package org.jzy3d.io.matlab;

import java.nio.FloatBuffer;
import java.nio.IntBuffer;

import org.apache.log4j.Logger;
import org.jzy3d.io.IGLLoader;
import org.jzy3d.maths.BoundingBox3d;
import org.jzy3d.maths.Coord3d;
import org.jzy3d.maths.Normal;
import org.jzy3d.plot3d.primitives.vbo.drawable.DrawableVBO;

import com.jmatio.io.MatFileReader;
import com.jmatio.types.MLNumericArray;
import com.jogamp.opengl.GL;

/**
 * Load a Matlab (TM) .mat file, assuming it contains at least three arrays named
 * "X", "Y" and "Z". 
 * 
 * Will fill buffers used to setup a {@link DrawableVBO} which efficiently load
 * geometries in GPU memory once program starts.
 * 
 * @author Martin Pernollet
 */
public class MatlabVBOLoader implements IGLLoader{
    protected String filename;
    
    public MatlabVBOLoader(String filename) {
        this.filename = filename;
    }

    @Override
    @SuppressWarnings("unchecked")
    public void load(GL gl, DrawableVBO drawable) throws Exception {
        MatFileReader mfr = new MatFileReader(filename);
        MLNumericArray x = (MLNumericArray) mfr.getMLArray("X");
        MLNumericArray y = (MLNumericArray) mfr.getMLArray("Y");
        MLNumericArray z = (MLNumericArray) mfr.getMLArray("Z");

        int n = x.getN(); // number of triangles
        int components = 3; // x, y, z
        int geomsize = 3; // triangle
        
        // Allocate content
        FloatBuffer vertices = FloatBuffer.allocate(n * (components*2) * geomsize); // *2 normals
        IntBuffer indices = IntBuffer.allocate(n * geomsize);
        BoundingBox3d bounds = new BoundingBox3d();
        
        // Feed buffers
        int size = 0;
        for (int i = 0; i < n; i++) {
            Coord3d c1 = new Coord3d(x.getReal(C1, i), y.getReal(C1, i), z.getReal(C1, i));
            Coord3d c2 = new Coord3d(x.getReal(C2, i), y.getReal(C2, i), z.getReal(C2, i));
            Coord3d c3 = new Coord3d(x.getReal(C3, i), y.getReal(C3, i), z.getReal(C3, i));
            Coord3d no = Normal.compute(c1, c2, c3);
            
            indices.put(size++);
            vertices.put(c1.x);
            vertices.put(c1.y);
            vertices.put(c1.z);
            vertices.put(no.x);
            vertices.put(no.y);
            vertices.put(no.z);            
            bounds.add(c1);
            
            indices.put(size++);
            vertices.put(c2.x);
            vertices.put(c2.y);
            vertices.put(c2.z);
            vertices.put(no.x);
            vertices.put(no.y);
            vertices.put(no.z);
            bounds.add(c2);

            indices.put(size++);
            vertices.put(c3.x);
            vertices.put(c3.y);
            vertices.put(c3.z);
            vertices.put(no.x);
            vertices.put(no.y);
            vertices.put(no.z);            
            bounds.add(c3);
        }
        vertices.rewind();
        indices.rewind();
        
        // Store in GPU
        drawable.setData(gl, indices, vertices, bounds);
        
        Logger.getLogger(MatlabVBOLoader.class).info("done loading " + filename);
    }

    
    protected static int C1 = 0;
    protected static int C2 = 1;
    protected static int C3 = 2;
}