package org.codemonkey.papervision3d {
	import flash.utils.Dictionary;
	import org.papervision3d.cameras.Camera3D;
	import org.papervision3d.core.math.Number3D;
	import org.papervision3d.materials.special.ParticleMaterial;
	import org.papervision3d.objects.special.ParticleField;
	import org.papervision3d.scenes.Scene3D;
	
	/**
	 * Spacedust simulator. Creates 8 segments of the dustcloud around the given camera at any point in space.
	 * When the camera moves, new dustpockets are generated and old ones (out of sight) are removed.
	 *
	 * @author Benny Bottema
	 */
	public class Spacedust {
		
		private static const DEFAULT_PARTICLEMATERIAL:ParticleMaterial = new ParticleMaterial(0xffffff, .5, ParticleMaterial.SHAPE_CIRCLE);
		
		private var basic3DSetup:Basic3DSetup;
		private var camera:Camera3D;
		private var spacedustCloud:Dictionary;
		
		private var fieldsize:Number;
		private var particleCount:Number;
		private var dustMaterial:ParticleMaterial = new ParticleMaterial(0xffffff, .5, ParticleMaterial.SHAPE_CIRCLE);
		
		public function Spacedust(basic3DSetup:Basic3DSetup, camera:Camera3D = null, fieldsize:Number = 2500, particleCount:Number = 400, dustMaterial:ParticleMaterial = null) {
			spacedustCloud = new Dictionary();
			this.basic3DSetup = basic3DSetup;
			this.camera = (camera != null) ? camera : basic3DSetup.camera;
			this.fieldsize = fieldsize;
			this.particleCount = particleCount;
			this.dustMaterial = (dustMaterial != null) ? dustMaterial : DEFAULT_PARTICLEMATERIAL;
		}
		
		public function update():void {
			// calculate segment (dustpocket) size
			const FIELDSIZE_POCKET:Number = fieldsize / 5;
			
			// determine the 8 gridpositions around the ship (eg. 1: front bottom left, 2: behind top right)
			const pocketPositions:Array = new Array();
			pocketPositions.push(calcGridPosition(camera.position, FIELDSIZE_POCKET, false, false, false));
			pocketPositions.push(calcGridPosition(camera.position, FIELDSIZE_POCKET, true, false, false));
			pocketPositions.push(calcGridPosition(camera.position, FIELDSIZE_POCKET, false, true, false));
			pocketPositions.push(calcGridPosition(camera.position, FIELDSIZE_POCKET, false, false, true));
			pocketPositions.push(calcGridPosition(camera.position, FIELDSIZE_POCKET, true, true, false));
			pocketPositions.push(calcGridPosition(camera.position, FIELDSIZE_POCKET, true, false, true));
			pocketPositions.push(calcGridPosition(camera.position, FIELDSIZE_POCKET, false, true, true));
			pocketPositions.push(calcGridPosition(camera.position, FIELDSIZE_POCKET, true, true, true));
			
			const newSpacedustCloud:Dictionary = new Dictionary();
			
			// create new dustfields or transfer existing ones (and remove existing ones the scene)
			const particlesPerPocket:Number = particleCount / pocketPositions.length;
			for each (var pocketPosition:Number3D in pocketPositions) {
				const pocketKey:String = pocketPosition.toString();
				const reusableDustPocket:ParticleField = spacedustCloud[pocketKey];
				// remove so we can delete the particles from the remaining particlefields (which means they are out of sight)
				delete spacedustCloud[pocketKey];
				// add the removed particlefield to the new dustcloud or create one if dustpocket is new for te current gridposition around the ship
				if (reusableDustPocket != null) {
					basic3DSetup.scene.removeChild(reusableDustPocket);
					newSpacedustCloud[pocketKey] = reusableDustPocket;
				} else {
					newSpacedustCloud[pocketKey] = new ParticleField(dustMaterial, particlesPerPocket, 2, fieldsize, fieldsize, fieldsize);
					newSpacedustCloud[pocketKey].x = pocketPosition.x;
					newSpacedustCloud[pocketKey].y = pocketPosition.y;
					newSpacedustCloud[pocketKey].z = pocketPosition.z;
				}
			}
			
			// manually remove all the remaining obsolete particles from the old cloud (they are out of sight)
			for each (var oldDustPocket:ParticleField in spacedustCloud) {
				oldDustPocket.removeAllParticles();
			}
			
			// now add the old dustpockets which are still within sight, plus the new dustpockets to the scene
			for each (var newDustPocket:ParticleField in newSpacedustCloud) {
				basic3DSetup.scene.addChild(newDustPocket);
			}
			
			// replace the old cloud with the new cloud
			spacedustCloud = newSpacedustCloud;
		}
		
		/**
		 * Calculates a gridpoint around the ship.
		 */
		private function calcGridPosition(position:Number3D, gridSize:Number, xMin:Boolean, yMin:Boolean, zMin:Boolean):Number3D {
			const gridPosition:Number3D = new Number3D();
			gridPosition.x = (position.x - (position.x % gridSize)) + ((xMin) ? 0 : gridSize);
			gridPosition.y = (position.y - (position.y % gridSize)) + ((yMin) ? 0 : gridSize);
			gridPosition.z = (position.z - (position.z % gridSize)) + ((zMin) ? 0 : gridSize);
			return gridPosition;
		}
	}
}