/**
	Company:		Shout3D LLC
	Project:		Shout3D 2.0 Sample Code
	Class:			FogEffect
	Date:			March 23, 2000
	Description:	A simple example of a PostRenderEffect that adds a fog to the scene.
	(C) Copyright Shout3D LLC. - 1997-2001 - All rights reserved
 */

package custom_nodes;
import shout3d.core.*;
import shout3d.*;
import java.awt.Graphics;

/**
 * FogEffect
 *
 * @author Paul Isaacs
 */

public class FogEffect extends PostRenderEffect {

	// fogColor is the color that the scene fades to.
	// Objects closer than fogNear will render fully as their own color
	// Objects between fogNear and fogFar will fade linearly from their own color to fogColor
	// Objects farther than fogFar will be rendered fully as fogFar
	final public FloatArrayField  fogColor	  = new FloatArrayField(this, "fogColor", Field.COLOR, new float[]{0,0,0});
	final public FloatField       fogNear     = new FloatField(		this, "fogNear", Field.ANY, 0);
	final public FloatField       fogFar      = new FloatField(		this, "fogFar", Field.ANY, 50);
	/**
	 * Constructs a default FogEffect node.
	 */
	public FogEffect() {}

    public void filter(Graphics offScreenGraphics, int surface_pixel_bits[], float z_buffer[], int deviceWidth, int deviceHeight) {
		if (surface_pixel_bits == null || z_buffer == null)
			return;

		// Get the fog color components into byte form.
		int fogR = (int)(fogColor.getValue()[0]*255) &0xff;
		int fogG = (int)(fogColor.getValue()[1]*255) &0xff;
		int fogB = (int)(fogColor.getValue()[2]*255) &0xff;
		// Put the fog color components into a single aggregate int, suitable
		// for plopping into the array of pixels.
		int fogColorInt = 0xff000000 + (fogR<<16) + (fogG<<8) + fogB;

		// Handy variables.
		float f_far  = fogFar.getValue();
		float f_near = fogNear.getValue();
		float farMinusNear = f_far - f_near;

		float zDist, normZDist;

		float objRatio;
		int   imgR, imgG, imgB;

		// Iterate over all the pixels.
        for (int i=0;i<surface_pixel_bits.length;i++){
			if (z_buffer[i] <= 0) {
				// Background pixels get the fog color.
				surface_pixel_bits[i] = fogColorInt;
			}
			else {
				// z_buffer contents are actually entered as 1/z.
				// Need to use reciprocal to get distance.
				zDist = 1 / z_buffer[i];

				// Get normZDist.  This is 0 if closer than fogNear, 1 if farther
				// than fogFar, and interpolates linearly between them.
				if (zDist >= f_far)
					normZDist = 1f;
				else if (zDist <= f_near)
					normZDist = 0f;
				else
					normZDist = (float)((zDist - f_near)/farMinusNear);

				// The pixel gets a contribution of normZDist times the fog color,
				// plus (1-normZDist) times the color in the image.
				objRatio = (float)(1.0 - normZDist);
				imgR = (surface_pixel_bits[i]>>16)&0xff;
				imgG = (surface_pixel_bits[i]>>8)&0xff;
				imgB =  surface_pixel_bits[i] &0xff;
				surface_pixel_bits[i] = 0xff000000 +
						  (((int)(objRatio * imgR + normZDist * fogR)&0xff)<<16) +
						  (((int)(objRatio * imgG + normZDist * fogG)&0xff)<<8) +
						   ((int)(objRatio * imgB + normZDist * fogB)&0xff);
			}
        }
    }
}