Android example source code file (Projector.java)

This example Android source code file (Projector.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, graphics, matrixgrabber, opengl, projector

The Projector.java Android example source code

/*
 * Copyright (C) 2007 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.android.opengles.spritetext;

import android.opengl.Matrix;

import javax.microedition.khronos.opengles.GL10;

/**
 * A utility that projects
 *
 */
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;
}