Tilesets

The grid

:set editor tileset puts a grid over the picture in the window. The cursor is one cell of it, a dashed rectangle the size of a tile, starting at pixel 0,0. Esc takes the grid away again, and so does :set editor image; bare :set editor says which is up.

tiles.png The grid 1 / 4 play

1. start The sheet at 2x, no grid yet. Its tiles are 32 pixels and the default grid is 16, so the pitch has to be said before the cursor means anything.
2. 1 :tool tileset size 32Enter:set editor tilesetEnter The pitch, then the grid. The cursor is one tile of it, and the status row confirms both — 32×32 tile 0,0 of 8×8.
3. 2 llj hjkl move a tile at a time; counts multiply.
4. 3 :tool tileset select 2,2Enter select makes the cursor a block — yy, dd, p and r now act on all four tiles at once.

:tool tileset size 16,16          one tile, in pixels; the default
:tool tileset size 16             square, the same thing
:tool tileset kind tile           the only kind built — `hex` parses and is refused
:tool tileset select 3,3          the cursor becomes a block of tiles
:tool tileset image resize 32,32  the canvas, in tiles
:tool tileset image grow 1,1      that many tiles more

Each setting without a value reports it: :tool tileset size answers tileset size=16,16. Pairs take a comma — 16x16 is refused with not a pair: 16x16 (want 16 or 16,16).

Say the size first. Sixteen pixels is only the default, and a grid at the wrong pitch puts every cursor across four quarter-tiles. On a 32-pixel sheet the session starts :tool tileset size 32, and the status row is where you check it: it carries the tile size and the grid it makes — 256×256 2x 32×32 tile 0,0 of 8×8 — beside the file name.

The grid is always there. The image carries its tileset — size, kind, selection, cursor and undo history — from the moment it opens, and :set editor tileset only puts it on screen. So :tool tileset size 8 works before the grid is on, and Esc throws no history away: u after coming back still undoes what you did before you left.

Moving tiles

tiles.png Moving tiles 1 / 5 play

1. start The grid at 32 pixels, the cursor on the flagstone tile in the corner.
2. 1 dd dd cuts the tile into the slot and leaves transparency behind.
3. 2 lljj Move two tiles along and two down.
4. 3 p p puts it back down with its top-left at the cursor.
5. 4 u u undoes the paste; the tileset keeps its own history.

dd here and p there moves a tile, which is the operation a sheet wants most. Clearing means transparent: the sheet is RGBA in memory whatever it was on disk. p with an empty slot says nothing to paste, and a paste that would run past the sheet is refused rather than clipped — 96×96 does not fit at 6,6 — because a clipped paste is a guess about which corner you meant.

Turning a tile

r in a picture has no character to replace, so it means turn, and the key after it is a fresh lookup in the normal keymap — a rebound j turns the way j moves, and the arrows turn too.

tiles.png Turning a tile 1 / 4 play

1. start The cursor on the open door, two rows down.
2. 1 rj r means turn: rj takes it half way round.
3. 2 rx rx mirrors it left to right.
4. 3 rh rh is a quarter turn left. Every turn is one undo step.

A quarter turn of a block that is not square does not fit where it came from, so rh and rl are refused there — 16×8 does not turn — while the half turn and the mirrors work at any size. Every turn is one undo step. Any other key after r says rotate what? (r + h j k l x y).

Blocks and the canvas

:tool tileset select 3,3 makes the cursor three tiles wide and three tall. yy, dd, p and r then act on the whole block — a 96×96 yank from 32-pixel tiles — while hjkl still step one tile, and the block stops where the grid does.

tiles.png A block, moved and turned 1 / 7 play

1. start The grid at 32 pixels, the cursor one tile of it in the top-left corner.
2. 1 :tool tileset select 2,2Enter select makes the cursor a block. yy, dd, p and r act on all four tiles from here, while hjkl still step one tile at a time.
3. 2 dd dd cuts the block into the slot and leaves transparency behind — a 64×64 yank from 32-pixel tiles.
4. 3 lljjjj Two tiles along and four down. The block stops where the grid does, so it cannot walk off the sheet.
5. 4 p p puts the block down with its top-left at the cursor. A paste that would run past the edge is refused by size rather than clipped — a clipped paste is a guess about which corner you meant.
6. 5 rx r means turn, and rx mirrors the block left to right. rh and rl are quarter turns, rj half way round, ry a mirror top to bottom.
7. 6 u×3 Three undos: the mirror, the paste, the cut. Each was one step on the picture’s own history, and the sheet on disk was never touched — :w is what writes it.

image resize 32,32 makes the sheet thirty-two tiles a side: the pixels it had stay at the top-left, new room is transparent, anything past the new edge is cropped. image grow 1,1 adds a tile’s worth to the right and the bottom of the size it has in pixels, so a ragged edge stays ragged. Both are one undo step that brings every cropped pixel back.

Whole tiles only. A 100×100 sheet with 16-pixel tiles is a 6×6 grid; the four-pixel remainder is not a tile, the cursor never reaches it, and :w writes it back untouched. image grow is how it becomes a tile.

Saving

:w writes the sheet to its own file, as png. The mode changes nothing about that: : still opens the ex line, Ctrl-W still moves between windows, and the grid is a way of looking at the picture rather than a mode you are stuck in.