/* Copyright (c) 2014 Jesper Öqvist <jesper@llbit.se>
 *
 * This file is part of Chunky.
 *
 * Chunky is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Chunky is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with Chunky.  If not, see <http://www.gnu.org/licenses/>.
 */
package se.llbit.chunky.renderer.projection;

import java.util.Random;

import se.llbit.math.QuickMath;
import se.llbit.math.Vector3;

/**
 * Moves the ray origin forward (if displacement is positive) along the
 * direction vector.
 */
public class ForwardDisplacementProjector implements Projector {
  protected final Projector wrapped;
  protected final double displacementValue;
  protected final double displacementSign;

  public ForwardDisplacementProjector(Projector wrapped, double displacement) {
    this.wrapped = wrapped;
    this.displacementValue = QuickMath.abs(displacement);
    this.displacementSign = QuickMath.signum(displacement);
  }

  @Override public void apply(double x, double y, Random random, Vector3 o, Vector3 d) {
    wrapped.apply(x, y, random, o, d);

    d.normalize();
    d.scale(displacementValue);
    o.scaleAdd(displacementSign, d);
  }

  @Override public void apply(double x, double y, Vector3 o, Vector3 d) {
    wrapped.apply(x, y, o, d);

    d.normalize();
    d.scale(displacementValue);
    o.scaleAdd(displacementSign, d);
  }

  @Override public double getMinRecommendedFoV() {
    return wrapped.getMinRecommendedFoV();
  }

  @Override public double getMaxRecommendedFoV() {
    return wrapped.getMaxRecommendedFoV();
  }

  @Override public double getDefaultFoV() {
    return wrapped.getDefaultFoV();
  }
}