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| Copyright (c) 2014, Hunter Loftis. |
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| All rights reserved. |
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| 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. |
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| |
| <html> |
| <head> |
| <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0"> |
| <title>Terrain Demo - PlayfulJS</title> |
| <script src="../resources/runner.js"></script> |
| </head> |
| <body> |
| <canvas id='display' style='background: #000'></canvas> |
| |
| <script> |
| Math.random = (function() { |
| var seed = 49734321; |
| return function() { |
| /* The Jenkins hash function: |
| <http://en.wikipedia.org/wiki/Jenkins_hash_function> |
| <http://burtleburtle.net/bob/hash/integer.html> |
| */ |
| seed = ((seed + 0x7ed55d16) + (seed << 12)) & 0xffffffff; |
| seed = ((seed ^ 0xc761c23c) ^ (seed >>> 19)) & 0xffffffff; |
| seed = ((seed + 0x165667b1) + (seed << 5)) & 0xffffffff; |
| seed = ((seed + 0xd3a2646c) ^ (seed << 9)) & 0xffffffff; |
| seed = ((seed + 0xfd7046c5) + (seed << 3)) & 0xffffffff; |
| seed = ((seed ^ 0xb55a4f09) ^ (seed >>> 16)) & 0xffffffff; |
| return (seed & 0xfffffff) / 0x10000000; |
| }; |
| })(); |
| |
| function Terrain(detail) { |
| this.size = Math.pow(2, detail) + 1; |
| this.max = this.size - 1; |
| this.map = new Float32Array(this.size * this.size); |
| } |
| |
| Terrain.prototype.get = function(x, y) { |
| if (x < 0 || x > this.max || y < 0 || y > this.max) |
| return -1; |
| return this.map[x + this.size * y]; |
| }; |
| |
| Terrain.prototype.set = function(x, y, val) { |
| this.map[x + this.size * y] = val; |
| }; |
| |
| Terrain.prototype.generate = function(roughness) { |
| var self = this; |
| |
| this.set(0, 0, self.max); |
| this.set(this.max, 0, self.max / 2); |
| this.set(this.max, this.max, 0); |
| this.set(0, this.max, self.max / 2); |
| |
| divide(this.max); |
| |
| function divide(size) { |
| var x, y, half = size / 2; |
| var scale = roughness * size; |
| if (half < 1) |
| return; |
| |
| for (y = half; y < self.max; y += size) { |
| for (x = half; x < self.max; x += size) { |
| square(x, y, half, Math.random() * scale * 2 - scale); |
| } |
| } |
| for (y = 0; y <= self.max; y += half) { |
| for (x = (y + half) % size; x <= self.max; x += size) { |
| diamond(x, y, half, Math.random() * scale * 2 - scale); |
| } |
| } |
| divide(size / 2); |
| } |
| |
| function average(values) { |
| var valid = values.filter(function(val) { return val !== -1; }); |
| var total = valid.reduce(function(sum, val) { return sum + val; }, 0); |
| return total / valid.length; |
| } |
| |
| function square(x, y, size, offset) { |
| var ave = average([ |
| self.get(x - size, y - size), // upper left |
| self.get(x + size, y - size), // upper right |
| self.get(x + size, y + size), // lower right |
| self.get(x - size, y + size) // lower left |
| ]); |
| self.set(x, y, ave + offset); |
| } |
| |
| function diamond(x, y, size, offset) { |
| var ave = average([ |
| self.get(x, y - size), // top |
| self.get(x + size, y), // right |
| self.get(x, y + size), // bottom |
| self.get(x - size, y) // left |
| ]); |
| self.set(x, y, ave + offset); |
| } |
| }; |
| |
| Terrain.prototype.draw = function(ctx, width, height) { |
| var self = this; |
| var waterVal = this.size * 0.3; |
| |
| for (var y = 0; y < this.size; y++) { |
| for (var x = 0; x < this.size; x++) { |
| var val = this.get(x, y); |
| var top = project(x, y, val); |
| var bottom = project(x + 1, y, 0); |
| var water = project(x, y, waterVal); |
| var style = brightness(x, y, this.get(x + 1, y) - val); |
| |
| rect(top, bottom, style); |
| rect(water, bottom, 'rgba(50, 150, 200, 0.15)'); |
| } |
| } |
| |
| function rect(a, b, style) { |
| if (b.y < a.y) |
| return; |
| ctx.fillStyle = style; |
| ctx.fillRect(a.x, a.y, b.x - a.x, b.y - a.y); |
| } |
| |
| function brightness(x, y, slope) { |
| if (y === self.max || x === self.max) |
| return '#000'; |
| var b = ~~(slope * 50) + 128; |
| return ['rgba(', b, ',', b, ',', b, ',1)'].join(''); |
| } |
| |
| function iso(x, y) { |
| return { |
| x: 0.5 * (self.size + x - y), |
| y: 0.5 * (x + y) |
| }; |
| } |
| |
| function project(flatX, flatY, flatZ) { |
| var point = iso(flatX, flatY); |
| var x0 = width * 0.5; |
| var y0 = height * 0.2; |
| var z = self.size * 0.5 - flatZ + point.y * 0.75; |
| var x = (point.x - self.size * 0.5) * 6; |
| var y = (self.size - point.y) * 0.005 + 1; |
| |
| return { |
| x: x0 + x / y, |
| y: y0 + z / y |
| }; |
| } |
| }; |
| |
| var display = document.getElementById('display'); |
| var ctx = display.getContext('2d'); |
| var width = display.width = 1024; |
| var height = display.height = 768; |
| |
| PerfTestRunner.measureTime({ |
| run: function() { |
| var terrain = new Terrain(9); |
| terrain.generate(0.5); |
| ctx.clearRect(0, 0, width, height); |
| terrain.draw(ctx, width, height); |
| } |
| }); |
| </script> |
| </body> |
| </html> |
