GridSurface.java

/**
 * Copyright (c) 2003-2009, Xith3D Project Group all rights reserved.
 * 
 * Portions based on the Java3D interface, Copyright by Sun Microsystems.
 * Many thanks to the developers of Java3D and Sun Microsystems for their
 * innovation and design.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the 'Xith3D Project Group' nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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package org.xith3d.terrain;

import org.xith3d.scenegraph.Appearance;
import org.openmali.vecmath2.TexCoord2f;

/**
 * A GridShader is used to "prepare" a given rectangular region of a regular grid. This means an
 * implementation provides an Appearance instance and appropriate texture coordinates for the area.
 * 
 * To enable effective data storage for LOD rendering of large scale landscapes, the prepare()
 * method accepts a detail argument specifying the needed resolution of the generated Appearance
 * (respectively for textures).
 * 
 * The values of the detail argument have no strict meaning other than a value 
 * of 0 requests the most detailed resolution, the GridSampler implementation
 * has to offer. Higher numbers are for less detailed data resolutions. A detail-level
 * of 0 requests the lowest available resolution. Typically (depends on the overall setup)
 * a detail-level of 2 requests the highest available resolution.
 *
 * @author Mathias 'cylab' Henze
 * @since 1.0
 */
public interface GridSurface extends GridResource
{
    /**
     * Returns an Appearance instance for a prepared rectangular region of the grid.
     * 
     * @param handle the handle of the prepared grid tile to texture
     */
    Appearance getAppearance();

    /**
     * Will be called to return the amount of texture units needed. 
     * @return the number of texture units
     */
    public int getTextureUnits();
    
    /**
     * Maps the passed grid coordinates to texture coordinates.
     *  
     * @param handle the handle of the prepared grid tile to texture
     * @param s the "longitude" coordinate of the grid
     * @param t the "latitude" coordinate of the grid 
     * @param unit the texture unit for which the coordinates have to be calculated.
     * @return a texture coordinate
     */
    public TexCoord2f map( float s, float t, int unit );

    public void release();
}