drinkingtea/nostalgia
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[nostalgia/core] Add functions for mapping tile idx to subsheet

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This commit is contained in:
Gary Talent 2024-01-27 23:52:40 -06:00
parent 1cf09433e8
commit caa59f3724
2 changed files with 44 additions and 0 deletions
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6
src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp
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@ -158,6 +158,12 @@ struct TileSheet {
[[nodiscard]]
std::size_t idx(TileSheet::SubSheet const&ss, ox::Point const&pt) noexcept;
[[nodiscard]]
TileSheet::SubSheet const*getSubsheet(TileSheet const&ts, SubSheetId const id) noexcept;
[[nodiscard]]
size_t getTileIdx(TileSheet const&ts, SubSheetId id) noexcept;
[[nodiscard]]
uint8_t getPixel4Bpp(TileSheet::SubSheet const&ss, std::size_t idx) noexcept;

38
src/nostalgia/modules/core/src/tilesheet.cpp
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@ -14,6 +14,44 @@ std::size_t idx(TileSheet::SubSheet const&ss, ox::Point const&pt) noexcept {
return ptToIdx(pt, ss.columns);
}
static TileSheet::SubSheet const*getSubsheet(TileSheet::SubSheet const&ss, SubSheetId const id) noexcept {
if (ss.id == id) {
return &ss;
}
for (auto const&child : ss.subsheets) {
if (auto out = getSubsheet(child, id)) {
return out;
}
}
return {};
}
TileSheet::SubSheet const*getSubsheet(TileSheet const&ts, SubSheetId const id) noexcept {
return getSubsheet(ts.subsheet, id);
}
static ox::Optional<size_t> getPixelIdx(
TileSheet::SubSheet const&ss,
SubSheetId const id,
size_t idx,
int8_t const bpp) noexcept {
for (auto const&child : ss.subsheets) {
if (child.id == id) {
return ox::Optional<size_t>(ox::in_place, idx);
}
if (auto out = getPixelIdx(child, id, idx, bpp)) {
return out;
}
idx += pixelCnt(ss, bpp);
}
return {};
}
size_t getTileIdx(TileSheet const&ts, SubSheetId const id) noexcept {
auto const out = getPixelIdx(ts.subsheet, id, 0, ts.bpp);
return out.or_value(0) / PixelsPerTile;
}
uint8_t getPixel4Bpp(TileSheet::SubSheet const&ss, std::size_t idx) noexcept {
if (idx & 1) {
return ss.pixels[idx / 2] >> 4;