Desert Generator

Terrain raycaster (optimised)
* by Mr.doob (http://mrdoob.com)
*
* Click for a new terrain

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license : All rights reserved
modified : 2009-01-06 07:41:30

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/*
 * Terrain raycaster (optimised)
 * by Mr.doob (http://mrdoob.com)
 *
 * Click for a new terrain
 */

package  
{
	import flash.display.Bitmap;
	import flash.display.BitmapData;
	import flash.display.BlendMode;
	import flash.display.Sprite;
	import flash.display.StageScaleMode;
	import flash.events.Event;
	import flash.events.MouseEvent;
	import flash.geom.Rectangle;

[SWF(backgroundColor="#000000", frameRate="60")] 
	public class Main extends Sprite 
	{
		private var precision : int = 1;
		
		private var canvas : BitmapData;
		private var canvas_width : int = 465;
		private var canvas_height : int = 465;
		private var canvas_width_half : int = canvas_width / 2;
		private var canvas_height_half : int = canvas_height / 2;	
		
		private var terrain_size : int = 1024;	
		
		private var light : Point3D;
		
		private var diffuseColor : Color;
		private var ambientColor : Color;
		private var fogColor : Color;
		private var skyColor : Color;
		
		private var pixelRect : Rectangle;
		private var lineRect : Rectangle;
		
		private var xx : int = 0;
		
		private var terrainH : BitmapData;
		private var fractaliser : BitmapData;
		
		private var camera_height : Number;
		private var prev_t : Number = 0.1;
		
		public function Main()
		{
			addEventListener( Event.ADDED_TO_STAGE, onAddedToStage );
		}
		
		private function onAddedToStage( e : Event ) : void
		{
			stage.scaleMode = StageScaleMode.NO_SCALE;
			
			canvas = new BitmapData( canvas_width, canvas_height, false, 0 );
			var sprite : Sprite = new Sprite();
			sprite.buttonMode = true;
			sprite.addChild( new Bitmap( canvas ) );
			addChild( sprite );

pixelRect = new Rectangle();
			lineRect = new Rectangle(0, 0, 1, canvas_height);
			
			terrainH = new BitmapData(terrain_size, terrain_size, false, 0);
			fractaliser = new BitmapData(terrain_size, terrain_size, false, 0);
			
			diffuseColor = new Color( 0x6f2d17 );
			ambientColor = new Color( 0x070300 );
			fogColor = new Color( 0x51547d );
			skyColor = new Color( 0xbbcde3 );

init();
			
			stage.addEventListener(MouseEvent.CLICK, init);
			addEventListener(Event.ENTER_FRAME, render);
		}
		
		private function init( e : Event = null ) : void
		{
			xx = 0;
			precision = 16;
			
			generateTerrain();
			light = new Point3D( (Math.random() - 0.5) * 2, Math.random(), (Math.random() - 0.5) * 2 );			
			// Need to sort this out to avoid camera inside sand
			//camera_height = f(canvas_width_half,canvas_width_half);
		}
		
		private function generateTerrain() : void
		{
			terrainH.perlinNoise(500, 500, 1, Math.random() * 100, true, false, 7, true);
			
			var i : int = 0;
			
			while(i++ < 3)
			{
				fractaliser.perlinNoise(500, 500, 1, Math.random() * 100, true, false, 7, true);
				terrainH.draw(fractaliser, null, null, BlendMode.DIFFERENCE);
			}
		}
		
		private function render( e : Event ) : void
		{
			canvas.lock();
			
			for (var yy : int = canvas_height; yy >= 0; yy -= precision)
			{
			 	var ray : Ray = new Ray();
				ray.origin = new Point3D( canvas_width_half, canvas_height_half, canvas_width_half);
				ray.direction = Point3D.sub( new Point3D(xx, canvas_height - yy, 0 ), ray.origin);
				ray.direction.normalise();

pixelRect.x = xx;
				pixelRect.y = yy;
				pixelRect.width = precision;
				pixelRect.height = precision;
				
				if (castRay(ray))
				{
					canvas.fillRect(pixelRect, terrainColor(ray) );
				}
				else
				{
					pixelRect.y = 0;
					pixelRect.height = yy + precision;
					canvas.fillRect(pixelRect, skyColor.getHex());
					break;
				}
				
				prev_t = 0.1;		
			}
			
			lineRect.x = xx + precision;
			canvas.fillRect(lineRect, 0xffffff );

if ((xx += precision) > canvas_width)
			{
				if (precision > 1)
					precision /= 2;
				else
					init();

xx = 0;
			}
			
			canvas.unlock();
		}	
		
		private function f( x : Number, z : Number) : Number
		{
			x = Math.abs((x - 250) * 1000) % terrain_size;
			z = Math.abs((z - 250) * 1000) % terrain_size;
			
			var f : Number = ((0x0000ff & terrainH.getPixel(x, z)) / 0xff) * .3;

return f - .1 + canvas_height_half;
		}
		
		private function castRay( ray : Ray ) : Boolean
		{
		    var delt : Number = 0.01;
		    var mint : Number = prev_t; //0.1;
		    var maxt : Number = 50.0;
		    
		    for( var t : Number = mint; t < maxt; t += delt )
		    {
		        var p : Point3D = Point3D.add(ray.origin, Point3D.scalar(ray.direction, t));
		        
		        if( p.y < f( p.x, p.z ) )
		        {
					prev_t = ray.t = t - 0.5 * delt;
		            return true;
		        }
		        
		        delt = 0.01 * t;   
		    }
		    return false;
		}
		
		private function terrainColor( ray : Ray ) : Number
		{	
			var p : Point3D = Point3D.add(ray.origin, Point3D.scalar(ray.direction, ray.t));
			var n : Point3D = getNormal(p);
			var dot : Number = Point3D.dot(n, light);
			
			var c : Color = new Color(0x000000);
						
			c.addRGB( diffuseColor );
			c.addNumber( dot * 0xFF );
			c.addRGB( ambientColor );
			c.mixRGB( fogColor, ray.t * 0.2);
						
			return c.getHex();
		}
		
		private function getNormal( p : Point3D ) : Point3D
		{
			var eps : Number = 0.01;
		    var normal : Point3D = new Point3D( f(p.x-eps,p.z) - f(p.x+eps,p.z),
		    									2 * eps, 
		    									f(p.x,p.z-eps) - f(p.x,p.z+eps) );
		    normal.normalise();
		    return normal;
		}		
	}
}

class Ray 
{
	public var origin : Point3D;
	public var direction : Point3D;
	public var t : Number;
}

class Point3D 
{
	public var x : Number;
	public var y : Number;
	public var z : Number;
	
	public function Point3D( x : Number = 0, y : Number = 0, z : Number = 0)
	{
		this.x = x;
		this.y = y;
		this.z = z; 
	}
	
	public function normalise() : void
	{
		var dist : Number = Math.sqrt( (x * x)+(y * y)+(z * z) );
		
		x = x * ( 1.0 / dist );
		y = y * ( 1.0 / dist );
		z = z * ( 1.0 / dist );
	}
	
	public static function add( p1 : Point3D, p2 : Point3D ) : Point3D
	{
		return new Point3D( p1.x + p2.x, p1.y + p2.y, p1.z + p2.z);
	}

public static function sub( p1 : Point3D, p2 : Point3D ) : Point3D
	{
		return new Point3D( p1.x - p2.x, p1.y - p2.y, p1.z - p2.z);
	}

public static function scalar( p1 : Point3D, val : Number ) : Point3D
	{
		return new Point3D( p1.x * val, p1.y * val, p1.z * val);
	}
		
	public static function dot( p1 : Point3D, p2 : Point3D ) : Number
	{
		return p1.x * p2.x + p1.y * p2.y + p1.z * p2.z;			
	}
		
	public function clone() : Point3D
	{
		return new Point3D(x, y , z);
	}
		
	public function toString() : String
	{
		return "x: " + x + ", y: " + y + ", z: " + z;
	}
}

class Color 
{
	public var r : int, g : int, b : int;
	
	public function Color( hex : int )
	{
		r = ( ( 0xff0000 & hex ) >> 16 );  
		g = ( ( 0xff00 & hex ) >> 8 );  
		b = ( ( 0xff & hex ) );
	}
		
	public function getHex() : int
	{
		r = ( r > 0xff ) ? 0xff : ( r < 0x00 ) ? 0 : r;
		g = ( g > 0xff ) ? 0xff : ( g < 0x00 ) ? 0 : g;
		b = ( b > 0xff ) ? 0xff : ( b < 0x00 ) ? 0 : b;	
			
		return r << 16 | g << 8 | b << 0;
	}

public function addNumber( value : int ) : void
	{
		r += value;
		g += value;
		b += value;
	}
		
	public function addRGB( colour : Color ) : void
	{
		r += colour.r;
		g += colour.g;
		b += colour.b;
	}
		
	public function mixRGB( colour : Color, amount : Number ) : void
	{
		amount = (amount > 1) ? 1 : (amount < 0) ? 0 : amount; 
			
		r = (r * (1 - amount)) + (colour.r * amount);
		g = (g * (1 - amount)) + (colour.g * amount);
		b = (b * (1 - amount)) + (colour.b * amount);
	}		
		
	public function multiplyNumber( value : Number ) : void
	{
		r *= value;
		g *= value;
		b *= value;
	}
}

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