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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.apis.graphics.spritetext;
     18 
     19 import java.nio.ByteBuffer;
     20 import java.nio.ByteOrder;
     21 import java.nio.CharBuffer;
     22 import java.nio.FloatBuffer;
     23 
     24 import javax.microedition.khronos.opengles.GL10;
     25 
     26 /**
     27  * A 2D rectangular mesh. Can be drawn textured or untextured.
     28  *
     29  */
     30 class Grid {
     31 
     32     public Grid(int w, int h) {
     33         if (w < 0 || w >= 65536) {
     34             throw new IllegalArgumentException("w");
     35         }
     36         if (h < 0 || h >= 65536) {
     37             throw new IllegalArgumentException("h");
     38         }
     39         if (w * h >= 65536) {
     40             throw new IllegalArgumentException("w * h >= 65536");
     41         }
     42 
     43         mW = w;
     44         mH = h;
     45         int size = w * h;
     46         final int FLOAT_SIZE = 4;
     47         final int CHAR_SIZE = 2;
     48         mVertexBuffer = ByteBuffer.allocateDirect(FLOAT_SIZE * size * 3)
     49             .order(ByteOrder.nativeOrder()).asFloatBuffer();
     50         mTexCoordBuffer = ByteBuffer.allocateDirect(FLOAT_SIZE * size * 2)
     51             .order(ByteOrder.nativeOrder()).asFloatBuffer();
     52 
     53         int quadW = mW - 1;
     54         int quadH = mH - 1;
     55         int quadCount = quadW * quadH;
     56         int indexCount = quadCount * 6;
     57         mIndexCount = indexCount;
     58         mIndexBuffer = ByteBuffer.allocateDirect(CHAR_SIZE * indexCount)
     59             .order(ByteOrder.nativeOrder()).asCharBuffer();
     60 
     61         /*
     62          * Initialize triangle list mesh.
     63          *
     64          *     [0]-----[  1] ...
     65          *      |    /   |
     66          *      |   /    |
     67          *      |  /     |
     68          *     [w]-----[w+1] ...
     69          *      |       |
     70          *
     71          */
     72 
     73         {
     74             int i = 0;
     75             for (int y = 0; y < quadH; y++) {
     76                 for (int x = 0; x < quadW; x++) {
     77                     char a = (char) (y * mW + x);
     78                     char b = (char) (y * mW + x + 1);
     79                     char c = (char) ((y + 1) * mW + x);
     80                     char d = (char) ((y + 1) * mW + x + 1);
     81 
     82                     mIndexBuffer.put(i++, a);
     83                     mIndexBuffer.put(i++, b);
     84                     mIndexBuffer.put(i++, c);
     85 
     86                     mIndexBuffer.put(i++, b);
     87                     mIndexBuffer.put(i++, c);
     88                     mIndexBuffer.put(i++, d);
     89                 }
     90             }
     91         }
     92 
     93     }
     94 
     95     void set(int i, int j, float x, float y, float z, float u, float v) {
     96         if (i < 0 || i >= mW) {
     97             throw new IllegalArgumentException("i");
     98         }
     99         if (j < 0 || j >= mH) {
    100             throw new IllegalArgumentException("j");
    101         }
    102 
    103         int index = mW * j + i;
    104 
    105         int posIndex = index * 3;
    106         mVertexBuffer.put(posIndex, x);
    107         mVertexBuffer.put(posIndex + 1, y);
    108         mVertexBuffer.put(posIndex + 2, z);
    109 
    110         int texIndex = index * 2;
    111         mTexCoordBuffer.put(texIndex, u);
    112         mTexCoordBuffer.put(texIndex + 1, v);
    113     }
    114 
    115     public void draw(GL10 gl, boolean useTexture) {
    116         gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
    117         gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mVertexBuffer);
    118 
    119         if (useTexture) {
    120             gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
    121             gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, mTexCoordBuffer);
    122             gl.glEnable(GL10.GL_TEXTURE_2D);
    123         } else {
    124             gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
    125             gl.glDisable(GL10.GL_TEXTURE_2D);
    126         }
    127 
    128         gl.glDrawElements(GL10.GL_TRIANGLES, mIndexCount,
    129                 GL10.GL_UNSIGNED_SHORT, mIndexBuffer);
    130         gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
    131     }
    132 
    133     private FloatBuffer mVertexBuffer;
    134     private FloatBuffer mTexCoordBuffer;
    135     private CharBuffer mIndexBuffer;
    136 
    137     private int mW;
    138     private int mH;
    139     private int mIndexCount;
    140 }
    141