/*
 * Copyright 2012, Hannes Janetzek
 *
 * This program is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * This program 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.oscim.renderer.overlays;

import org.oscim.core.MapPosition;
import org.oscim.core.Tile;
import org.oscim.renderer.GLRenderer;
import org.oscim.renderer.GLRenderer.Matrices;
import org.oscim.view.MapView;

public abstract class RenderOverlay {

	protected final MapView mMapView;
	// keep the Position for which the Overlay is rendered
	protected MapPosition mMapPosition;

	// flag to set when data is ready for (re)compilation.
	public boolean newData;

	// flag set by GLRenderer when data is compiled
	public boolean isReady;

	public RenderOverlay(MapView mapView) {
		mMapView = mapView;
		mMapPosition = new MapPosition();
	}

	// /////////////// called from GLRender Thread ////////////////////////
	/**
	 * called 1. by GLRenderer. Set 'newData' true when 'compile()' should be
	 * called
	 * before next 'render()'
	 *
	 * @param curPos TODO
	 * @param positionChanged
	 *            true when MapPosition has changed
	 * @param tilesChanged
	 *            true when current tiles changed
	 * @param matrices TODO
	 */
	public abstract void update(MapPosition curPos, boolean positionChanged, boolean tilesChanged,
			Matrices matrices);

	/**
	 * called 2. compile everything for drawing
	 * Set 'isReady' true when things are ready for 'render()'
	 */
	public abstract void compile();

	/**
	 * called 3. draw overlay
	 *
	 * @param pos
	 *            current MapPosition
	 * @param m
	 *            current render matrices + matrix for temporary use
	 */
	public abstract void render(MapPosition pos, Matrices m);

	/**
	 * Utility: set m.mvp matrix relative to the difference of current
	 * MapPosition
	 * and the last updated Overlay MapPosition
	 *
	 * @param curPos
	 *            current MapPosition
	 * @param m
	 *            current Matrices
	 * @param project
	 *            apply view and projection, or just view otherwise
	 */
	protected void setMatrix(MapPosition curPos, Matrices m, boolean project) {
		MapPosition oPos = mMapPosition;

		double tileScale = Tile.TILE_SIZE * curPos.scale;

		double x = oPos.x - curPos.x;
		double y = oPos.y - curPos.y;

		// wrap around date-line
		while (x < 0)
			x += 1.0;
		while (x > 1)
			x -= 1.0;

		m.mvp.setTransScale((float) (x * tileScale), (float) (y * tileScale),
				(float) ((curPos.scale / oPos.scale) / GLRenderer.COORD_SCALE));

		m.mvp.multiplyMM(project ? m.viewproj : m.view, m.mvp);
	}

	/**
	 * Utility: set m.mvp matrix relative to the difference of current
	 * MapPosition
	 * and the last updated Overlay MapPosition and add m.viewproj
	 *
	 * @param curPos ...
	 * @param m ...
	 */
	protected void setMatrix(MapPosition curPos, Matrices m) {
		setMatrix(curPos, m, true);
	}
}