基于Android的OpenGL ES 2.0学习笔记（1）

搬运以前在csdn的博文
之前大概接触过OpenGL ES 1.0，最近买了本书打算学习一下2.0的相关知识。本来以为顶多是多了一些API而已，结果真正学起来才发现用法完全不一样。最大的不同还是多了shader这么一个概念，目前我也没法完全理解shader是什么，只能在学习的过程中慢慢理解。不过基本的东西还都没变，点，线，三角等等

首先要使用es2.0的话需要先在manifest文件里声明

以下为Activity的代码

@Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        // 隐藏标题栏  
        requestWindowFeature(Window.FEATURE_NO_TITLE);  
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);  
  
        mPoint = new CZPoint();  
        // 初始化GLSurfaceView  
        GLSurfaceView glSurfaceView = new GLSurfaceView(this);  
        glSurfaceView.setEGLContextClientVersion(2);  
        glSurfaceView.setRenderer(new CZRenderer(mPoint));  
        setContentView(glSurfaceView);  
    }  
  
    @Override  
    public boolean onTouchEvent(MotionEvent event) {  
        // 获取touch的事件  
        float x = event.getX();  
        float y = event.getY();  
        switch (event.getAction()) {  
            case MotionEvent.ACTION_DOWN:  
                mPoint.setPosition(x * 2 / CZRenderer.width - 1.0f, 1.0f - y * 2 / CZRenderer.height);  
                mPoint.setColor(0.0f, 1.0f, 0.0f, 1.0f);  
                break;  
            case MotionEvent.ACTION_UP:  
                mPoint.setPosition(x * 2 / CZRenderer.width - 1.0f, 1.0f - y * 2 / CZRenderer.height);  
                mPoint.setColor(0.0f, 0.0f, 1.0f, 1.0f);  
                break;  
        }  
        return super.onTouchEvent(event);  
    }  

为了以后的扩展性定义了一个接口：

public interface ICZgles {  
    void init(int program, int vertexShader, int fragmentShader);  
    String getVertexShader();  
    String getFragmentShader();  
    void draw();  
}  

以下为顶点相关的类，其中涉及到glsl语言，以后还得慢慢学

public class CZPoint implements ICZgles {  
    private static final String TAG = "CZPoint";  
  
    private static final String VERTEX_SHADER  
            = "attribute vec4 a_Position;"  
            + "void main() {"  
            + "    gl_Position = a_Position;"  
            + "    gl_PointSize = 50.0;"  
            + "}";  
    private static final String FRAGMENT_SHADER  
            = "precision mediump float;"  
            + "uniform vec4 u_FragmentColor;"  
            + "void main() {"  
            + "    gl_FragColor = u_FragmentColor;"  
            + "}";  
  
    private int mAPosition;  
    private int mUFragmentColor;  
    private float[] mPosition = {0.0f, 0.0f};  
    private float[] mColor = {1.0f, 0.0f, 0.0f, 1.0f};  
  
    CZPoint() {  
        Log.d(TAG, "chenzhen");  
    }  
  
    @Override  
    public void init(int program, int vertexShader, int fragmentShader) {  
        mAPosition = GLES20.glGetAttribLocation(program, "a_Position");  
        mUFragmentColor = GLES20.glGetUniformLocation(program, "u_FragmentColor");  
    }  
  
    @Override  
    public String getVertexShader() {  
        return VERTEX_SHADER;  
    }  
  
    @Override  
    public String getFragmentShader() {  
        return FRAGMENT_SHADER;  
    }  
  
    @Override  
    public void draw() {  
        GLES20.glVertexAttrib3f(mAPosition, mPosition[0], mPosition[1], 0.0f);  
        GLES20.glUniform4f(mUFragmentColor, mColor[0], mColor[1], mColor[2], mColor[3]);  
        GLES20.glDrawArrays(GLES20.GL_POINTS, 0, 1);  
    }  
  
    public void setPosition(float x, float y) {  
        mPosition[0] = x;  
        mPosition[1] = y;  
    }  
  
    public void setColor(float r, float g, float b, float a) {  
        mColor[0] = r;  
        mColor[1] = g;  
        mColor[2] = b;  
        mColor[3] = a;  
    }  
} 

最后是Renderer的代码：

public class CZRenderer implements GLSurfaceView.Renderer {  
    public static float width = 0;  
    public static float height = 0;  
  
    private int mProgram;  
    private String mVertexShaderSource;  
    private String mFragmentShaderSource;  
    private ICZgles iCZ;  
  
    public CZRenderer(ICZgles icZgles) {  
        iCZ = icZgles;  
        mVertexShaderSource = iCZ.getVertexShader();  
        mFragmentShaderSource = iCZ.getFragmentShader();  
    }  
  
    @Override  
    public void onSurfaceCreated(GL10 gl10, EGLConfig eglConfig) {  
        GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);  
        mProgram = GLES20.glCreateProgram();  
        int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, mVertexShaderSource);  
        int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, mFragmentShaderSource);  
        GLES20.glAttachShader(mProgram, vertexShader);  
        GLES20.glAttachShader(mProgram, fragmentShader);  
        GLES20.glLinkProgram(mProgram);  
        GLES20.glUseProgram(mProgram);  
        iCZ.init(mProgram, vertexShader, fragmentShader);  
    }  
  
    @Override  
    public void onSurfaceChanged(GL10 gl10, int i, int i1) {  
        GLES20.glViewport(0, 0, i, i1);  
        width = i;  
        height = i1;  
    }  
  
    @Override  
    public void onDrawFrame(GL10 gl10) {  
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);  
        iCZ.draw();  
    }  
  
    private int loadShader(int type, String source) {  
        int shader = GLES20.glCreateShader(type);  
        GLES20.glShaderSource(shader, source);  
        GLES20.glCompileShader(shader);  
        return shader;  
    }  
}

针对shader多了很多api，也需要慢慢理解