(sprite_colour) {
sprite_collision |= sprite_buffer[c];
sprite_buffer[c] = sprite_colour | 0x10;
}
sprite.shift_position += shift_advance;
}
}
// Draw the sprite buffer onto the colour buffer, wherever the tile map doesn't have
// priority (or is transparent).
for(int c = start; c < end; ++c) {
if(
sprite_buffer[c] &&
(!(colour_buffer[c]&0x20) || !(colour_buffer[c]&0xf))
) colour_buffer[c] = sprite_buffer[c];
}
if(sprite_collision) {
status_ |= StatusSpriteCollision;
}
return;
}
if constexpr (SpriteBuffer::test_is_filling) {
assert(!buffer.is_filling);
}
constexpr uint32_t sprite_colour_selection_masks[2] = {0x00000000, 0xffffffff};
constexpr int colour_masks[16] = {0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
const int sprite_width = sprites_16x16_ ? 16 : 8;
const int shifter_target = sprite_width << 1;
const int pixel_width = sprites_magnified_ ? sprite_width << 1 : sprite_width;
int min_sprite = 0;
//
// Approach taken for Mode 2 sprites:
//
// (1) precompute full sprite images, at up to 32 pixels wide;
// (2) for each sprite that is marked as CC, walk backwards until the
// first sprite that is not marked CC, ORing it into the precomputed
// image at each step;
// (3) subsequently, just draw each sprite image independently.
//
if constexpr (mode == SpriteMode::Mode2) {
// Determine the lowest visible sprite; exit early if that leaves no sprites visible.
for(; min_sprite < buffer.active_sprite_slot; min_sprite++) {
auto &sprite = buffer.active_sprites[min_sprite];
if(sprite.opaque()) {
break;
}
}
if(min_sprite == buffer.active_sprite_slot) {
return;
}
if(!start) {
// Pre-rasterise the sprites one-by-one.
if(sprites_magnified_) {
for(int index = min_sprite; index < buffer.active_sprite_slot; index++) {
auto &sprite = buffer.active_sprites[index];
for(int c = 0; c < 32; c+= 2) {
const int shift = (c >> 1) ^ 7;
const int bit = 1 & (sprite.image[shift >> 3] >> (shift & 7));
Storage<personality>::sprite_cache_[index][c] =
Storage<personality>::sprite_cache_[index][c + 1] =
(sprite.image[2] & 0xf & sprite_colour_selection_masks[bit]) |
uint8_t((bit << StatusSpriteCollisionShift) & sprite.collision_bit());
}
}
} else {
for(int index = min_sprite; index < buffer.active_sprite_slot; index++) {
auto &sprite = buffer.active_sprites[index];
for(int c = 0; c < 16; c++) {
const int shift = c ^ 7;
const int bit = 1 & (sprite.image[shift >> 3] >> (shift & 7));
Storage<personality>::sprite_cache_[index][c] =
(sprite.image[2] & 0xf & sprite_colour_selection_masks[bit]) |
uint8_t((bit << StatusSpriteCollisionShift) & sprite.collision_bit());
}
}
}
// Go backwards compositing any sprites that are set as OR masks onto their parents.
for(int index = buffer.active_sprite_slot - 1; index >= min_sprite + 1; --index) {
auto &sprite = buffer.active_sprites[index];
if(sprite.opaque()) {
continue;
}
// Sprite may affect all previous up to and cindlugin the next one that is opaque.
for(int previous_index = index - 1; previous_index >= min_sprite; --previous_index) {
// Determine region of overlap (if any).
auto &previous = buffer.active_sprites[previous_index];
const int origin = sprite.x - previous.x;
const int x1 = std::max(0, -origin);
const int x2 = std::min(pixel_width - origin, pixel_width);
// Composite sprites.
for(int x = x1; x < x2; x++) {
Storage<personality>::sprite_cache_[previous_index][x + origin]
|= Storage<personality>::sprite_cache_[index][x];
}
// If a previous opaque sprite has been found, stop.
if(previous.opaque()) {
break;
}
}
}
}
// Draw.
for(int index = buffer.active_sprite_slot - 1; index >= min_sprite; --index) {
auto &sprite = buffer.active_sprites[index];
const int x1 = std::max(0, start - sprite.x);
const int x2 = std::min(end - sprite.x, pixel_width);
for(int x = x1; x < x2; x++) {
const uint8_t colour = Storage<personality>::sprite_cache_[index][x];
// Plot colour, if visible.
if(colour) {
pixel_origin_[sprite.x + x] = palette[colour & 0xf];
}
// TODO: is collision location recorded in mode 1?
// Check for a new collision.
if(!(status_ & StatusSpriteCollision)) {
sprite_collision |= sprite_buffer[sprite.x + x];
sprite_buffer[sprite.x + x] |= colour;
status_ |= sprite_collision & StatusSpriteCollision;
if(status_ & StatusSpriteCollision) {
Storage<personality>::collision_location_[0] = uint16_t(x);
Storage<personality>::collision_location_[1] = uint16_t(y);
}
}
}
}
return;
}
if constexpr (mode == SpriteMode::Mode1) {
for(int index = buffer.active_sprite_slot - 1; index >= min_sprite; --index) {
auto &sprite = buffer.active_sprites[index];
if(sprite.shift_position >= shifter_target) {
continue;
}
const int pixel_start = std::max(start, sprite.x);
for(int c = pixel_start; c < end && sprite.shift_position < shifter_target; ++c) {
const int shift = (sprite.shift_position >> 1) ^ 7;
int sprite_colour = (sprite.image[shift >> 3] >> (shift & 7)) & 1;
// A colision is detected regardless of sprite colour ...
sprite_collision |= sprite_buffer[c] & sprite_colour;
sprite_buffer[c] |= sprite_colour;
// ... but a sprite with the transparent colour won't actually be visible.
sprite_colour &= colour_masks[sprite.image[2] & 0xf];
pixel_origin_[c] =
(pixel_origin_[c] & sprite_colour_selection_masks[sprite_colour^1]) |
(palette[sprite.image[2] & 0xf] & sprite_colour_selection_masks[sprite_colour]);
sprite.shift_position += shift_advance;
}
}
status_ |= sprite_collision << StatusSpriteCollisionShift;
return;
}
}
// Mode 2 logic, as I currently understand it, as a note for my future self:
//
// If a sprite is marked as 'CC' then it doesn't collide, but its colour value is
// ORd with those of all lower-numbered sprites down to the next one that is visible on
// that line and not marked CC.
//
// If no previous sprite meets that criteria, no pixels are displayed. But if one does
// then pixels are displayed even where they don't overlap with the earlier sprites.
//
// ... so in terms of my loop above, I guess I need temporary storage to accumulate
// an OR mask up until I hit a non-CC sprite, at which point I composite everything out?
// I'm not immediately sure whether I can appropriately reuse sprite_buffer, but possibly?
// MARK: - TMS9918
template <Personality personality>
template <SpriteMode sprite_mode>
void Base<personality>::draw_tms_character(int start, int end) {
auto &line_buffer = *draw_line_buffer_;
// Paint the background tiles.
const int pixels_left = end - start;
if(this->screen_mode_ == ScreenMode::MultiColour) {
for(int c = start; c < end; ++c) {
pixel_target_[c] = palette()[
(line_buffer.tiles.patterns[c >> 3][0] >> (((c & 4)^4))) & 15
];
}
} else {
const int shift = start & 7;
int byte_column = start >> 3;
int length = std::min(pixels_left, 8 - shift);
int pattern = Numeric::bit_reverse(line_buffer.tiles.patterns[byte_column][0]) >> shift;
uint8_t colour = line_buffer.tiles.patterns[byte_column][1];
uint32_t colours[2] = {
palette()[(colour & 15) ? (colour & 15) : background_colour_],
palette()[(colour >> 4) ? (colour >> 4) : background_colour_]
};
int background_pixels_left = pixels_left;
while(true) {
background_pixels_left -= length;
for(int c = 0; c < length; ++c) {
pixel_target_[c] = colours[pattern&0x01];
pattern >>= 1;
}
pixel_target_ += length;
if(!background_pixels_left) break;
length = std::min(8, background_pixels_left);
byte_column++;
pattern = Numeric::bit_reverse(line_buffer.tiles.patterns[byte_column][0]);
colour = line_buffer.tiles.patterns[byte_column][1];
colours[0] = palette()[(colour & 15) ? (colour & 15) : background_colour_];
colours[1] = palette()[(colour >> 4) ? (colour >> 4) : background_colour_];
}
}
draw_sprites<sprite_mode, false>(0, start, end, palette()); // TODO: propagate a real 'y' into here.
}
template <Personality personality>
template <bool apply_blink>
void Base<personality>::draw_tms_text(int start, int end) {
auto &line_buffer = *draw_line_buffer_;
uint32_t colours[2][2] = {
{palette()[background_colour_], palette()[text_colour_]},
{0, 0}
};
if constexpr (apply_blink) {
colours[1][0] = palette()[Storage<personality>::blink_background_colour_];
colours[1][1] = palette()[Storage<personality>::blink_text_colour_];
}
const int shift = start % 6;
int byte_column = start / 6;
int pattern = Numeric::bit_reverse(line_buffer.characters.shapes[byte_column]) >> shift;
int pixels_left = end - start;
int length = std::min(pixels_left, 6 - shift);
int flag = 0;
if constexpr (apply_blink) {
flag = (line_buffer.characters.flags[byte_column >> 3] >> ((byte_column & 7) ^ 7)) & Storage<personality>::in_blink_;
}
while(true) {
pixels_left -= length;
for(int c = 0; c < length; ++c) {
pixel_target_[c] = colours[flag][(pattern&0x01)];
pattern >>= 1;
}
pixel_target_ += length;
if(!pixels_left) break;
length = std::min(6, pixels_left);
byte_column++;
pattern = Numeric::bit_reverse(line_buffer.characters.shapes[byte_column]);
if constexpr (apply_blink) {
flag = (line_buffer.characters.flags[byte_column >> 3] >> ((byte_column & 7) ^ 7)) & Storage<personality>::in_blink_;
}
}
}
// MARK: - Master System
template <Personality personality>
void Base<personality>::draw_sms([[maybe_unused]] int start, [[maybe_unused]] int end, [[maybe_unused]] uint32_t cram_dot) {
if constexpr (is_sega_vdp(personality)) {
int colour_buffer[256];
auto &line_buffer = *draw_line_buffer_;
/*
Add extra border for any pixels that fall before the fine scroll.
*/
int tile_start = start, tile_end = end;
int tile_offset = start;
if(output_pointer_.row >= 16 || !Storage<personality>::horizontal_scroll_lock_) {
for(int c = start; c < (line_buffer.latched_horizontal_scroll & 7); ++c) {
colour_buffer[c] = 16 + background_colour_;
++tile_offset;
}
// Remove the border area from that to which tiles will be drawn.
tile_start = std::max(start - (line_buffer.latched_horizontal_scroll & 7), 0);
tile_end = std::max(end - (line_buffer.latched_horizontal_scroll & 7), 0);
}
uint32_t pattern;
uint8_t *const pattern_index = reinterpret_cast<uint8_t *>(&pattern);
/*
Add background tiles; these will fill the colour_buffer with values in which
the low five bits are a palette index, and bit six is set if this tile has
priority over sprites.
*/
if(tile_start < end) {
const int shift = tile_start & 7;
int byte_column = tile_start >> 3;
int pixels_left = tile_end - tile_start;
int length = std::min(pixels_left, 8 - shift);
pattern = *reinterpret_cast<const uint32_t *>(line_buffer.tiles.patterns[byte_column]);
if(line_buffer.tiles.flags[byte_column]&2)
pattern >>= shift;
else
pattern <<= shift;
while(true) {
const int palette_offset = (line_buffer.tiles.flags[byte_column]&0x18) << 1;
if(line_buffer.tiles.flags[byte_column]&2) {
for(int c = 0; c < length; ++c) {
colour_buffer[tile_offset] =
((pattern_index[3] & 0x01) << 3) |
((pattern_index[2] & 0x01) << 2) |
((pattern_index[1] & 0x01) << 1) |
((pattern_index[0] & 0x01) << 0) |
palette_offset;
++tile_offset;
pattern >>= 1;
}
} else {
for(int c = 0; c < length; ++c) {
colour_buffer[tile_offset] =
((pattern_index[3] & 0x80) >> 4) |
((pattern_index[2] & 0x80) >> 5) |
((pattern_index[1] & 0x80) >> 6) |
((pattern_index[0] & 0x80) >> 7) |
palette_offset;
++tile_offset;
pattern <<= 1;
}
}
pixels_left -= length;
if(!pixels_left) break;
length = std::min(8, pixels_left);
byte_column++;
pattern = *reinterpret_cast<const uint32_t *>(line_buffer.tiles.patterns[byte_column]);
}
}
/*
Apply sprites (if any).
*/
draw_sprites<SpriteMode::MasterSystem, false>(0, start, end, palette(), colour_buffer); // TODO provide good y, as per elsewhere.
// Map from the 32-colour buffer to real output pixels, applying the specific CRAM dot if any.
pixel_target_[start] = Storage<personality>::colour_ram_[colour_buffer[start] & 0x1f] | cram_dot;
for(int c = start+1; c < end; ++c) {
pixel_target_[c] = Storage<personality>::colour_ram_[colour_buffer[c] & 0x1f];
}
// If the VDP is set to hide the left column and this is the final call that'll come
// this line, hide it.
if(end == 256) {
if(Storage<personality>::hide_left_column_) {
pixel_origin_[0] = pixel_origin_[1] = pixel_origin_[2] = pixel_origin_[3] =
pixel_origin_[4] = pixel_origin_[5] = pixel_origin_[6] = pixel_origin_[7] =
Storage<personality>::colour_ram_[16 + background_colour_];
}
}
}
}
// MARK: - Yamaha
template <Personality personality>
template <ScreenMode mode>
void Base<personality>::draw_yamaha(uint8_t y, int start, int end) {
[[maybe_unused]] const auto active_palette = palette();
const int sprite_start = start >> 2;
const int sprite_end = end >> 2;
auto &line_buffer = *draw_line_buffer_;
// Observation justifying Duff's device below: it's acceptable to paint too many pixels — to paint
// beyond `end` — provided that the overpainting is within normal bitmap bounds, because any
// mispainted pixels will be replaced before becoming visible to the user.
if constexpr (mode == ScreenMode::YamahaGraphics4 || mode == ScreenMode::YamahaGraphics6) {
start >>= (mode == ScreenMode::YamahaGraphics4) ? 2 : 1;
end >>= (mode == ScreenMode::YamahaGraphics4) ? 2 : 1;
int column = start & ~1;
const int offset = start & 1;
start >>= 1;
end = (end + 1) >> 1;
switch(offset) {
case 0:
do {
pixel_target_[column+0] = active_palette[line_buffer.bitmap[start] >> 4]; [[fallthrough]];
case 1: pixel_target_[column+1] = active_palette[line_buffer.bitmap[start] & 0xf];
++start;
column += 2;
} while(start < end);
}
}
if constexpr (mode == ScreenMode::YamahaGraphics5) {
start >>= 1;
end >>= 1;
int column = start & ~3;
const int offset = start & 3;
start >>= 2;
end = (end + 3) >> 2;
switch(offset) {
case 0:
do {
pixel_target_[column+0] = active_palette[line_buffer.bitmap[start] >> 6]; [[fallthrough]];
case 1: pixel_target_[column+1] = active_palette[(line_buffer.bitmap[start] >> 4) & 3]; [[fallthrough]];
case 2: pixel_target_[column+2] = active_palette[(line_buffer.bitmap[start] >> 2) & 3]; [[fallthrough]];
case 3: pixel_target_[column+3] = active_palette[line_buffer.bitmap[start] & 3];
++start;
column += 4;
} while(start < end);
}
}
if constexpr (mode == ScreenMode::YamahaGraphics7) {
start >>= 2;
end >>= 2;
while(start < end) {
pixel_target_[start] =
palette_pack(
uint8_t((line_buffer.bitmap[start] & 0x1c) + ((line_buffer.bitmap[start] & 0x1c) << 3) + ((line_buffer.bitmap[start] & 0x1c) >> 3)),
uint8_t((line_buffer.bitmap[start] & 0xe0) + ((line_buffer.bitmap[start] & 0xe0) >> 3) + ((line_buffer.bitmap[start] & 0xe0) >> 6)),
uint8_t((line_buffer.bitmap[start] & 0x03) + ((line_buffer.bitmap[start] & 0x03) << 2) + ((line_buffer.bitmap[start] & 0x03) << 4) + ((line_buffer.bitmap[start] & 0x03) << 6))
);
++start;
}
}
constexpr std::array<uint32_t, 16> graphics7_sprite_palette = {
palette_pack(0b00000000, 0b00000000, 0b00000000), palette_pack(0b00000000, 0b00000000, 0b01001001),
palette_pack(0b00000000, 0b01101101, 0b00000000), palette_pack(0b00000000, 0b01101101, 0b01001001),
palette_pack(0b01101101, 0b00000000, 0b00000000), palette_pack(0b01101101, 0b00000000, 0b01001001),
palette_pack(0b01101101, 0b01101101, 0b00000000), palette_pack(0b01101101, 0b01101101, 0b01001001),
palette_pack(0b10010010, 0b11111111, 0b01001001), palette_pack(0b00000000, 0b00000000, 0b11111111),
palette_pack(0b00000000, 0b11111111, 0b00000000), palette_pack(0b00000000, 0b11111111, 0b11111111),
palette_pack(0b11111111, 0b00000000, 0b00000000), palette_pack(0b11111111, 0b00000000, 0b11111111),
palette_pack(0b11111111, 0b11111111, 0b00000000), palette_pack(0b11111111, 0b11111111, 0b11111111),
};
// Possibly TODO: is the data-sheet trying to allege some sort of colour mixing for sprites in Mode 6?
draw_sprites<
SpriteMode::Mode2,
mode == ScreenMode::YamahaGraphics5 || mode == ScreenMode::YamahaGraphics6
>(y, sprite_start, sprite_end, mode == ScreenMode::YamahaGraphics7 ? graphics7_sprite_palette : palette());
}
template <Personality personality>
void Base<personality>::draw_yamaha(uint8_t y, int start, int end) {
if constexpr (is_yamaha_vdp(personality)) {
switch(draw_line_buffer_->screen_mode) {
// Modes that are the same (or close enough) to those on the TMS.
case ScreenMode::Text: draw_tms_text<false>(start >> 2, end >> 2); break;
case ScreenMode::YamahaText80: draw_tms_text<true>(start >> 1, end >> 1); break;
case ScreenMode::MultiColour:
case ScreenMode::ColouredText:
case ScreenMode::Graphics: draw_tms_character(start >> 2, end >> 2); break;
case ScreenMode::YamahaGraphics3:
draw_tms_character<SpriteMode::Mode2>(start >> 2, end >> 2);
break;
#define Dispatch(x) case ScreenMode::x: draw_yamaha<ScreenMode::x>(y, start, end); break;
Dispatch(YamahaGraphics4);
Dispatch(YamahaGraphics5);
Dispatch(YamahaGraphics6);
Dispatch(YamahaGraphics7);
#undef Dispatch
default: break;
}
}
}
// MARK: - Mega Drive
// TODO.
}