Android OpenGL学习札记(一)

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:

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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:

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复制打印
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 {@Overridepublic void onSurfaceCreated(GL10 gl, EGLConfig config) {// TODO Auto-generated method stubgl.glClearColor(0.9f, 0.2f, 0.2f, 1.0f);gl.glClear(GL10.GL_COLOR_BUFFER_BIT);}@Overridepublic void onSurfaceChanged(GL10 gl, int width, int height) {gl.glViewport(0, 0, width, height);}@Overridepublic 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:

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