Face.java

/*
 * Copyright (c) 2015 NOVA, All rights reserved.
 * This library is free software, licensed under GNU Lesser General Public License version 3
 *
 * This file is part of NOVA.
 *
 * NOVA 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.
 *
 * NOVA 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 NOVA.  If not, see <http://www.gnu.org/licenses/>.
 */

package nova.core.render.model;

import nova.core.render.texture.Texture;
import org.apache.commons.math3.geometry.euclidean.threed.Vector3D;

import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;

/**
 * A face is defined as at least 3 vertices joined together. It is group of vertices that result in a surface.
 *
 * @author Calclavia
 */
public class Face implements Cloneable {
	/**
	 * The vertices that make up this face.
	 */
	public final List<Vertex> vertices = new ArrayList<>();

	/**
	 * The normal (or direction) this face is facing.
	 * Normals must be unit vectors.
	 */
	public Vector3D normal = Vector3D.ZERO;

	/**
	 * The texture that is to be rendered on this face.
	 */
	public Optional<Texture> texture = Optional.empty();

	/**
	 * The brightness value defines how bright the face should be rendered.
	 * The default value will let NOVA decide the brightness based on the world surroundings.
	 */
	public double brightness = -1;

	/**
	 * Binds a specific texture to this artist.
	 *
	 * @param texture Texture to bind
	 * @return This Artist
	 */
	public Face bindTexture(Texture texture) {
		this.texture = Optional.of(texture);
		return this;
	}

	public Face drawVertex(Vertex vert) {
		vertices.add(vert);
		return this;
	}

	public double getBrightness() {
		return brightness;
	}

	/**
	 * Gets the center of this face.
	 *
	 * @return Center
	 */
	public Vector3D getCenter() {
		if (vertices.size() >= 3) {
			return vertices
				.stream()
				.map(v -> v.vec)
				.reduce(Vector3D.ZERO, Vector3D::add)
				.scalarMultiply(1f / vertices.size());
		}

		return Vector3D.ZERO;
	}

	@Override
	protected Face clone() {
		Face face = new Face();
		face.vertices.addAll(vertices.stream().map(Vertex::clone).collect(Collectors.toList()));
		face.normal = normal;
		face.texture = texture;
		face.brightness = brightness;
		return face;
	}
}