1/*
2 * Copyright (C) 2009 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
17package com.android.gldual;
18
19import java.nio.ByteBuffer;
20import java.nio.ByteOrder;
21import java.nio.FloatBuffer;
22import java.nio.ShortBuffer;
23
24import javax.microedition.khronos.egl.EGLConfig;
25import javax.microedition.khronos.opengles.GL10;
26
27import android.opengl.GLSurfaceView;
28import android.opengl.GLU;
29import android.os.SystemClock;
30
31public class TriangleRenderer implements GLSurfaceView.Renderer{
32
33    public TriangleRenderer() {
34        mTriangle = new Triangle();
35    }
36
37    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
38        /*
39         * By default, OpenGL enables features that improve quality
40         * but reduce performance. One might want to tweak that
41         * especially on software renderer.
42         */
43        gl.glDisable(GL10.GL_DITHER);
44
45        /*
46         * Some one-time OpenGL initialization can be made here
47         * probably based on features of this particular context
48         */
49        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,
50                GL10.GL_FASTEST);
51
52        gl.glClearColor(.5f, .5f, .5f, 1);
53        gl.glShadeModel(GL10.GL_SMOOTH);
54    }
55
56    public void onDrawFrame(GL10 gl) {
57        /*
58         * By default, OpenGL enables features that improve quality
59         * but reduce performance. One might want to tweak that
60         * especially on software renderer.
61         */
62        gl.glDisable(GL10.GL_DITHER);
63
64        /*
65         * Usually, the first thing one might want to do is to clear
66         * the screen. The most efficient way of doing this is to use
67         * glClear().
68         */
69
70        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
71
72        /*
73         * Now we're ready to draw some 3D objects
74         */
75
76        gl.glMatrixMode(GL10.GL_MODELVIEW);
77        gl.glLoadIdentity();
78
79        GLU.gluLookAt(gl, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
80
81        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
82
83        long time = SystemClock.uptimeMillis() % 4000L;
84        float angle = 0.090f * ((int) time);
85
86        gl.glRotatef(angle, 0, 0, 1.0f);
87
88        mTriangle.draw(gl);
89    }
90
91    public void onSurfaceChanged(GL10 gl, int w, int h) {
92        gl.glViewport(0, 0, w, h);
93
94        /*
95        * Set our projection matrix. This doesn't have to be done
96        * each time we draw, but usually a new projection needs to
97        * be set when the viewport is resized.
98        */
99
100        float ratio = (float) w / h;
101        gl.glMatrixMode(GL10.GL_PROJECTION);
102        gl.glLoadIdentity();
103        gl.glFrustumf(-ratio, ratio, -1, 1, 3, 7);
104
105    }
106
107    private Triangle mTriangle;
108}
109
110class Triangle {
111    public Triangle() {
112
113        // Buffers to be passed to gl*Pointer() functions
114        // must be direct, i.e., they must be placed on the
115        // native heap where the garbage collector cannot
116        // move them.
117        //
118        // Buffers with multi-byte datatypes (e.g., short, int, float)
119        // must have their byte order set to native order
120
121        ByteBuffer vbb = ByteBuffer.allocateDirect(VERTS * 3 * 4);
122        vbb.order(ByteOrder.nativeOrder());
123        mFVertexBuffer = vbb.asFloatBuffer();
124
125        ByteBuffer tbb = ByteBuffer.allocateDirect(VERTS * 2 * 4);
126        tbb.order(ByteOrder.nativeOrder());
127
128        ByteBuffer ibb = ByteBuffer.allocateDirect(VERTS * 2);
129        ibb.order(ByteOrder.nativeOrder());
130        mIndexBuffer = ibb.asShortBuffer();
131
132        // A unit-sided equalateral triangle centered on the origin.
133        float[] coords = {
134                // X, Y, Z
135                -0.5f, -0.25f, 0,
136                 0.5f, -0.25f, 0,
137                 0.0f,  0.559016994f, 0
138        };
139
140        for (int i = 0; i < VERTS; i++) {
141            for(int j = 0; j < 3; j++) {
142                mFVertexBuffer.put(coords[i*3+j] * 2.0f);
143            }
144        }
145
146        for(int i = 0; i < VERTS; i++) {
147            mIndexBuffer.put((short) i);
148        }
149
150        mFVertexBuffer.position(0);
151        mIndexBuffer.position(0);
152    }
153
154    public void draw(GL10 gl) {
155        gl.glFrontFace(GL10.GL_CCW);
156        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, mFVertexBuffer);
157        gl.glDrawElements(GL10.GL_TRIANGLE_STRIP, VERTS,
158                GL10.GL_UNSIGNED_SHORT, mIndexBuffer);
159    }
160
161    private final static int VERTS = 3;
162
163    private FloatBuffer mFVertexBuffer;
164    private ShortBuffer mIndexBuffer;
165}
166