最近工作要用到OpenGL的技術,現在開始學習一些OpenGL ES的基礎知識,並記錄。
所有參考:
Android入門(4)OpenGL ES編程環境搭建
http://blog.csdn.net/silangquan/article/details/7938332一步一步學android OpenGL ES2.0編程(1)http://blog.csdn.net/niu_gao/article/details/8533126
1、Android Mainfest如下:
重點:<uses-feature android:glEsVersion="0x00020000" android:required="true"/>指明使用OpenGL的版本
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.test.opengl01"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="17"
android:targetSdkVersion="17" />
<uses-feature android:glEsVersion="0x00020000" android:required="true"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.test.opengl.MainActivity"
android:label="@string/app_name"
android:screenOrientation="portrait">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
</manifest>
2、MainActivity裏,只要定義GLSurfaceView mGLView即可,繪圖用的控件package com.test.opengl;
import android.app.Activity;
import android.opengl.GLSurfaceView;
import android.os.Bundle;
public class MainActivity extends Activity {
private GLSurfaceView mGLView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mGLView = new MyCLSurfaceView(this);
setContentView(mGLView);
}
@Override
protected void onPause() {
super.onPause();
mGLView.onPause();
}
@Override
protected void onResume() {
super.onResume();
mGLView.onResume();
}
}
3、MyCLSurfaceView,繼承自GLSurfaceView,只要創建OpenGL 的上下文對象,設置繪圖對象,並在繪製數據改變時才重繪MyCLSurfaceView
package com.test.opengl;
import android.content.Context;
import android.opengl.GLSurfaceView;
public class MyCLSurfaceView extends GLSurfaceView {
public MyCLSurfaceView(Context context) {
super(context);
// 創建一個OpenGL ES 2.0 context
setEGLContextClientVersion(2);
//設置Renderer到GLSurfaceView
setRenderer(new MyGL20Renderer());
//只有在繪製數據改變時才繪製view
setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
}
}
4、MyGL20Renderer,Renderer,所有的繪圖步驟全部在這裏實現
package com.test.opengl;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
/*此類控制向GLSurfaceView的繪製工作。它有三個方法被Android系統調用來計算在
* GLSurfaceView上畫什麼以及如何畫。
* onSurfaceCreated()- 僅調用一次,用於設置view的OpenGLES環境。
*onDrawFrame()- 每次View被重繪時被調用。
*onSurfaceChanged()- 如果view的幾和形狀發生變化了就調用,例如當豎屏變爲橫屏時。
*/
public class MyGL20Renderer implements GLSurfaceView.Renderer{
@Override
public void onDrawFrame(GL10 gl) {
//重繪背景色
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
mTriangle.draw();
}
@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
// TODO Auto-generated method stub
GLES20.glViewport(0, 0, width, height);
}
Triangle mTriangle = null;
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
//設置背景的顏色
// GLES20.glClearColor(red, green, blue, alpha)
GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
// 初始化一個三角形
mTriangle = new Triangle();
}
public static int loadShader(int type, String shaderCode){
// 創建一個vertex shader類型(GLES20.GL_VERTEX_SHADER)
// 或fragment shader類型(GLES20.GL_FRAGMENT_SHADER)
int shader = GLES20.glCreateShader(type);
// 將源碼添加到shader並編譯之
GLES20.glShaderSource(shader, shaderCode);
GLES20.glCompileShader(shader);
return shader;
}
}
5、如果要繪製某種形狀。則要自定義類來實現,所有繪圖的詳細過程在自定義類中實現。
package com.test.opengl;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import android.opengl.GLES20;
public class Triangle {
private FloatBuffer vertexBuffer;
//數組中每個頂點的座標數
static final int COORDS_PER_VERTEX = 3;
private final int vertexCount = triangleCoords.length / COORDS_PER_VERTEX;
private final int vertexStride = COORDS_PER_VERTEX * 4; // bytes per vertex
static float triangleCoords[] = {//逆時針
0.0f, 0.6f, 0.0f,//top
-0.5f, -0.3f, 0.0f,
0.5f, -0.3f, 0.0f
};
float color[] = {0.6f,0.7f,0.2f,1.0f};
private final String vertexShaderCode =
"attribute vec4 vPosition;" +
"void main() {" +
" gl_Position = vPosition;" +
"}";
private final String fragmentShaderCode =
"precision mediump float;" +
"uniform vec4 vColor;" +
"void main() {" +
" gl_FragColor = vColor;" +
"}";
public Triangle(){
//爲存放形狀的座標,初始化頂點字節座標
ByteBuffer bb = ByteBuffer.allocateDirect(triangleCoords.length *4);
//設置設備的頂點字節序
bb.order(ByteOrder.nativeOrder());
//從ByteBuffer創建一個浮點緩衝
vertexBuffer = bb.asFloatBuffer();
//把所有座標加入FloatBuffer中
vertexBuffer.put(triangleCoords);
//設置buffer爲從第一個座標讀起
vertexBuffer.position(0);
int vertexShader = MyGL20Renderer.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
int fragmentShader = MyGL20Renderer.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);
mProgram = GLES20.glCreateProgram(); // 創建一個空的OpenGL ES Program
GLES20.glAttachShader(mProgram, vertexShader); // 將vertex shader添加到program
GLES20.glAttachShader(mProgram, fragmentShader); // 將fragment shader添加到program
GLES20.glLinkProgram(mProgram); // 創建可執行的 OpenGL ES program
}
private final int mProgram;
private int mPositionHandle;
private int mColorHandle;//?????
public void draw() {
// 將program加入OpenGL ES環境中
GLES20.glUseProgram(mProgram);
// 獲取指向vertex shader的成員vPosition的 handle
mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
// 啓用一個指向三角形的頂點數組的handle
GLES20.glEnableVertexAttribArray(mPositionHandle);
// 準備三角形的座標數據
GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX,
GLES20.GL_FLOAT, false,
vertexStride, vertexBuffer);//????
// 獲取指向fragment shader的成員vColor的handle
mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");
// 設置三角形的顏色
GLES20.glUniform4fv(mColorHandle, 1, color, 0);
// 畫三角形
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);//??????
// 禁用指向三角形的頂點數組
GLES20.glDisableVertexAttribArray(mPositionHandle);
}
}