/*

This file is part of Earth.



Earth 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.



Earth 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 Earth.  If not, see <http://www.gnu.org/licenses/>.

*/



package com.zeph.android.earth;



import java.nio.IntBuffer;



import com.badlogic.gdx.Gdx;

import com.badlogic.gdx.assets.AssetManager;

import com.badlogic.gdx.graphics.GL20;

import com.badlogic.gdx.graphics.Mesh;

import com.badlogic.gdx.graphics.PerspectiveCamera;

import com.badlogic.gdx.graphics.Pixmap;

import com.badlogic.gdx.graphics.Texture;

import com.badlogic.gdx.graphics.glutils.ShaderProgram;

import com.badlogic.gdx.math.Matrix4;

import com.badlogic.gdx.utils.BufferUtils;

import com.badlogic.gdx.utils.GdxRuntimeException;



public class SkyBox {

	private Mesh cube;

	// private Pixmap[] textures = new Pixmap[6];

	private String[] textures = new String[6];

	private ShaderProgram program;

	private int g_cubeTexture;

	private Matrix4 invView = new Matrix4();

	private Matrix4 mvp = new Matrix4();



	private AssetManager manager;



	private static final String fragmentShader = "data/SkyBox-fragO.glsl";

	private static final String vertexShader = "data/SkyBox-vertO.glsl";



	public SkyBox(AssetManager manager, String[] faces) {



		this.manager = manager;

		this.textures = faces;



		g_cubeTexture = Texture.createGLHandle();

		Gdx.gl20.glBindTexture(GL20.GL_TEXTURE_CUBE_MAP, g_cubeTexture);



		program = new ShaderProgram(Gdx.files.internal(vertexShader)

				.readString(), Gdx.files.internal(fragmentShader).readString());

		if (!program.isCompiled())

			throw new GdxRuntimeException("Couldn't compile skybox shader: "

					+ program.getLog());



		cube = Shapes.genSkyBox();



		reloadCubemap();

	}



	public void reloadCubemap() {

		g_cubeTexture = Texture.createGLHandle();

		Gdx.gl20.glBindTexture(GL20.GL_TEXTURE_CUBE_MAP, g_cubeTexture);



		Pixmap temp = manager.get(textures[0], Pixmap.class);

		Gdx.gl.glTexImage2D(GL20.GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0,

				temp.getGLInternalFormat(), temp.getWidth(), temp.getHeight(),

				0, temp.getGLFormat(), temp.getGLType(), temp.getPixels());

		temp = manager.get(textures[1], Pixmap.class);

		Gdx.gl.glTexImage2D(GL20.GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 0,

				temp.getGLInternalFormat(), temp.getWidth(), temp.getHeight(),

				0, temp.getGLFormat(), temp.getGLType(), temp.getPixels());

		temp = manager.get(textures[2], Pixmap.class);

		Gdx.gl.glTexImage2D(GL20.GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 0,

				temp.getGLInternalFormat(), temp.getWidth(), temp.getHeight(),

				0, temp.getGLFormat(), temp.getGLType(), temp.getPixels());

		temp = manager.get(textures[3], Pixmap.class);

		Gdx.gl.glTexImage2D(GL20.GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 0,

				temp.getGLInternalFormat(), temp.getWidth(), temp.getHeight(),

				0, temp.getGLFormat(), temp.getGLType(), temp.getPixels());

		temp = manager.get(textures[4], Pixmap.class);

		Gdx.gl.glTexImage2D(GL20.GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0,

				temp.getGLInternalFormat(), temp.getWidth(), temp.getHeight(),

				0, temp.getGLFormat(), temp.getGLType(), temp.getPixels());

		temp = manager.get(textures[5], Pixmap.class);

		Gdx.gl.glTexImage2D(GL20.GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0,

				temp.getGLInternalFormat(), temp.getWidth(), temp.getHeight(),

				0, temp.getGLFormat(), temp.getGLType(), temp.getPixels());



		Gdx.gl20.glBindTexture(GL20.GL_TEXTURE_CUBE_MAP, g_cubeTexture);



		Gdx.gl20.glTexParameterf(GL20.GL_TEXTURE_CUBE_MAP,

				GL20.GL_TEXTURE_MAG_FILTER, GL20.GL_LINEAR);

		Gdx.gl20.glTexParameterf(GL20.GL_TEXTURE_CUBE_MAP,

				GL20.GL_TEXTURE_MIN_FILTER, GL20.GL_NEAREST);

		Gdx.gl20.glTexParameteri(GL20.GL_TEXTURE_CUBE_MAP,

				GL20.GL_TEXTURE_WRAP_S, GL20.GL_CLAMP_TO_EDGE);

		Gdx.gl20.glTexParameteri(GL20.GL_TEXTURE_CUBE_MAP,

				GL20.GL_TEXTURE_WRAP_T, GL20.GL_CLAMP_TO_EDGE);

	}



	public void render(PerspectiveCamera camera) {

		invView.set(camera.view);



		// Remove translation

		invView.val[Matrix4.M03] = 0;

		invView.val[Matrix4.M13] = 0;

		invView.val[Matrix4.M23] = 0;



		invView.inv().tra();



		mvp.set(camera.projection);

		mvp.mul(invView);



		Gdx.gl.glEnable(GL20.GL_CULL_FACE);

		Gdx.gl.glCullFace(GL20.GL_FRONT);

		Gdx.gl.glFrontFace(GL20.GL_CCW);



		Gdx.gl20.glDisable(GL20.GL_BLEND);

		Gdx.gl20.glDisable(GL20.GL_DEPTH_TEST);

		Gdx.gl20.glDepthMask(false);



		Gdx.gl20.glActiveTexture(GL20.GL_TEXTURE0);

		Gdx.gl20.glBindTexture(GL20.GL_TEXTURE_CUBE_MAP, g_cubeTexture);



		program.begin();



		program.setUniformMatrix("u_mvpMatrix", mvp);

		program.setUniformi("s_cubemap", 0);



		cube.render(program, GL20.GL_TRIANGLE_STRIP);



		program.end();



		Gdx.gl.glEnable(GL20.GL_DEPTH_TEST);

		Gdx.gl.glDepthMask(true);

	}



	public void resume() {

		reloadCubemap();

	}



	public void dispose() {

		for (int i = 0; i < 6; i++) {

			if (manager.isLoaded(textures[i])) {

				manager.unload(textures[i]);

			}

		}

		cube.dispose();



		IntBuffer buffer = BufferUtils.newIntBuffer(1);

		buffer.put(0, g_cubeTexture);

		Gdx.gl.glDeleteTextures(1, buffer);

	}

}