EGL定义
是OpenGL EL和本地窗口系统的接口，不同平台上EGL配置是不一样的，而OpenGL的调用方式是一致的，OpenGL跨平台就是依赖于EGL接口
EGL环境创建目的
当我们需要把同一个场景渲染到不同的Surface上是，此时系统GLSurfaceView就不能满足需求了，需要自己创建EGL环境来实现渲染操作。
OpenGL整体是一个状态机，通过改变状态就可以改变后续的渲染方式，而EGLcontext（EGL上下文）保持所有的状态，因此可以通过共享EGLContext来实现同一个场景渲染到不同Surface上
GLSurfaceView有一个EglHelper
实例：创建自己的EglHelper
可参考GLSurfaceView里面的EglHelper方法
第一步：创建EglHelper类
public class EglHelper {
private EGL10 mEgl;
private EGLDisplay mEglDisplay;
private EGLContext mEglContext;
private EGLSurface mEglSurface;
public void initEgl(Surface surface, EGLContext eglContext)
{
//1、
mEgl = (EGL10) EGLContext.getEGL();
//2、
mEglDisplay = mEgl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);
if (mEglDisplay == EGL10.EGL_NO_DISPLAY) {
throw new RuntimeException("eglGetDisplay failed");
}
//3、
int[] version = new int[2];
if(!mEgl.eglInitialize(mEglDisplay, version)) {
throw new RuntimeException("eglInitialize failed");
}
//4、
int [] attrbutes = new int[]{
EGL10.EGL_RED_SIZE, 8,
EGL10.EGL_GREEN_SIZE, 8,
EGL10.EGL_BLUE_SIZE, 8,
EGL10.EGL_ALPHA_SIZE, 8,
EGL10.EGL_DEPTH_SIZE, 8,
EGL10.EGL_STENCIL_SIZE, 8,
EGL10.EGL_RENDERABLE_TYPE, 4,
EGL10.EGL_NONE};
int[] num_config = new int[1];
if(!mEgl.eglChooseConfig(mEglDisplay, attrbutes, null, 1, num_config))
{
throw new IllegalArgumentException("eglChooseConfig failed");
}
int numConfigs = num_config[0];
if (numConfigs <= 0) {
throw new IllegalArgumentException(
"No configs match configSpec");
}
//5、
EGLConfig[] configs = new EGLConfig[numConfigs];
if (!mEgl.eglChooseConfig(mEglDisplay, attrbutes, configs, numConfigs,
num_config)) {
throw new IllegalArgumentException("eglChooseConfig#2 failed");
}
//6、
if(eglContext != null)
{
mEglContext = mEgl.eglCreateContext(mEglDisplay, configs[0], eglContext, null);
}
else
{
mEglContext = mEgl.eglCreateContext(mEglDisplay, configs[0], EGL10.EGL_NO_CONTEXT, null);
}
//7、
mEglSurface = mEgl.eglCreateWindowSurface(mEglDisplay, configs[0], surface, null);
//8、
if(!mEgl.eglMakeCurrent(mEglDisplay, mEglSurface, mEglSurface, mEglContext))
{
throw new RuntimeException("eglMakeCurrent fail");
}
}
public boolean swapBuffers()
{
if(mEgl != null)
{
return mEgl.eglSwapBuffers(mEglDisplay, mEglSurface);
}
else
{
throw new RuntimeException("egl is null");
}
}
public EGLContext getmEglContext() {
return mEglContext;
}
public void destoryEgl()
{
if(mEgl != null)
{
mEgl.eglMakeCurrent(mEglDisplay, EGL10.EGL_NO_SURFACE,
EGL10.EGL_NO_SURFACE,
EGL10.EGL_NO_CONTEXT);
mEgl.eglDestroySurface(mEglDisplay, mEglSurface);
mEglSurface = null;
mEgl.eglDestroyContext(mEglDisplay, mEglContext);
mEglContext = null;
mEgl.eglTerminate(mEglDisplay);
mEglDisplay = null;
mEgl = null;
}
}
}
修改MainActivity代码
surfaceView = findViewById(R.id.surfaceview);
surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder holder) {
}
@Override
public void surfaceChanged(final SurfaceHolder holder, int format, final int width, final int height) {
new Thread() {
@Override
public void run() {
super.run();
//初始化EGL
EglHelper eglHelper = new EglHelper();
eglHelper.initEgl(holder.getSurface(),null);
while(true){
//设置窗口大小
GLES20.glViewport(0,0,width,height);
//清除颜色缓冲区
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
//使用指定颜色清屏
GLES20.glClearColor(1.0f,1.0f,0.0f,1.0f);
//自动刷新
eglHelper.swapBuffers();
try {
Thread.sleep(16);
}catch (InterruptedException e){
e.printStackTrace();
}
}
}
}.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
});
修改layout
<SurfaceView
android:id="@+id/surfaceview"
android:layout_width="match_parent"
android:layout_height="match_parent"></SurfaceView>
原文：https://www.cnblogs.com/cxj1821/p/12037560.html