Android example source code file (MatrixStack.java)

This example Android source code file (MatrixStack.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, default_max_depth, graphics, illegalargumentexception, io, matrix_size, matrixstack, nio, opengl

The MatrixStack.java Android example source code

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * 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.example.android.apis.graphics.spritetext;

import android.opengl.Matrix;

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

/**
 * A matrix stack, similar to OpenGL ES's internal matrix stack.
 */
public class MatrixStack {
    public MatrixStack() {
        commonInit(DEFAULT_MAX_DEPTH);
    }

    public MatrixStack(int maxDepth) {
        commonInit(maxDepth);
    }

    private void commonInit(int maxDepth) {
        mMatrix = new float[maxDepth * MATRIX_SIZE];
        mTemp = new float[MATRIX_SIZE * 2];
        glLoadIdentity();
    }

    public void glFrustumf(float left, float right, float bottom, float top,
            float near, float far) {
        Matrix.frustumM(mMatrix, mTop, left, right, bottom, top, near, far);
    }

    public void glFrustumx(int left, int right, int bottom, int top, int near,
            int far) {
        glFrustumf(fixedToFloat(left),fixedToFloat(right),
                fixedToFloat(bottom), fixedToFloat(top),
                fixedToFloat(near), fixedToFloat(far));
    }

    public void glLoadIdentity() {
        Matrix.setIdentityM(mMatrix, mTop);
    }

    public void glLoadMatrixf(float[] m, int offset) {
        System.arraycopy(m, offset, mMatrix, mTop, MATRIX_SIZE);
    }

    public void glLoadMatrixf(FloatBuffer m) {
        m.get(mMatrix, mTop, MATRIX_SIZE);
    }

    public void glLoadMatrixx(int[] m, int offset) {
        for(int i = 0; i < MATRIX_SIZE; i++) {
            mMatrix[mTop + i] = fixedToFloat(m[offset + i]);
        }
    }

    public void glLoadMatrixx(IntBuffer m) {
        for(int i = 0; i < MATRIX_SIZE; i++) {
            mMatrix[mTop + i] = fixedToFloat(m.get());
        }
    }

    public void glMultMatrixf(float[] m, int offset) {
        System.arraycopy(mMatrix, mTop, mTemp, 0, MATRIX_SIZE);
        Matrix.multiplyMM(mMatrix, mTop, mTemp, 0, m, offset);
    }

    public void glMultMatrixf(FloatBuffer m) {
        m.get(mTemp, MATRIX_SIZE, MATRIX_SIZE);
        glMultMatrixf(mTemp, MATRIX_SIZE);
    }

    public void glMultMatrixx(int[] m, int offset) {
        for(int i = 0; i < MATRIX_SIZE; i++) {
            mTemp[MATRIX_SIZE + i] = fixedToFloat(m[offset + i]);
        }
        glMultMatrixf(mTemp, MATRIX_SIZE);
    }

    public void glMultMatrixx(IntBuffer m) {
        for(int i = 0; i < MATRIX_SIZE; i++) {
            mTemp[MATRIX_SIZE + i] = fixedToFloat(m.get());
        }
        glMultMatrixf(mTemp, MATRIX_SIZE);
    }

    public void glOrthof(float left, float right, float bottom, float top,
            float near, float far) {
        Matrix.orthoM(mMatrix, mTop, left, right, bottom, top, near, far);
    }

    public void glOrthox(int left, int right, int bottom, int top, int near,
            int far) {
        glOrthof(fixedToFloat(left), fixedToFloat(right),
                fixedToFloat(bottom), fixedToFloat(top),
                fixedToFloat(near), fixedToFloat(far));
    }

    public void glPopMatrix() {
        preflight_adjust(-1);
        adjust(-1);
    }

    public void glPushMatrix() {
        preflight_adjust(1);
        System.arraycopy(mMatrix, mTop, mMatrix, mTop + MATRIX_SIZE,
                MATRIX_SIZE);
        adjust(1);
    }

    public void glRotatef(float angle, float x, float y, float z) {
        Matrix.setRotateM(mTemp, 0, angle, x, y, z);
        System.arraycopy(mMatrix, mTop, mTemp, MATRIX_SIZE, MATRIX_SIZE);
        Matrix.multiplyMM(mMatrix, mTop, mTemp, MATRIX_SIZE, mTemp, 0);
    }

    public void glRotatex(int angle, int x, int y, int z) {
        glRotatef(angle, fixedToFloat(x), fixedToFloat(y), fixedToFloat(z));
    }

    public void glScalef(float x, float y, float z) {
        Matrix.scaleM(mMatrix, mTop, x, y, z);
    }

    public void glScalex(int x, int y, int z) {
        glScalef(fixedToFloat(x), fixedToFloat(y), fixedToFloat(z));
    }

    public void glTranslatef(float x, float y, float z) {
        Matrix.translateM(mMatrix, mTop, x, y, z);
    }

    public void glTranslatex(int x, int y, int z) {
        glTranslatef(fixedToFloat(x), fixedToFloat(y), fixedToFloat(z));
    }

    public void getMatrix(float[] dest, int offset) {
        System.arraycopy(mMatrix, mTop, dest, offset, MATRIX_SIZE);
    }

    private float fixedToFloat(int x) {
        return x * (1.0f / 65536.0f);
    }

    private void preflight_adjust(int dir) {
        int newTop = mTop + dir * MATRIX_SIZE;
        if (newTop < 0) {
            throw new IllegalArgumentException("stack underflow");
        }
        if (newTop + MATRIX_SIZE > mMatrix.length) {
            throw new IllegalArgumentException("stack overflow");
        }
    }

    private void adjust(int dir) {
        mTop += dir * MATRIX_SIZE;
    }

    private final static int DEFAULT_MAX_DEPTH = 32;
    private final static int MATRIX_SIZE = 16;
    private float[] mMatrix;
    private int mTop;
    private float[] mTemp;
}