FullscreenQuad.java

/*******************************************************************************
 * Copyright (c) 2013 Philip Collin.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Public License v3.0
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/gpl.html
 * 
 * Contributors:
 *     Philip Collin - initial API and implementation
 ******************************************************************************/
package com.lyeeedar.Roguelike3D.Graphics.Models;

import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Mesh;
import com.badlogic.gdx.graphics.Mesh.VertexDataType;
import com.badlogic.gdx.graphics.VertexAttribute;
import com.badlogic.gdx.graphics.VertexAttributes.Usage;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;

/**
 * Encapsulates a fullscreen quad, geometry is aligned to the screen
 * corners.
 */
public class FullscreenQuad {
	private Mesh quad;

	public FullscreenQuad() {
		quad = createFullscreenQuad();
	}

	public void dispose() {
		quad.dispose();
	}

	/** Renders the quad with the specified shader program. */
	public void render( ShaderProgram program ) {
		quad.render( program, GL20.GL_TRIANGLE_FAN, 0, 4 );
	}

	private Mesh createFullscreenQuad() {
		// vertex coord
		verts[X1] = -1;
		verts[Y1] = -1;

		verts[X2] = 1;
		verts[Y2] = -1;

		verts[X3] = 1;
		verts[Y3] = 1;

		verts[X4] = -1;
		verts[Y4] = 1;

		// tex coords
		verts[U1] = 0f;
		verts[V1] = 0f;

		verts[U2] = 1f;
		verts[V2] = 0f;

		verts[U3] = 1f;
		verts[V3] = 1f;

		verts[U4] = 0f;
		verts[V4] = 1f;

		Mesh tmpMesh = new Mesh( VertexDataType.VertexArray, true, 4, 0, new VertexAttribute( Usage.Position, 2, "a_position" ),
				new VertexAttribute( Usage.TextureCoordinates, 2, "a_texCoord0" ) );

		tmpMesh.setVertices( verts );
		return tmpMesh;
	}

	private static final int VERT_SIZE = 16;
	private static float[] verts = new float[ VERT_SIZE ];
	private static final int X1 = 0;
	private static final int Y1 = 1;
	private static final int U1 = 2;
	private static final int V1 = 3;
	private static final int X2 = 4;
	private static final int Y2 = 5;
	private static final int U2 = 6;
	private static final int V2 = 7;
	private static final int X3 = 8;
	private static final int Y3 = 9;
	private static final int U3 = 10;
	private static final int V3 = 11;
	private static final int X4 = 12;
	private static final int Y4 = 13;
	private static final int U4 = 14;
	private static final int V4 = 15;
}