Projector.java

package com.fiteclub.android.view;

/*
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/*
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*/

import android.opengl.Matrix;

import javax.microedition.khronos.opengles.GL10;

/**
 * A utility that projects
 *
 */
public class Projector {
    public Projector() {
        mMVP = new float[16];
        mV = new float[4];
        mGrabber = new MatrixGrabber();
    }

    public void setCurrentView(int x, int y, int width, int height) {
        mX = x;
        mY = y;
        mViewWidth = width;
        mViewHeight = height;
    }

    public void project(float[] obj, int objOffset, float[] win, int winOffset) {
        if (!mMVPComputed) {
            Matrix.multiplyMM(mMVP, 0, mGrabber.mProjection, 0, mGrabber.mModelView, 0);
            mMVPComputed = true;
        }

        Matrix.multiplyMV(mV, 0, mMVP, 0, obj, objOffset);

        float rw = 1.0f / mV[3];

        win[winOffset] = mX + mViewWidth * (mV[0] * rw + 1.0f) * 0.5f;
        win[winOffset + 1] = mY + mViewHeight * (mV[1] * rw + 1.0f) * 0.5f;
        win[winOffset + 2] = (mV[2] * rw + 1.0f) * 0.5f;
    }

    /**
     * Get the current projection matrix. Has the side-effect of
     * setting current matrix mode to GL_PROJECTION
     * @param gl
     */
    public void getCurrentProjection(GL10 gl) {
        mGrabber.getCurrentProjection(gl);
        mMVPComputed = false;
    }

    /**
     * Get the current model view matrix. Has the side-effect of
     * setting current matrix mode to GL_MODELVIEW
     * @param gl
     */
    public void getCurrentModelView(GL10 gl) {
        mGrabber.getCurrentModelView(gl);
        mMVPComputed = false;
    }

    private MatrixGrabber mGrabber;
    private boolean mMVPComputed;
    private float[] mMVP;
    private float[] mV;
    private int mX;
    private int mY;
    private int mViewWidth;
    private int mViewHeight;
}