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);

    }
}

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
    }

}

 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:

 

屏幕出现一闪一闪的解决方案是：把gl.glClearColor(0.9f, 0.2f, 0.2f, 1.0f);gl.glClear(GL10.GL_COLOR_BUFFER_BIT);放到onDrawFrame函数里面就行了