57 lines
1.8 KiB
JavaScript
57 lines
1.8 KiB
JavaScript
// import {Texture} from '@pixi/core';
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// import {Sprite} from '@pixi/sprite';
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import {bresenham, createNoise2D, TAU} from '@/util/math.js';
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const simplex2D = createNoise2D();
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// TODO - 3d noise around a circumference of length polygon perimeter
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export function createLayerMask(layer) {
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const {area, hulls, tileSize} = layer;
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const canvas = window.document.createElement('canvas');
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if (0 === hulls.length) {
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return Texture.from(canvas);
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}
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[canvas.width, canvas.height] = [area.x * tileSize.x, area.y * tileSize.y];
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const ctx = canvas.getContext('2d');
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ctx.fillStyle = 'rgba(0, 0, 0, 1)';
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ctx.fillRect(0, 0, canvas.width, canvas.height);
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ctx.fillStyle = 'rgba(255, 255, 255, 1)';
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for (let i = 0; i < hulls.length; ++i) {
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const hull = [...hulls[i]];
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hull.push(hull[0]);
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ctx.beginPath();
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ctx.moveTo(hull[0].x, hull[0].y);
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for (let j = 0; j < hull.length - 1; j++) {
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const p0 = hull[j + 0];
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const p1 = hull[j + 1];
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const points = bresenham(p0, p1);
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const isReversed = (
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(p0.x > p1.x && points[0].x < points[points.length - 1].x)
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|| (p0.y > p1.y && points[0].y < points[points.length - 1].y)
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);
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for (
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let k = (isReversed ? points.length - 1 : 0);
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(isReversed ? k >= 0 : k < points.length);
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k += (isReversed ? -1 : 1)
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) {
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const {x, y} = points[k];
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const ANGLE_SCALE = 1000;
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const WALK_SCALE = 10;
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const MAGNITUDE = ((tileSize.x + tileSize.y) / 2) * simplex2D(x * 100, y * 100);
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const w = simplex2D(x * WALK_SCALE, y * WALK_SCALE);
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const r = TAU * simplex2D(x * ANGLE_SCALE, y * ANGLE_SCALE)
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ctx.lineTo(
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x + Math.cos(r) * w * MAGNITUDE,
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y + -Math.sin(r) * w * MAGNITUDE,
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);
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}
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}
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ctx.closePath();
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ctx.fill();
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}
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return Texture.from(canvas);
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}
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