101 lines
2.7 KiB
JavaScript
101 lines
2.7 KiB
JavaScript
import {createCanvas, drawRect, clipCanvas, drawCircle} from './gfx.js';
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import {coords2index, random, randomInt, clamp} from './math.js';
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import {sample} from './utils.js';
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let cachedImageData;
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function cacheImageData(ctx) {
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const {width, height} = ctx.canvas;
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cachedImageData = ctx.getImageData(0, 0, width, height);
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}
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export function createTerrain(width, height) {
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const terrain = createCanvas(width, height);
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const generateTerrain = sample(Object.values(TERRAIN_TYPES));
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generateTerrain(terrain);
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return terrain;
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}
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const TERRAIN_TYPES = {
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mountain(ctx) {
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ctx.color = sample(['palegreen', 'white']); // FIXME
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const {width, height} = ctx.canvas;
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const stepCount = 8;
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const stepSize = width / stepCount;
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let cy = random(.3, .7) * height;
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let dy = 0;
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for (let x=0; x<width; x++) {
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if (x % stepSize === 0) dy = ((random(.3, .7) * height) - cy) / stepSize;
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if (x % (stepSize/16) === 0) dy = dy - random(-1, 1);
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const ty = clamp(0, cy+dy, height-1);
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const wy = clamp(70, ty, height-70-1);
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cy = wy + (ty-wy) * 0.5;
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drawRect(ctx, x, cy, 1, height-cy, ctx.color);
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}
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cacheImageData(ctx);
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},
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sand(ctx) {
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ctx.color = 'wheat';
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const {width, height} = ctx.canvas;
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const stepCount = 16;
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const stepSize = width / stepCount;
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for (let s=0; s<=stepCount; s++) {
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drawCircle(ctx, s*stepSize, height, randomInt(stepSize, stepSize*2), ctx.color);
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if (s % 3 === 0) drawCircle(ctx, s*stepSize, 0, randomInt(0, stepSize*4), ctx.color);
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}
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cacheImageData(ctx);
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collapseTerrain(ctx);
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}
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};
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export function collapseTerrain(ctx, ) {
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const {width, height} = ctx.canvas;
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const imageData = ctx.getImageData(0, 0, width, height);
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for (let x=0; x<width; x++) {
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let land = 0;
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for (let y=0; y<height; y++) {
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const index = y*width*4 + x*4 +3;
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if (imageData.data[index] > 0) land++;
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}
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ctx.clearRect(0+x, 0, 1, height);
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drawRect(ctx, 0+x, height-land, 1, land, ctx.color);
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}
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cacheImageData(ctx);
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}
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export function isTerrain(ctx, x, y) {
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const index = coords2index(ctx.canvas.width, x, y) * 4;
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return cachedImageData.data[index+3] > 0;
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}
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export function closestLand(ctx, x, y) {
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const {width, height} = ctx.canvas;
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for (let i=y; i<height; i++) {
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const index = coords2index(width, x, i) * 4;
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if (cachedImageData.data[index+3] !== 0) return i;
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}
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return height-1;
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}
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export function landHeight(ctx, x) {
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const {width, height} = ctx.canvas;
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for (let i=height-1; i>=0; i--) {
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const index = coords2index(width, x, i) * 4;
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if (cachedImageData.data[index+3] === 0) return i;
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}
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}
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export function clipTerrain(ctx, fn) {
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clipCanvas(ctx, fn);
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cacheImageData(ctx);
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}
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