Android Open Source - android_breakout Base Rect

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License

The source code is released under:

Apache License

Java Source Code

/*
 * Copyright 2012 Google Inc. All Rights Reserved.
 *//from w w w  . ja  va2  s.c  om
 * 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.faddensoft.breakout;

import android.opengl.Matrix;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

/**
 * Base class for our graphical objects.
 */
public class BaseRect {
    /*
     * We keep track of position and scale (size) here.  Rather than holding these in fields
     * and copying them to the model/view matrix as needed, we just use the matrix as storage.
     */

    /**
     * Model/view matrix for this object.  Updated by setPosition() and setScale().  This
     * should be merged with the projection matrix when it's time to draw the object.
     */
    protected float[] mModelView;

    /**
     * Simple square, specified as a triangle strip.  The square is centered on (0,0) and has
     * a size of 1x1.
     * <p>
     * Triangles are 0-1-2 and 2-1-3 (counter-clockwise winding).
     */
    private static final float COORDS[] = {
        -0.5f, -0.5f,   // 0 bottom left
         0.5f, -0.5f,   // 1 bottom right
        -0.5f,  0.5f,   // 2 top left
         0.5f,  0.5f,   // 3 top right
    };

    /**
     * Texture coordinates.  These are flipped upside-down to match pixel data that starts
     * at the top left (typical of many image formats).
     */
    private static final float TEX_COORDS[] = {
        0.0f,   1.0f,   // bottom left
        1.0f,   1.0f,   // bottom right
        0.0f,   0.0f,   // top left
        1.0f,   0.0f,   // top right
    };

    /**
     * Square, suitable for GL_LINE_LOOP.  (The standard COORDS will create an hourglass.)
     * This is expected to have the same number of vertices and coords per vertex as COORDS.
     */
    private static final float OUTLINE_COORDS[] = {
        -0.5f, -0.5f,   // bottom left
         0.5f, -0.5f,   // bottom right
         0.5f,  0.5f,   // top right
        -0.5f,  0.5f,   // top left
    };

    // Common arrays of vertices.
    private static FloatBuffer sVertexArray = BaseRect.createVertexArray(COORDS);
    private static FloatBuffer sTexArray = BaseRect.createVertexArray(TEX_COORDS);
    private static FloatBuffer sOutlineVertexArray = BaseRect.createVertexArray(OUTLINE_COORDS);


    public static final int COORDS_PER_VERTEX = 2;         // x,y
    public static final int TEX_COORDS_PER_VERTEX = 2;     // s,t
    public static final int VERTEX_STRIDE = COORDS_PER_VERTEX * 4; // 4 bytes per float
    public static final int TEX_VERTEX_STRIDE = TEX_COORDS_PER_VERTEX * 4;

    // vertex count should be the same for both COORDS and TEX_COORDS
    public static final int VERTEX_COUNT = COORDS.length / COORDS_PER_VERTEX;


    protected BaseRect() {
        // Init model/view matrix, which holds position and scale.
        mModelView = new float[16];
        Matrix.setIdentityM(mModelView, 0);
    }

    /**
     * Allocates a direct float buffer, and populates it with the vertex data.
     */
    private static FloatBuffer createVertexArray(float[] coords) {
        // Allocate a direct ByteBuffer, using 4 bytes per float, and copy coords into it.
        ByteBuffer bb = ByteBuffer.allocateDirect(coords.length * 4);
        bb.order(ByteOrder.nativeOrder());
        FloatBuffer fb = bb.asFloatBuffer();
        fb.put(coords);
        fb.position(0);
        return fb;
    }

    /**
     * Returns a FloatBuffer with the vertex data for a unit-size square.  The vertices are
     * arranged for use with a ccw triangle strip.
     */
    public static FloatBuffer getVertexArray() {
        return sVertexArray;
    }

    /**
     * Returns a FloatBuffer with the texture coordinate data for an image with (0,0) in the
     * top-left corner.
     */
    public static FloatBuffer getTexArray() {
        return sTexArray;
    }

    /**
     * Returns a FloatBuffer with vertex data suitable for an outline rect (which has to
     * specify the vertices in a different order).
     */
    public static FloatBuffer getOutlineVertexArray() {
        return sOutlineVertexArray;
    }


    /**
     * Returns the X position (arena / world coordinates).
     */
    public float getXPosition() {
        return mModelView[12];
    }

    /**
     * Returns the Y position (arena / world coordinates).
     */
    public float getYPosition() {
        return mModelView[13];
    }

    /**
     * Sets the position in the arena.
     */
    public void setPosition(float x, float y) {
        // column-major 4x4 matrix
        mModelView[12] = x;
        mModelView[13] = y;
    }

    /**
     * Sets the position in the arena (X-coord only).
     */
    public void setXPosition(float x) {
        // column-major 4x4 matrix
        mModelView[12] = x;
    }

    /**
     * Gets the scale value in the X dimension.
     */
    public float getXScale() {
        return mModelView[0];
    }

    /**
     * Gets the scale value in the Y dimension.
     */
    public float getYScale() {
        return mModelView[5];
    }

    /**
     * Sets the size of the rectangle.
     */
    public void setScale(float xs, float ys) {
        // column-major 4x4 matrix
        mModelView[0] = xs;
        mModelView[5] = ys;
    }

    @Override
    public String toString() {
        return "[BaseRect x=" + getXPosition() + " y=" + getYPosition()
                + " xs=" + getXScale() + " ys=" + getYScale() + "]";
    }
}

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