OpenGL ES 2.0中绘制三角形（三）

前面已经简单框架搭好了，现在进行封装下一边以后更好的学习

1.我们都知道OpenGLES 呈现方式是依靠GLSurfaceView 来绘制出来的的那我们就从GLSurfaceView入手

public class FGLView extends GLSurfaceView {

    private FGLRender renderer;

    /*构造方法*/
    public FGLView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    /*初始化*/
    private void init(){
        /*OpenGL的版本 当前是OpenGL2*/
        setEGLContextClientVersion(2);
        /*这行代码是最重要的 渲染主要是Render来负责的*/
        setRenderer(renderer=new FGLRender(this));
        /*渲染的模式*/
        /** setRenderMode(Model)
         *public static final int RENDERMODE_CONTINUOUSLY = 1; 自动渲染模式
         * public static final int RENDERMODE_WHEN_DIRTY = 0; 脏模式 需要渲染才进行渲染
         */
        setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
    }

    /*适用于多个页面切换*/
    public void setShape(Class clazz){
        try {
            renderer.setShape(clazz);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

2。第一步就相当于xml 布局文件写完了，那么现在开始写 GLSurfaceView.Renderer 里面有三个 方法

//每一帧都会去绘制
    @Override
    public void onDrawFrame(GL10 gl) {}
//页面有改变的时候 例如生命周期改变的时候
        @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {}
//开始创建
        @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {}

开始封装FGLRender

public class FGLRender extends Shape {
    private static final String TAG = "zhangxin";
    private Shape shape;
    private Class clazz = Triangle.class;

    /*构造方法*/
    public FGLRender(View mView) {
        super(mView);
    }

    public void setShape(Class shape) {
        this.clazz = shape;
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
      //清屏让屏幕显示的颜色
        GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
        Log.e(TAG, "输出信息-->: onSurfaceCreated"  );
        try {
            //不知道，抄的
            Constructor constructor = clazz.getDeclaredConstructor(View.class);
            constructor.setAccessible(true);
            shape = (Shape) constructor.newInstance(mView);
        } catch (Exception e) {
            e.printStackTrace();
            shape = new Triangle(mView);
        }
        shape.onSurfaceCreated(gl, config);
    }

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

        Log.e(TAG, "输出信息-->: onSurfaceChanged" );
        //获取屏幕的大小
        GLES20.glViewport(0, 0, width, height);

        shape.onSurfaceChanged(gl, width, height);
    }

    @Override
    public void onDrawFrame(GL10 gl) {
        Log.e(TAG, "输出信息-->: onDrawFrame" );
        //清楚深度和颜色
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
        shape.onDrawFrame(gl);
    }
}

加载顶点着色器和片元着色器

public abstract class Shape implements GLSurfaceView.Renderer {

    protected View mView;
    public Shape(View mView){
        this.mView = mView;
    }

    public int loadShader (int type ,String shaderCode){
        /*根据type创建顶点着色器或者片元着色器*/
        int shader = GLES20.glCreateShader(type);
        /*将资源加入着色器中编译*/
        GLES20.glShaderSource(shader,shaderCode);
        GLES20.glCompileShader(shader);
        return shader;

    }
}

现在开始绘制三角形 主要呈现的就在Model3D

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[] = {
            0.5f,  0.5f, 0.0f, // top
            -0.5f, -0.5f, 0.0f, // bottom left
            0.5f, -0.5f, 0.0f  // bottom right
    };

    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);
    }
}

Activity代码

public class Load3DActivity extends AppCompatActivity {
    private static final String TAG = "zhangxin";
    private FGLView fglView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.loadopengl);
        init();
    }

    private void init() {
        fglView = (FGLView) findViewById(R.id.fglView);
    }

    @Override
    protected void onResume() {
        super.onResume();
        fglView.onResume();
    }

    @Override
    protected void onPause() {
        super.onPause();
        fglView.onPause();
    }
}

xml文件