Android OpenGL学习笔记(一)

大家好，今天我讲一下Android OpenGL，这个系列是我的学习笔记，希望对大家有所帮助！这一节将给大家简洁的介绍一下术语，以及第一个Android OpenGL程序.

首先让我看们看一下术语:

Vertex (顶点)
A vertex is a point in 3D space and is the building block for many objects. In OpenGL you can specify as few as two coordinates (X,Y) and as many as four (X,Y,Z,W). The w-axis is optional, the default value is set to 1.0. The z-axis is also optional, the default value is set to 0. In this series, we will use the three main coordinates X, Y, and Z, since the W is generally used as a placeholder. The plural of vertex is vertices (mainly important for non native speakers, because it may create confusion). All objects are drawn using vertices as their points, so a point will refer to a vertex.

Triangle (三角)
A triangle requires three points to be created. So in OpenGL, we use three vertices to create one.

Polygon (多边形)
A polygon is an object which has at least three connected points. Therefor a triangle is also a polygon.

Primitives (基本实体)
A primitive is a three-dimensional object created using either triangles or polygons. A bit ironic: A detailed model with 50.000 vertices is also a primitive like a low detailed model with 500 vertices.

下面就是我们的第一个Android OpenGL程序:

 

 package    com.android.tutor;
 import    android.app.Activity;
 import    android.opengl.GLSurfaceView;
 import    android.os.Bundle;
 public     class    OpenGl_Lesson1  extends    Activity {
      public     void    onCreate(Bundle savedInstanceState) {
          super   .onCreate(savedInstanceState);

         GLSurfaceView mGlSurfaceView =  new    GLSurfaceView( this   );


         mGlSurfaceView.setRenderer( new    OpenGLRender());
         setContentView(mGlSurfaceView);

     }
 }

 package  com.android.tutor;
 import  android.app.Activity;
 import  android.opengl.GLSurfaceView;
 import  android.os.Bundle;
 public   class  OpenGl_Lesson1  extends  Activity {
     public   void  onCreate(Bundle savedInstanceState) {
         super .onCreate(savedInstanceState);

         GLSurfaceView mGlSurfaceView = new  GLSurfaceView( this );


         mGlSurfaceView.setRenderer(new  OpenGLRender());
         setContentView(mGlSurfaceView);

     }
 }

package com.android.tutor; import android.app.Activity; import android.opengl.GLSurfaceView; import android.os.Bundle; public class OpenGl_Lesson1 extends Activity { public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); GLSurfaceView mGlSurfaceView = new GLSurfaceView(this); mGlSurfaceView.setRenderer(new OpenGLRender()); setContentView(mGlSurfaceView); } }

我们这里的View是用的GLSurfaceView,但是它要setRenderer()一下，就像我们Activity里面的setContentView()方法一样!

这里的OpenGLRender是我重新写的类，它继承于GLSurfaceView.Renderer,我们要实现其种的三个方法:

onSurfaceCreated(),onSurfaceChanged(),onDrawFrame()。代码如下:

 

 package    com.android.tutor;
 import    javax.microedition.khronos.egl.EGLConfig;
 import    javax.microedition.khronos.opengles.GL10;
 import    android.opengl.GLSurfaceView.Renderer;
 public     class    OpenGLRender  implements    Renderer {
      @Override
      public     void    onSurfaceCreated(GL10 gl, EGLConfig config) {
          // TODO Auto-generated method stub

         gl.glClearColor( 0  .9f,  0  .2f,  0  .2f,  1  .0f);
         gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
     }
      @Override
      public     void    onSurfaceChanged(GL10 gl,  int    width,  int    height) {
         gl.glViewport( 0  ,  0  , width, height);
     }
      @Override
      public     void    onDrawFrame(GL10 gl) {
          // TODO Auto-generated method stub
     }

 }

 package  com.android.tutor;
 import  javax.microedition.khronos.egl.EGLConfig;
 import  javax.microedition.khronos.opengles.GL10;
 import  android.opengl.GLSurfaceView.Renderer;
 public   class  OpenGLRender  implements  Renderer {
     @Override
     public   void  onSurfaceCreated(GL10 gl, EGLConfig config) {
         // TODO Auto-generated method stub

         gl.glClearColor(0 .9f,  0 .2f,  0 .2f,  1 .0f);
         gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
     }
     @Override
     public   void  onSurfaceChanged(GL10 gl,  int  width,  int  height) {
         gl.glViewport(0 ,  0 , width, height);
     }
     @Override
     public   void  onDrawFrame(GL10 gl) {
         // TODO Auto-generated method stub
     }

 }

package com.android.tutor; import javax.microedition.khronos.egl.EGLConfig; import javax.microedition.khronos.opengles.GL10; import android.opengl.GLSurfaceView.Renderer; public class OpenGLRender implements Renderer { @Override public void onSurfaceCreated(GL10 gl, EGLConfig config) { // TODO Auto-generated method stub gl.glClearColor(0.9f, 0.2f, 0.2f, 1.0f); gl.glClear(GL10.GL_COLOR_BUFFER_BIT); } @Override public void onSurfaceChanged(GL10 gl, int width, int height) { gl.glViewport(0, 0, width, height); } @Override public void onDrawFrame(GL10 gl) { // TODO Auto-generated method stub } }

 第10行就是相当于我们设置画布颜色RGBA(红绿蓝透)，第11行这里是清除深度颜色缓存，不加上一句，第10句不起作用，整个View的颜色

还是黑黑的！

运行效果如下: