70 lines
1.5 KiB
Plaintext
70 lines
1.5 KiB
Plaintext
function grid(w, h) {
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this.width = w;
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this.height = h;
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// create a height×width array of empty lists
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this.cells = new Array(h);
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for (let y = 0; y < h; y++) {
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this.cells[y] = new Array(w);
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for (let x = 0; x < w; x++) {
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this.cells[y][x] = []; // each cell holds its own list
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}
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}
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}
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grid.prototype = {
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// return the array at (x,y)
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cell(x, y) {
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return this.cells[y][x];
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},
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// alias for cell
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at(pos) {
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return this.cell(pos.x, pos.y);
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},
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// add an entity into a cell
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add(entity, pos) {
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this.cell(pos.x, pos.y).push(entity);
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entity.coord = pos.slice();
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},
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// remove an entity from a cell
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remove(entity, pos) {
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const c = this.cell(pos.x, pos.y);
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const i = c.indexOf(entity);
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if (i !== -1) c.splice(i, 1);
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},
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// bounds check
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inBounds(pos) {
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return (
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pos.x >= 0 && pos.x < this.width &&
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pos.y >= 0 && pos.y < this.height
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);
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},
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// call fn(entity, coord) for every entity in every cell
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each(fn) {
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for (let y = 0; y < this.height; y++) {
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for (let x = 0; x < this.width; x++) {
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const list = this.cells[y][x];
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for (let entity of list) {
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fn(entity, entity.coord);
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}
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}
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}
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},
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// printable representation
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toString() {
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let out = `grid [${this.width}×${this.height}]\n`;
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for (let y = 0; y < this.height; y++) {
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for (let x = 0; x < this.width; x++) {
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out += this.cells[y][x].length;
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}
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if (y !== this.height - 1) out += "\n";
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}
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return out;
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}
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};
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