/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * 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 com.badlogic.gdx.graphics.g3d.attributes;

import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.g3d.Attribute;
import com.badlogic.gdx.math.MathUtils;
import com.badlogic.gdx.utils.GdxRuntimeException;
import com.badlogic.gdx.utils.NumberUtils;

public class DepthTestAttribute extends Attribute {
	public final static String Alias = "depthStencil";
	public final static long Type = register(Alias);

	protected static long Mask = Type;

	public final static boolean is (final long mask) {
		return (mask & Mask) != 0;
	}

	/** The depth test function, or 0 to disable depth test (default: GL10.GL_LEQUAL) */
	public int depthFunc;
	/** Mapping of near clipping plane to window coordinates (default: 0) */
	public float depthRangeNear;
	/** Mapping of far clipping plane to window coordinates (default: 1) */
	public float depthRangeFar;
	/** Whether to write to the depth buffer (default: true) */
	public boolean depthMask;

	public DepthTestAttribute () {
		this(GL20.GL_LEQUAL);
	}

	public DepthTestAttribute (boolean depthMask) {
		this(GL20.GL_LEQUAL, depthMask);
	}

	public DepthTestAttribute (final int depthFunc) {
		this(depthFunc, true);
	}

	public DepthTestAttribute (int depthFunc, boolean depthMask) {
		this(depthFunc, 0, 1, depthMask);
	}

	public DepthTestAttribute (int depthFunc, float depthRangeNear, float depthRangeFar) {
		this(depthFunc, depthRangeNear, depthRangeFar, true);
	}

	public DepthTestAttribute (int depthFunc, float depthRangeNear, float depthRangeFar, boolean depthMask) {
		this(Type, depthFunc, depthRangeNear, depthRangeFar, depthMask);
	}

	public DepthTestAttribute (final long type, int depthFunc, float depthRangeNear, float depthRangeFar, boolean depthMask) {
		super(type);
		if (!is(type)) throw new GdxRuntimeException("Invalid type specified");
		this.depthFunc = depthFunc;
		this.depthRangeNear = depthRangeNear;
		this.depthRangeFar = depthRangeFar;
		this.depthMask = depthMask;
	}

	public DepthTestAttribute (final DepthTestAttribute rhs) {
		this(rhs.type, rhs.depthFunc, rhs.depthRangeNear, rhs.depthRangeFar, rhs.depthMask);
	}

	@Override
	public Attribute copy () {
		return new DepthTestAttribute(this);
	}

	@Override
	public int hashCode () {
		int result = super.hashCode();
		result = 971 * result + depthFunc;
		result = 971 * result + NumberUtils.floatToRawIntBits(depthRangeNear);
		result = 971 * result + NumberUtils.floatToRawIntBits(depthRangeFar);
		result = 971 * result + (depthMask ? 1 : 0);
		return result; 
	}
	
	@Override
	public int compareTo (Attribute o) {
		if (type != o.type) return (int)(type - o.type);
		DepthTestAttribute other = (DepthTestAttribute)o;
		if (depthFunc != other.depthFunc) return depthFunc - other.depthFunc;
		if (depthMask != other.depthMask) return depthMask ? -1 : 1;
		if (!MathUtils.isEqual(depthRangeNear, other.depthRangeNear))
			return depthRangeNear < other.depthRangeNear ? -1 : 1;
		if (!MathUtils.isEqual(depthRangeFar, other.depthRangeFar))
			return depthRangeFar < other.depthRangeFar ? -1 : 1;
		return 0;
	}
}