OpenGL ES 纹理上画点,该如何解决

//绑定背景纹理，绘制背景纹理，代码略。。。。


//开始绘制红点
//gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
Dot myDot = new Dot();
myDot.draw(gl);

class Dot{
    private FloatBuffer vertexBuffer;
    //点的坐标（x, y, z)；
    private float vertices[] = {
            100.0f,100.0f,0,
            200.0f,200.0f,0,
            300.0f,300.0f,0,
            400.0f,400.0f,0
    };
    //准备顶点数据
    private void init(){
        ByteBuffer vertexByteBuffer = ByteBuffer.allocateDirect(vertices.length * 4);
        vertexByteBuffer.order(ByteOrder.nativeOrder());
        vertexBuffer = vertexByteBuffer.asFloatBuffer();
        vertexBuffer.put(vertices);
        
        vertexBuffer.position(0);
    }
    public Dot(){
        init();
    }
    public void draw(GL10 gl){
        //开始数组功能 GL_VERTEX_ARRAY
        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        //设定颜色值 此处为红  (red, green, blue, alpha)~[0.0f-1.0f]
        gl.glColor4f(1.0f, 0.0f, 0.0f, 1.0f);
        // 指向数组数据
        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
        //设置点的大小 为 5 像素
        gl.glPointSize(5);
        // 绘制点  GL_POINTS ； vertices.length/3 点的个数
        gl.glDrawArrays(GL10.GL_POINTS, 0, vertices.length / 3);
        //关闭数组功能 GL_VERTEX_ARRAY
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
    }
}