/*
 * Copyright (C) 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package org.ros.android.view.visualization;

import org.ros.rosjava_geometry.Transform;

import java.nio.FloatBuffer;

import javax.microedition.khronos.opengles.GL10;

/**
 * An adapter for applying {@link Transform}s in an OpenGL context.
 * 
 * @author damonkohler@google.com (Damon Kohler)
 * @author moesenle@google.com (Lorenz Moesenlechner)
 */
public class OpenGlTransform {

  private static final ThreadLocal<FloatBuffer> buffer = new ThreadLocal<FloatBuffer>() {
    @Override
    protected FloatBuffer initialValue() {
      return FloatBuffer.allocate(16);
    };

    @Override
    public FloatBuffer get() {
      FloatBuffer buffer = super.get();
      buffer.clear();
      return buffer;
    };
  };

  private OpenGlTransform() {
    // Utility class.
  }

  /**
   * Applies a {@link Transform} to an OpenGL context.
   * 
   * @param gl
   *          the context
   * @param transform
   *          the {@link Transform} to apply
   */
  public static void apply(GL10 gl, Transform transform) {
    FloatBuffer matrix = buffer.get();
    for (double value : transform.toMatrix()) {
      matrix.put((float) value);
    }
    matrix.position(0);
    gl.glMultMatrixf(matrix);
  }
}
