我的render哪里写错了吗？为什么三角形显示不出来

/*

 *

 * Triangle.java

 * 

 * Created by Wuwang on 2016/9/30

 */

package edu.wuwang.opengl.render;



import android.opengl.GLES20;

import android.view.View;



import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.nio.FloatBuffer;



import javax.microedition.khronos.egl.EGLConfig;

import javax.microedition.khronos.opengles.GL10;



/**

 * Description:

 */

public class Triangle extends Shape {



    private FloatBuffer vertexBuffer;

    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 int mProgram;



    static final int COORDS_PER_VERTEX = 3;

    static float triangleCoords[] = {

            1f, 0f, 0f,

            0f, 1f, 0f,

            -1f, 0f, 0f

    };



    private int mPositionHandle;

    private int mColorHandle;



    private float[] mViewMatrix=new float[16];



    //顶点个数

    private final int vertexCount = triangleCoords.length / COORDS_PER_VERTEX;

    //顶点之间的偏移量

    private final int  vertexStride = COORDS_PER_VERTEX * 4; // 每个顶点四个字节



    private int mMatrixHandler;



    //设置颜色，依次为红绿蓝和透明通道

    float color[] = { 1.0f, 1.0f, 1.0f, 1.0f };



    public Triangle(View mView) {

        super(mView);

        ByteBuffer bb = ByteBuffer.allocateDirect(

                triangleCoords.length * 4);

        bb.order(ByteOrder.nativeOrder());



        vertexBuffer = bb.asFloatBuffer();

        vertexBuffer.put(triangleCoords);

        vertexBuffer.position(0);

        int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER,

                vertexShaderCode);

        int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);



        //创建一个空的OpenGLES程序

        mProgram = GLES20.glCreateProgram();

        //将顶点着色器加入到程序

        GLES20.glAttachShader(mProgram, vertexShader);

        //将片元着色器加入到程序中

        GLES20.glAttachShader(mProgram, fragmentShader);

        //连接到着色器程序

        GLES20.glLinkProgram(mProgram);

    }



    @Override

    public void onSurfaceCreated(GL10 gl, EGLConfig config) {



    }



    @Override

    public void onSurfaceChanged(GL10 gl, int width, int height) {



    }



    @Override

    public void onDrawFrame(GL10 gl) {



        //将程序加入到OpenGLES2.0环境

        GLES20.glUseProgram(mProgram);



        //获取顶点着色器的vPosition成员句柄

        mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");

        //启用三角形顶点的句柄

        GLES20.glEnableVertexAttribArray(mPositionHandle);

        //准备三角形的坐标数据

        GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX,

                GLES20.GL_FLOAT, false,

                vertexStride, vertexBuffer);

        //获取片元着色器的vColor成员的句柄

        mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");

        //设置绘制三角形的颜色

        GLES20.glUniform4fv(mColorHandle, 1, color, 0);

        //绘制三角形

        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);

        //禁止顶点数组的句柄

        GLES20.glDisableVertexAttribArray(mPositionHandle);

    }



}