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      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 
     17 package com.android.gldual;
     18 
     19 import java.nio.ByteBuffer;
     20 import java.nio.ByteOrder;
     21 import java.nio.FloatBuffer;
     22 import java.nio.ShortBuffer;
     23 
     24 import javax.microedition.khronos.egl.EGLConfig;
     25 import javax.microedition.khronos.opengles.GL10;
     26 
     27 import android.opengl.GLSurfaceView;
     28 import android.opengl.GLU;
     29 import android.os.SystemClock;
     30 
     31 public 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 
    110 class 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