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Take a shot at Mode 2 sprite output.

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This commit is contained in:
Thomas Harte 2023-02-25 08:48:16 -06:00
parent 2592dfd78f
commit 1bdf9a50e6
2 changed files with 135 additions and 38 deletions
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172
Components/9918/Implementation/Draw.hpp
View File

@ -36,26 +36,28 @@ void Base<personality>::draw_sprites(LineBuffer &buffer, int start, int end, int
// Draw all sprites into the sprite buffer.
for(int index = buffer.active_sprite_slot - 1; index >= 0; --index) {
LineBuffer::ActiveSprite &sprite = buffer.active_sprites[index];
if(sprite.shift_position < 16) {
const int pixel_start = std::max(start, sprite.x);
if(sprite.shift_position >= 16) {
continue;
}
// 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);
const int pixel_start = std::max(start, sprite.x);
if(sprite_colour) {
sprite_collision |= sprite_buffer[c];
sprite_buffer[c] = sprite_colour | 0x10;
}
// 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);
sprite.shift_position += shift_advance;
if(sprite_colour) {
sprite_collision |= sprite_buffer[c];
sprite_buffer[c] = sprite_colour | 0x10;
}
sprite.shift_position += shift_advance;
}
}
@ -76,31 +78,125 @@ void Base<personality>::draw_sprites(LineBuffer &buffer, int start, int end, int
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;
// TODO: real Mode 2 logic.
if constexpr (mode == SpriteMode::Mode1 || mode == SpriteMode::Mode2) {
// Draw all sprites into the sprite buffer.
const int shifter_target = sprites_16x16_ ? 32 : 16;
for(int index = buffer.active_sprite_slot - 1; index >= 0; --index) {
LineBuffer::ActiveSprite &sprite = buffer.active_sprites[index];
if(sprite.shift_position < shifter_target) {
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;
//
// 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++) {
LineBuffer::ActiveSprite &sprite = buffer.active_sprites[min_sprite];
if(!(sprite.image[2]&0x40)) {
break;
}
}
if(min_sprite == buffer.active_sprite_slot) {
return;
}
// 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]&15];
pixel_origin_[c] =
(pixel_origin_[c] & sprite_colour_selection_masks[sprite_colour^1]) |
(palette()[sprite.image[2]&15] & sprite_colour_selection_masks[sprite_colour]);
sprite.shift_position += shift_advance;
if(!start) {
// Pre-rasterise the sprites one-by-one.
if(sprites_magnified_) {
for(int index = min_sprite; index < buffer.active_sprite_slot; index++) {
LineBuffer::ActiveSprite &sprite = buffer.active_sprites[index];
for(int c = 0; c < 32; c+= 2) {
const int shift = (c >> 1) ^ 7;
Storage<personality>::sprite_cache_[index][c] = Storage<personality>::sprite_cache_[index][c + 1] =
sprite.image[2] & 0xf & sprite_colour_selection_masks[1 & (sprite.image[shift >> 3] >> (shift & 7))];
}
}
} else {
for(int index = min_sprite; index < buffer.active_sprite_slot; index++) {
LineBuffer::ActiveSprite &sprite = buffer.active_sprites[index];
for(int c = 0; c < 16; c++) {
const int shift = c ^ 7;
Storage<personality>::sprite_cache_[index][c] =
sprite.image[2] & 0xf & sprite_colour_selection_masks[1 & (sprite.image[shift >> 3] >> (shift & 7))];
}
}
}
// 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) {
LineBuffer::ActiveSprite &sprite = buffer.active_sprites[index];
if(!(sprite.image[2] & 0x40)) {
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).
LineBuffer::ActiveSprite &previous = buffer.active_sprites[previous_index];
const int origin = previous.x - sprite.x;
const int x1 = std::max(0, 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.image[2] & 0x40) {
break;
}
}
}
}
// Draw.
for(int index = buffer.active_sprite_slot - 1; index >= min_sprite; --index) {
LineBuffer::ActiveSprite &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];
if(colour) {
pixel_origin_[sprite.x + x] = palette()[colour];
}
}
// TODO: collisions.
}
return;
}
if constexpr (mode == SpriteMode::Mode1) {
for(int index = buffer.active_sprite_slot - 1; index >= min_sprite; --index) {
LineBuffer::ActiveSprite &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]&15];
pixel_origin_[c] =
(pixel_origin_[c] & sprite_colour_selection_masks[sprite_colour^1]) |
(palette()[sprite.image[2]&15] & sprite_colour_selection_masks[sprite_colour]);
sprite.shift_position += shift_advance;
}
}

1
Components/9918/Implementation/Storage.hpp
View File

@ -47,6 +47,7 @@ template <Personality personality> struct Storage<personality, std::enable_if_t<
uint8_t mode_ = 0;
uint8_t vertical_offset_ = 0;
uint8_t sprite_cache_[8][32]{};
/// Describes an _observable_ memory access event. i.e. anything that it is safe
/// (and convenient) to treat as atomic in between external slots.