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 
Grid(int w, int h)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 
set(int i, int j, float x, float y, float z, float u, float v)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 
draw(GL10 gl, boolean useTexture)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