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Helper functions for ImpactJS to double or halve the tilesize of a BackgroundMap (without breaking their appearance)
export function halveTilesize( layer: Layer, tileset: Image ) {
if( layer.tilesize % 2 !== 0 || (layer.name !== 'collision' && !tileset.loaded) ) {
return false;
}
const oldTileWidth = tileset.width / layer.tilesize;
const newTileWidth = (tileset.width / layer.tilesize) * 2;
const newData = [];
for( let y = 0; y < layer.height; y++ ) {
newData[y * 2] = [];
newData[y * 2 + 1] = [];
for( let x = 0; x < layer.width; x++ ) {
const oldTile = layer.data[y][x] - 1;
if( oldTile === -1 ) { // Empty tile
newData[y * 2][x * 2] = 0;
newData[y * 2][x * 2 + 1] = 0;
newData[y * 2 + 1][x * 2] = 0;
newData[y * 2 + 1][x * 2 + 1] = 0;
} else {
let a: number, b: number, c: number, d: number;
if (layer.name === 'collision') {
a = b = c = d = oldTile + 1;
} else {
const oldTilesetY = Math.floor(oldTile / oldTileWidth);
const oldTilesetX = oldTile - oldTilesetY * oldTileWidth;
const newTilesetX = oldTilesetX * 2;
const newTilesetY = oldTilesetY * 2;
a = (newTilesetY + 0) * newTileWidth + (newTilesetX + 0) + 1;
b = (newTilesetY + 0) * newTileWidth + (newTilesetX + 1) + 1;
c = (newTilesetY + 1) * newTileWidth + (newTilesetX + 0) + 1;
d = (newTilesetY + 1) * newTileWidth + (newTilesetX + 1) + 1;
}
newData[y * 2][x * 2] = a;
newData[y * 2][x * 2 + 1] = b;
newData[y * 2 + 1][x * 2] = c;
newData[y * 2 + 1][x * 2 + 1] = d;
}
}
}
layer.tilesize /= 2;
layer.width *= 2;
layer.height *= 2;
layer.data = newData;
return true;
}
export function doubleTilesize( layer: Layer, tileset: Image ) {
if( layer.width % 2 !== 0 || layer.height % 2 !== 0 || (layer.name !== 'collision' && !tileset.loaded) ) {
return false;
}
const oldTileWidth = tileset.width / layer.tilesize;
const newTileWidth = (tileset.width / layer.tilesize) / 2;
if( newTileWidth % 1 !== 0 ) {
return false;
}
const newData = [];
for( let y = 0; y < layer.height; y += 2 ) {
newData[y / 2] = [];
for( let x = 0; x < layer.width; x += 2 ) {
const oldTile = layer.data[y][x] - 1;
if( oldTile === -1 ) { // Empty tile
newData[y / 2][x / 2] = 0;
} else {
if(layer.name === 'collision') {
newData[y / 2][x / 2] = oldTile + 1;
} else {
const oldTilesetY = Math.floor(oldTile / oldTileWidth);
const oldTilesetX = oldTile - oldTilesetY * oldTileWidth;
const newTilesetX = oldTilesetX / 2;
const newTilesetY = oldTilesetY / 2;
newData[y / 2][x / 2] = newTilesetY * newTileWidth + newTilesetX + 1;
}
}
}
}
layer.tilesize *= 2;
layer.width /= 2;
layer.height /= 2;
layer.data = newData;
return true;
}
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