Android学习日记（yzy）：opengl 绘制2d图形 基本框架

首先，要了解opengl 在android中只有三种绘制方式-点,线，和三角形。

点的描绘方式：GL_POINTS

线的描绘方式：
GL_LINES(每两个顶点作为独立的线)
GL_LINE_STRIF(从第0个顶点到最后一个顶点依次相连)

GL_LINE_LOOP(从第0个顶点到最后一个顶点依次相连，最后一个顶点连接初始顶点)

三角形的绘制方式：
GL_TRIANGLES（以每三个顶点来形成三角形）
GL_TRIANGLES_STRIP（n,n+1,n+2依次连接的顶点形成的所有三角形）
GL_TRIANGLES_FAN (以第0个顶点确定，其余两个顶点依次为n，n+1来绘制三角形)


在绘制图像时，首先建一个类定义创建的图形形状。


第一步骤： float verticesArray 确定顶点， short indicesArray （索引）确定顺序。

第二步骤： 创建类如：Square（）{}来缓冲数据；
ByteBuffer vbb = ByteBuffer.allocateDirect(verticesArray.length * 4)开辟新的累存块
vbb.order(ByteOrder.nativeOrder())
FloatBuffer vertexBuffer = vbb.asFloatBuffer();
vertexBuffer.put(vertices);放入索引坐标数据
vertexBuffer.position(0);起始位置设定

第三步骤： 创建方法来构造形状
draw（ GL10 gl ）-->
gl.glColor4f(1.0f,0.0f,0.0f,1.0f);设置颜色
   gl.glTranslatef(0.1f,0,-2.0f);创建的形状初始坐标
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);采用顶点坐标数组
gl.glVertexPointer（3//坐标数，GL10.GL_FIXED,0，vertexBuffer//顶点坐标缓冲 ）指定顶点坐标数据
gl.glDrawElement(绘制方式，indicesArray.length//索引数,GL10.GL_UNSIGNED_SHORT//,索引缓冲)绘制图像

public class Square {    private float vertices[] = {            -0.1f, 0.1f, 0.0f,            -0.1f, -0.1f, 0.0f,            0.1f, -0.1f, 0.0f,            0.1f, 0.1f, 0.0f,    };    private short[] indices = {0, 1, 2, 0, 2, 3};    private FloatBuffer vertexBuffer;    private ShortBuffer indexBuffer;    public Square() {        ByteBuffer v_byteBuffer = ByteBuffer.allocateDirect(vertices.length * 4);        v_byteBuffer.order(ByteOrder.nativeOrder());        vertexBuffer = v_byteBuffer.asFloatBuffer();        vertexBuffer.put(vertices);        vertexBuffer.position(0);        ByteBuffer i_byteBuffer = ByteBuffer.allocateDirect(indices.length * 2);        i_byteBuffer.order(ByteOrder.nativeOrder());        indexBuffer = i_byteBuffer.asShortBuffer();        indexBuffer.put(indices);        indexBuffer.position(0);    }    public void draw(GL10 gl) {        gl.glColor4f(0.8f,0.0f,0.0f,1.0f);//        gl.glLoadIdentity();        gl.glTranslatef(0.1f,0,-2.0f);//        gl.glFrontFace(GL10.GL_CCW);//        gl.glEnable(GL10.GL_CULL_FACE);//        gl.glCullFace(GL10.GL_BACK);        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);        gl.glVertexPointer(3, GL10.GL_FLOAT, 0,                vertexBuffer);        gl.glDrawElements(GL10.GL_TRIANGLES, indices.length,                GL10.GL_UNSIGNED_SHORT, indexBuffer);//        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);//        gl.glDisable(GL10.GL_CULL_FACE);

其次，再创建接口类(GLSurfaceView.Renderer)作为你要放入图像的画布。

重写方法：onSurefaceCreated,onDrawFrame和onSurfaceChanged

第一步骤：onSurefaceCreated(GL10 gl,EGLConfig config){
gl.glShadeModel(GL10.GL_SMOOTH);抗锯齿
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,GL10.GL_NICEST);Hind模式
gl.glClearColor(0.0f,0.8f,0.0f,0.5f);桌布颜色
gl.glClearDepthf(1.0f);深度清理缓存
}


第二步骤：onDrawFrame(GL10 gl){
将之前描绘的图形初始化
  gl.glClear(GL10.GL_COLOR_BUFFER_BIT| GL10.GL_DEPTH_BUFFER_BIT);清理缓存
  gl.glLoadIdentity()设置当前矩阵为单位矩阵
  gl.glPushMatrix();
           drawLine.draw(gl);绘制图像
          gl.glPopMatrix();

}

第三步骤：onSurfaceChanged（GL10 gl,int width,int height）{
gl.glViewport(0,0,width,height)设置视图
gl.glMatrixMode(GL10.GL_PROJECTION);设置为投影矩阵
gl.glLoadIdentity()设置当前矩阵为单位矩阵
GLU.gluPerspective(gl,45.0f,(float)width/(float)height,0.1f,100.0f);
              gl.glMatrixMode(GL10.GL_MODELVIEW);
               gl.glLoadIdentity();
}

public class MyRenderer implements GLSurfaceView.Renderer {    Drawcub drawcub;    public void onSurfaceCreated(GL10 gl, EGLConfig config){        gl.glShadeModel(GL10.GL_SMOOTH);//抗锯齿        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,GL10.GL_NICEST);//Hind模式        gl.glClearColor(0.0f,0.0f,0.2f,0.5f);//桌布颜色        gl.glClearDepthf(1.0f);//深度清理缓存    }    public void onDrawFrame(GL10 gl){        Square square = new Square();        DrawPoint drawPoint = new DrawPoint();        DrawLine drawLine = new DrawLine();        gl.glClear(GL10.GL_COLOR_BUFFER_BIT                        | GL10.GL_DEPTH_BUFFER_BIT);        // Replace the current matrix with the identity matrix        gl.glLoadIdentity();        gl.glPushMatrix();//        square.draw(gl);        drawcub.drawSelf(gl);        gl.glPopMatrix();    }    public void onSurfaceChanged(GL10 gl,int width,int height){        gl.glViewport(0,0,width,height);        gl.glMatrixMode(GL10.GL_PROJECTION);        gl.glLoadIdentity();        GLU.gluPerspective(gl,45.0f,(float)width/(float)height,0.1f,100.0f);        drawcub = new Drawcub(0,0,0,3,(float)width/(float)height);        gl.glMatrixMode(GL10.GL_MODELVIEW);        gl.glLoadIdentity();    }

最后setContentView将初始化的GLSrefaceView（），放入activity中。

public class SceneRenderer implements GLSurfaceView.Renderer {    Drawcub drawcub;    public void onSurfaceCreated(GL10 gl, EGLConfig config){        gl.glShadeModel(GL10.GL_SMOOTH);//抗锯齿        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,GL10.GL_NICEST);//Hind模式        gl.glClearColor(0.0f,0.0f,0.2f,0.5f);//桌布颜色        gl.glClearDepthf(1.0f);//深度清理缓存    }    public void onDrawFrame(GL10 gl){        Square square = new Square();        DrawPoint drawPoint = new DrawPoint();        DrawLine drawLine = new DrawLine();        gl.glClear(GL10.GL_COLOR_BUFFER_BIT                        | GL10.GL_DEPTH_BUFFER_BIT);        // Replace the current matrix with the identity matrix        gl.glLoadIdentity();        gl.glPushMatrix();//        square.draw(gl);        drawcub.drawSelf(gl);        gl.glPopMatrix();    }    public void onSurfaceChanged(GL10 gl,int width,int height){        gl.glViewport(0,0,width,height);        gl.glMatrixMode(GL10.GL_PROJECTION);        gl.glLoadIdentity();        GLU.gluPerspective(gl,45.0f,(float)width/(float)height,0.1f,100.0f);        drawcub = new Drawcub(0,0,0,3,(float)width/(float)height);        gl.glMatrixMode(GL10.GL_MODELVIEW);        gl.glLoadIdentity();    }

续写，写了一个好玩的东西。

MainActivity：

public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        this.requestWindowFeature(Window.FEATURE_NO_TITLE);        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);        GLSurfaceView view = new GLSurfaceView(this);        view.setRenderer(new MyRenderer());        setContentView(view);    }}

MyRenderer:

public class MyRenderer implements GLSurfaceView.Renderer {    float positionX =0;    float positionY =0;    float positionZ =0;    float length = 0.5f;    float distance = 5;    private float angle;    Cube cube = new Cube(positionX,positionY,positionZ,length);    SquareTest squareTest = new SquareTest();    boolean flag =true;    public void onSurfaceCreated(GL10 gl, EGLConfig config){        gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f);        gl.glShadeModel(GL10.GL_SMOOTH);    //add        gl.glClearDepthf(1.0f);// OpenGL docs.        // Enables depth testing.        gl.glEnable(GL10.GL_DEPTH_TEST);// OpenGL docs.        // The type of depth testing to do.        gl.glDepthFunc(GL10.GL_LEQUAL);// OpenGL docs.        // Really nice perspective calculations.        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, // OpenGL docs.                GL10.GL_NICEST);    }    public void onDrawFrame(GL10 gl){        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);        gl.glLoadIdentity();        gl.glTranslatef(positionX ,positionY, positionZ-distance);        gl.glPushMatrix();        gl.glRotatef(angle, 5, 5, 5);//        square.onDraw(gl);        cube.onDraw(gl);        gl.glPopMatrix();        gl.glPushMatrix();        DynamicPicture();    }    private void DynamicPicture(){        angle++;        if (flag == true){            distance = distance+ 0.02f;            if (distance>=12){                flag = false;            }        }else if (flag ==false){            distance = distance-0.02f;            if(distance<=6){                flag =true;            }        }    }        public void onSurfaceChanged(GL10 gl,int width, int height){        gl.glViewport(0,0,width,height);        gl.glMatrixMode(GL10.GL_PROJECTION);        gl.glLoadIdentity();        GLU.gluPerspective(gl,45.0f,(float)width/(float)height,0.1f,100.0f);        gl.glMatrixMode(GL10.GL_MODELVIEW);        gl.glLoadIdentity();    }}

Cube：

public class Cube {    FloatBuffer verticesBuffer;    ShortBuffer indexBuffer;    int verticesCount ;    int indexCount;    public Cube(float positionX,float positionY,float positionZ, float length){        float vertices[] = {                positionX-length,positionY-length,positionZ-length,                -(positionX-length),positionY-length,positionZ-length,                -(positionX-length),-(positionY-length),positionZ-length,                positionX-length,-(positionY-length),positionZ-length,                positionX-length,positionY-length,-(positionZ-length),                -(positionX-length),positionY-length,-(positionZ-length),                -(positionX-length),-(positionY-length),-(positionZ-length),                positionX-length,-(positionY-length),-(positionZ-length),        };        short index[]={                0,1,1,2,2,3,3,0,                4,5,5,6,6,7,7,4,                0,4,1,5,2,6,3,7        };        ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length*4);        vbb.order(ByteOrder.nativeOrder());        verticesBuffer = vbb.asFloatBuffer();        verticesBuffer.put(vertices);        verticesBuffer.position(0);//        ByteBuffer ibb = ByteBuffer.allocateDirect(index.length*2);        ibb.order(ByteOrder.nativeOrder());        indexBuffer = ibb.asShortBuffer();        indexBuffer.put(index);        indexBuffer.position(0);        verticesCount = vertices.length;        indexCount = index.length;    }    public void onDraw(GL10 gl){        gl.glColor4f(1.0f, 1.0f, 1.0f, 1.0f);        gl.glFrontFace(GL10.GL_CCW);        gl.glEnable(GL10.GL_CULL_FACE);        gl.glCullFace(GL10.GL_BACK);        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);        gl.glVertexPointer(3, GL10.GL_FLOAT, 0,verticesBuffer);//GL_FLOAT        gl.glDrawElements(GL10.GL_LINES, indexCount, GL10.GL_UNSIGNED_SHORT, indexBuffer);        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);        gl.glDisable(GL10.GL_CULL_FACE);    }}