335 lines
11 KiB
Text
335 lines
11 KiB
Text
== Tiles and Text
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Declared in `<joey/tile.h>`.
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A tile is not a separate object. It is the 8x8 region of a surface at block
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coordinates `(bx, by)`, where `bx` runs 0..39 and `by` runs 0..24 -- 40x25
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blocks across a 320x200 surface. The tile API moves 32-byte blocks between
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surfaces or fills them.
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The consequence is that everything else works on tiles too. You can paint tile
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content with `jlDrawPixel` and `jlFillRect`, generate it procedurally, or edit
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it at run time, because a "tileset" is just a surface you agree to treat as
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one. Fonts, terrain sets, and spritesheets are all the same thing.
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=== Constants and Types
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[cols="3,1,4", options="header"]
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|===
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|Name |Value |Meaning
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|`JL_TILE_PIXELS_PER_SIDE` |8 |Tile edge in pixels.
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|`JL_TILE_BYTES_PER_ROW` |4 |Bytes per tile row (8 pixels at 4bpp).
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|`JL_TILE_BYTES` |32 |Bytes in one tile.
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|`JL_TILE_BLOCKS_PER_ROW` |40 |Tile columns on a surface.
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|`JL_TILE_BLOCKS_PER_COL` |25 |Tile rows on a surface.
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|`JL_TILE_NO_GLYPH` |0xFFFF |`jlDrawText` map entry meaning "skip this character".
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|`JL_TILE_MAP_SKIP` |0xFF |`jlTileMapPaste` entry meaning "leave this cell alone".
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|===
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[source,c]
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----
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typedef struct jlTileT {
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uint8_t pixels[JL_TILE_BYTES];
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} jlTileT;
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----
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A stack-allocatable 32-byte tile snapshot, so save-under style work does not
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need a whole scratch surface.
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[IMPORTANT]
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====
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A `jlTileT` is *target-native*: plane-major on the Amiga and X68000, row by row
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with each row's four plane bytes together on the ST, and chunky on the others.
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Treat it as opaque. In particular, do not feed a tile from `jlTileSnap` or
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`jlTileBankLoad` to `jlTilePasteMono`, which wants a chunky silhouette -- on the
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Amiga, ST, and X68000 that is a format mismatch and draws the wrong shape. Use
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`jlTilePasteGlyph` for 1-bit glyph data instead.
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====
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=== jlTileCopy
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[source,c]
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----
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void jlTileCopy(jlSurfaceT *dst, uint8_t dstBx, uint8_t dstBy,
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const jlSurfaceT *src, uint8_t srcBx, uint8_t srcBy);
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----
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Copies one 8x8 block between surfaces, opaquely.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`dst` |`jlSurfaceT *` |Destination surface.
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|`dstBx`, `dstBy` |`uint8_t` |Destination block coordinates.
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|`src` |`const jlSurfaceT *` |Source surface. May be the same as `dst`.
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|`srcBx`, `srcBy` |`uint8_t` |Source block coordinates.
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|===
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*Returns:* nothing. Out-of-range block coordinates on either side are silent
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no-ops.
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=== jlTileCopyMasked
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[source,c]
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----
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void jlTileCopyMasked(jlSurfaceT *dst, uint8_t dstBx, uint8_t dstBy,
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const jlSurfaceT *src, uint8_t srcBx, uint8_t srcBy,
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uint8_t transparentIndex);
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----
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As `jlTileCopy`, but source pixels equal to `transparentIndex` are skipped and
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the destination keeps its original value. This is the call for fonts and for
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any tileset with see-through pixels.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`dst` |`jlSurfaceT *` |Destination surface.
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|`dstBx`, `dstBy` |`uint8_t` |Destination block coordinates.
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|`src` |`const jlSurfaceT *` |Source surface.
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|`srcBx`, `srcBy` |`uint8_t` |Source block coordinates.
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|`transparentIndex` |`uint8_t` |Source colour index treated as transparent.
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|===
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*Returns:* nothing.
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=== jlTileFill
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[source,c]
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----
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void jlTileFill(jlSurfaceT *s, uint8_t bx, uint8_t by, uint8_t colorIndex);
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----
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Fills one block with a solid colour. Equivalent to
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`jlFillRect(s, bx*8, by*8, 8, 8, colorIndex)` but skips the clipping maths,
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since block coordinates are already known to be in range.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`s` |`jlSurfaceT *` |Target surface.
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|`bx`, `by` |`uint8_t` |Block coordinates.
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|`colorIndex` |`uint8_t` |Colour index 0..15.
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|===
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*Returns:* nothing.
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=== jlTileBankLoad
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[source,c]
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----
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uint16_t jlTileBankLoad(const char *path, jlTileT *outTiles, uint16_t maxTiles,
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bool *outValid, uint16_t *outPalette);
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----
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Loads tiles from a baked `.tbk` file. The file's per-target byte is checked
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against the build platform and mismatches are refused.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`path` |`const char *` |File path.
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|`outTiles` |`jlTileT *` |Receives the tiles. Caller-owned.
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|`maxTiles` |`uint16_t` |Capacity of `outTiles`.
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|`outValid` |`bool *` |Optional, may be `NULL`. One flag per slot up to
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`maxTiles`: `true` for each loaded tile, `false` for the rest (all of them when
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the file is refused), so loaded tiles can be told from leftovers in a
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fixed-size array.
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|`outPalette` |`uint16_t *` |Optional, may be `NULL`. Receives the embedded
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16-entry `$0RGB` palette if the file has one.
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|===
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*Returns:* the number of tiles written. Returns 0 if the file is missing, the
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magic or target byte is wrong, or `maxTiles` is 0.
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=== jlTileBankLoadToSurface
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[source,c]
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----
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uint16_t jlTileBankLoadToSurface(const char *path, jlSurfaceT *dst,
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uint16_t *outPalette);
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----
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Streams a baked `.tbk` straight onto a surface's block grid: tile `i` lands at
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block `(i % 40, i / 40)`, the row-major layout the bake tools author against.
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Use this instead of `jlTileBankLoad` for anything large. A 1000-tile font sheet
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is 32000 bytes, which no IIgs program can hold in an array or in bank-0 BSS;
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this needs only a small internal scratch buffer and one pass over the file.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`path` |`const char *` |File path.
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|`dst` |`jlSurfaceT *` |Destination surface.
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|`outPalette` |`uint16_t *` |Optional, may be `NULL`. As `jlTileBankLoad`.
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|===
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*Returns:* the number of tiles pasted. Blocks beyond the file's tile count keep
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their previous content, and tiles past the surface's 1000 blocks are ignored.
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=== jlTileSnap
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[source,c]
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----
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void jlTileSnap(const jlSurfaceT *src, uint8_t bx, uint8_t by, jlTileT *out);
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----
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Captures one block into a caller-supplied `jlTileT`.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`src` |`const jlSurfaceT *` |Source surface.
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|`bx`, `by` |`uint8_t` |Block coordinates.
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|`out` |`jlTileT *` |Receives the 32-byte snapshot.
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|===
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*Returns:* nothing.
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=== jlTilePaste
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[source,c]
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----
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void jlTilePaste(jlSurfaceT *dst, uint8_t bx, uint8_t by, const jlTileT *in);
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----
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Pastes a `jlTileT` back onto a surface, always opaquely. Use
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`jlTileCopyMasked` if you need transparency.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`dst` |`jlSurfaceT *` |Destination surface.
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|`bx`, `by` |`uint8_t` |Block coordinates.
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|`in` |`const jlTileT *` |Tile to paste.
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|===
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*Returns:* nothing.
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=== jlTilePasteMono
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[source,c]
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----
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void jlTilePasteMono(jlSurfaceT *dst, uint8_t bx, uint8_t by,
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const jlTileT *in, uint8_t fgColor, uint8_t bgColor);
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----
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Pastes a tile as a silhouette: any non-zero source pixel draws `fgColor`, zero
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pixels draw `bgColor`. Useful when the bitmap is a fixed glyph but the colour
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comes from a separate map, as in C64-style colour RAM. Opaque.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`dst` |`jlSurfaceT *` |Destination surface.
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|`bx`, `by` |`uint8_t` |Block coordinates.
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|`in` |`const jlTileT *` |Source tile, read as a silhouette.
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|`fgColor` |`uint8_t` |Colour for non-zero pixels. Masked to 4 bits.
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|`bgColor` |`uint8_t` |Colour for zero pixels. Masked to 4 bits.
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|===
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*Returns:* nothing.
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[WARNING]
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====
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This call wants a *chunky* silhouette, but a `jlTileT` from `jlTileSnap` or
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`jlTileBankLoad` is target-native. Feeding one to this function on the Amiga,
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ST, or X68000 is a format mismatch. For glyphs, use `jlTilePasteGlyph`, which
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takes unambiguous 1-bit input.
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====
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=== jlTilePasteGlyph
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[source,c]
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----
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void jlTilePasteGlyph(jlSurfaceT *dst, uint8_t bx, uint8_t by,
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const uint8_t *bits, uint8_t fgColor, uint8_t bgColor);
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----
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Pastes an 8x8 one-bit-per-pixel glyph: `bits[row]` is that row, most
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significant bit leftmost. A set bit draws `fgColor`, a clear bit `bgColor`.
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Opaque.
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This is the shape a character generator already has -- a font ROM, a C64
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charset, anything 1bpp -- so nothing needs expanding into a `jlTileT` first.
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*Prefer this over `jlTilePasteMono` for glyphs.*
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`dst` |`jlSurfaceT *` |Destination surface.
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|`bx`, `by` |`uint8_t` |Block coordinates.
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|`bits` |`const uint8_t *` |8 bytes, one per glyph row, MSB leftmost.
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|`fgColor` |`uint8_t` |Set-bit colour. Masked to 4 bits.
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|`bgColor` |`uint8_t` |Clear-bit colour. Masked to 4 bits.
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|===
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*Returns:* nothing.
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=== jlDrawText
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[source,c]
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----
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void jlDrawText(jlSurfaceT *dst, uint8_t bx, uint8_t by,
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const jlSurfaceT *fontSurface, const uint16_t *asciiMap,
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const char *str);
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----
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Draws a NUL-terminated ASCII string using glyphs from a font surface. Glyph
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colour 0 is transparent, so the background shows through. The cursor wraps at
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the right edge and truncates at the bottom. A start off the 40x25 grid uses up
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characters without drawing them as the cursor moves on: a start column past
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39 drops the first character and carries on at the start of the next row, and
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a start row past 24 draws nothing.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`dst` |`jlSurfaceT *` |Destination surface.
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|`bx`, `by` |`uint8_t` |Starting block coordinates.
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|`fontSurface` |`const jlSurfaceT *` |Surface holding the glyphs.
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|`asciiMap` |`const uint16_t *` |256 entries mapping ASCII code to glyph
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position: low byte is source block X, high byte is source block Y. An entry of
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`JL_TILE_NO_GLYPH`, or one off the font surface's 40x25 grid, skips that
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character, advancing the cursor without drawing.
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|`str` |`const char *` |NUL-terminated string.
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|===
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*Returns:* nothing.
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=== jlTileMapPaste
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[source,c]
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----
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void jlTileMapPaste(jlSurfaceT *dst, uint8_t bx, uint8_t by,
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uint8_t wTiles, uint8_t hTiles,
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const jlTileT *tiles, const uint8_t *map);
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----
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Pastes a whole rectangle of tiles in one call, so validation, dispatch, and the
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dirty-rectangle union are paid once for the rectangle instead of once per tile.
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For anything larger than a few tiles this is substantially faster than looping
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over `jlTilePaste`.
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[cols="1,1,4", options="header"]
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|===
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|Parameter |Type |Description
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|`dst` |`jlSurfaceT *` |Destination surface.
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|`bx`, `by` |`uint8_t` |Top-left block coordinates.
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|`wTiles`, `hTiles` |`uint8_t` |Rectangle size in tiles. Zero is a no-op.
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|`tiles` |`const jlTileT *` |The tileset.
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|`map` |`const uint8_t *` |`wTiles * hTiles` tileset indices, row-major, so
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`map[row * wTiles + col]`. `JL_TILE_MAP_SKIP` leaves that cell untouched.
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|===
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*Returns:* nothing. A rectangle whose edge crosses the surface boundary is
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rejected as a no-op.
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[WARNING]
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====
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Any map index other than `JL_TILE_MAP_SKIP` must be a valid tileset index. The
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batch does not know the tileset length and does *not* range-check it -- an
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out-of-range index reads past the end of your array.
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====
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