Android入门（四）OpenGL ES编程环境搭建

Android入门（4）OpenGL ES编程环境搭建

一、提要

       偶然在Android developers看到这篇教程，遍一步步做了下来，下面是一点记录。

二、在Android中绘制OpenGL es的方法

     为了在Android应用中使用OpenGL绘制图形，我们必须创建一个View容器。一个最直接的方法就是implement GLSurfaceView 和a GLSurfaceView.Renderer。前者就是容器，后者控制View中渲染的内容。

    还有两种方法是SurfaceView和TextureView，但有点小复杂。

    最终效果：

三、必要的声明

在manifest文件中添加下面的代码：

package com.example.opengles;import java.nio.ByteBuffer;import java.nio.ByteOrder;import java.nio.FloatBuffer;import javax.microedition.khronos.egl.EGLConfig;import javax.microedition.khronos.opengles.GL10;import android.opengl.GLES20;import android.opengl.GLSurfaceView;public class MyRender implements GLSurfaceView.Renderer {private Triangle mTriangle;@Overridepublic void onDrawFrame(GL10 gl) {// TODO Auto-generated method stub        // Draw background color        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);        // Draw triangle       mTriangle.draw();}@Overridepublic void onSurfaceChanged(GL10 gl, int width, int height) {// TODO Auto-generated method stub  // Adjust the viewport based on geometry changes,        // such as screen rotation        GLES20.glViewport(0, 0, width, height);}    public static int loadShader(int type, String shaderCode){        // create a vertex shader type (GLES20.GL_VERTEX_SHADER)        // or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)        int shader = GLES20.glCreateShader(type);        // add the source code to the shader and compile it        GLES20.glShaderSource(shader, shaderCode);        GLES20.glCompileShader(shader);        return shader;    }@Overridepublic void onSurfaceCreated(GL10 gl, EGLConfig config) {// TODO Auto-generated method stub    // Set the background frame color        GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);        mTriangle = new Triangle();}}class Triangle {    private final String vertexShaderCode =        "attribute vec4 vPosition;" +        "void main() {" +        "  gl_Position = vPosition;" +        "}";    private final String fragmentShaderCode =        "precision mediump float;" +        "uniform vec4 vColor;" +        "void main() {" +        "  gl_FragColor = vColor;" +        "}";    private final FloatBuffer vertexBuffer;    private final int mProgram;    private int mPositionHandle;    private int mColorHandle;    // number of coordinates per vertex in this array    static final int COORDS_PER_VERTEX = 3;    static float triangleCoords[] = { // in counterclockwise order:         0.0f,  0.622008459f, 0.0f,   // top        -0.5f, -0.311004243f, 0.0f,   // bottom left         0.5f, -0.311004243f, 0.0f    // bottom right    };    private final int vertexCount = triangleCoords.length / COORDS_PER_VERTEX;    private final int vertexStride = COORDS_PER_VERTEX * 4; // bytes per vertex    // Set color with red, green, blue and alpha (opacity) values    float color[] = { 0.63671875f, 0.76953125f, 0.22265625f, 1.0f };    public Triangle() {        // initialize vertex byte buffer for shape coordinates        ByteBuffer bb = ByteBuffer.allocateDirect(                // (number of coordinate values * 4 bytes per float)                triangleCoords.length * 4);        // use the device hardware's native byte order        bb.order(ByteOrder.nativeOrder());        // create a floating point buffer from the ByteBuffer        vertexBuffer = bb.asFloatBuffer();        // add the coordinates to the FloatBuffer        vertexBuffer.put(triangleCoords);        // set the buffer to read the first coordinate        vertexBuffer.position(0);        // prepare shaders and OpenGL program        int vertexShader = MyRender.loadShader(GLES20.GL_VERTEX_SHADER,                                                   vertexShaderCode);        int fragmentShader = MyRender.loadShader(GLES20.GL_FRAGMENT_SHADER,                                                     fragmentShaderCode);        mProgram = GLES20.glCreateProgram();             // create empty OpenGL Program        GLES20.glAttachShader(mProgram, vertexShader);   // add the vertex shader to program        GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program        GLES20.glLinkProgram(mProgram);                  // create OpenGL program executables    }    public void draw() {        // Add program to OpenGL environment        GLES20.glUseProgram(mProgram);        // get handle to vertex shader's vPosition member        mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");        // Enable a handle to the triangle vertices        GLES20.glEnableVertexAttribArray(mPositionHandle);        // Prepare the triangle coordinate data        GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX,                                     GLES20.GL_FLOAT, false,                                     vertexStride, vertexBuffer);        // get handle to fragment shader's vColor member        mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");        // Set color for drawing the triangle        GLES20.glUniform4fv(mColorHandle, 1, color, 0);        // Draw the triangle        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);        // Disable vertex array        GLES20.glDisableVertexAttribArray(mPositionHandle);    }}