我想在本机代码上在
Android上进行屏幕外图像处理,因此我需要通过EGL在本机代码中创建openGL上下文.
通过EGL,我们可以创建EGLSurface,我可以看到有三种选择：
* EGL_WINDOW_BIT
* EGL_PIXMAP_BIT
* EGL_BUFFER_BIT
第一个用于屏幕处理,第二个用于屏幕外,因此我使用EGL_PIXMAP_BIT,如下所示：
// Step 1 - Get the default display.
EGLDisplay eglDisplay = eglGetDisplay((EGLNativeDisplayType) 0);
if ((eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY)) == EGL_NO_DISPLAY) {
LOGH("eglGetDisplay() returned error %d",eglGetError());
exit(-1);
}
// Step 2 - Initialize EGL.
if (!eglInitialize(eglDisplay,0)) {
LOGH("eglInitialize() returned error %d",eglGetError());
exit(-1);
}
// Step 3 - Make OpenGL ES the current API.
eglBindAPI(EGL_OPENGL_ES_API);
// Step 4 - Specify the required configuration attributes.
EGLint pi32ConfigAttribs[] = { EGL_SURFACE_TYPE,EGL_PIXMAP_BIT,EGL_BLUE_SIZE,8,EGL_GREEN_SIZE,EGL_RED_SIZE,EGL_NONE,EGL_BIND_TO_TEXTURE_RGBA,EGL_TRUE };
// Step 5 - Find a config that matches all requirements.
int iConfigs;
EGLConfig eglConfig;
eglChooseConfig(eglDisplay,pi32ConfigAttribs,&eglConfig,1,&iConfigs);
if (iConfigs != 1) {
LOGH(
"Error: eglChooseConfig(): config not found %d - %d.\n",eglGetError(),iConfigs);
exit(-1);
}
// Step 6 - Create a surface to draw to.
EGLSurface eglSurface = eglCreatePbufferSurface(eglDisplay,eglConfig,NULL);
// Step 7 - Create a context.
EGLContext eglContext = eglCreateContext(eglDisplay,NULL,ai32ContextAttribs);
// Step 8 - Bind the context to the current thread
eglMakeCurrent(eglDisplay,eglSurface,eglContext);
解决方法
您正在尝试使用仅在Android上无法运行的EGL选项,而pbuffers仅适用于某些GPU – 而不是Nvidia Tegra. pi32ConfigAttribs []看起来应该是这样的,无论它是在屏幕上还是在屏幕外：
EGLint pi32ConfigAttribs[] =
{
EGL_RENDERABLE_TYPE,EGL_OPENGL_ES2_BIT,EGL_ALPHA_SIZE,EGL_DEPTH_SIZE,EGL_STENCIL_SIZE,EGL_NONE
};
Android在支持屏幕外EGLSurfaces方面非常缺乏灵活性.他们定义了自己的名为EGL_NATIVE_BUFFER_ANDROID的pixmap类型.
要在Android上创建一个离屏的EGL表面,请构造一个SurfaceTexture并将其传递给eglCreateWindowSurface().您还应该查看使用EGL图像扩展和EGL_NATIVE_BUFFER_ANDROID,如下所述：
http://software.intel.com/en-us/articles/using-opengl-es-to-accelerate-apps-with-legacy-2d-guis
更新：
以下是一些创建屏幕外表面的示例代码：
private EGL10 mEgl;
private EGLConfig[] maEGLconfigs;
private EGLDisplay mEglDisplay = null;
private EGLContext mEglContext = null;
private EGLSurface mEglSurface = null;
private EGLSurface[] maEglSurfaces = new EGLSurface[MAX_SURFACES];
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture,int width,int height)
{
InitializeEGL();
CreateSurfaceEGL(surfaceTexture,width,height);
}
private void InitializeEGL()
{
mEgl = (EGL10)EGLContext.getEGL();
mEglDisplay = mEgl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);
if (mEglDisplay == EGL10.EGL_NO_DISPLAY)
throw new RuntimeException("Error: eglGetDisplay() Failed " + GLUtils.getEGLErrorString(mEgl.eglGetError()));
int[] version = new int[2];
if (!mEgl.eglInitialize(mEglDisplay,version))
throw new RuntimeException("Error: eglInitialize() Failed " + GLUtils.getEGLErrorString(mEgl.eglGetError()));
maEGLconfigs = new EGLConfig[1];
int[] configsCount = new int[1];
int[] configSpec = new int[]
{
EGL10.EGL_RENDERABLE_TYPE,EGL10.EGL_RED_SIZE,EGL10.EGL_GREEN_SIZE,EGL10.EGL_BLUE_SIZE,EGL10.EGL_ALPHA_SIZE,EGL10.EGL_DEPTH_SIZE,EGL10.EGL_STENCIL_SIZE,EGL10.EGL_NONE
};
if ((!mEgl.eglChooseConfig(mEglDisplay,configSpec,maEGLconfigs,configsCount)) || (configsCount[0] == 0))
throw new IllegalArgumentException("Error: eglChooseConfig() Failed " + GLUtils.getEGLErrorString(mEgl.eglGetError()));
if (maEGLconfigs[0] == null)
throw new RuntimeException("Error: eglConfig() not Initialized");
int[] attrib_list = { EGL_CONTEXT_CLIENT_VERSION,2,EGL10.EGL_NONE };
mEglContext = mEgl.eglCreateContext(mEglDisplay,maEGLconfigs[0],EGL10.EGL_NO_CONTEXT,attrib_list);
}
private void CreateSurfaceEGL(SurfaceTexture surfaceTexture,int height)
{
surfaceTexture.setDefaultBufferSize(width,height);
mEglSurface = mEgl.eglCreateWindowSurface(mEglDisplay,surfaceTexture,null);
if (mEglSurface == null || mEglSurface == EGL10.EGL_NO_SURFACE)
{
int error = mEgl.eglGetError();
if (error == EGL10.EGL_BAD_NATIVE_WINDOW)
{
Log.e(LOG_TAG,"Error: createWindowSurface() Returned EGL_BAD_NATIVE_WINDOW.");
return;
}
throw new RuntimeException("Error: createWindowSurface() Failed " + GLUtils.getEGLErrorString(error));
}
if (!mEgl.eglMakeCurrent(mEglDisplay,mEglSurface,mEglContext))
throw new RuntimeException("Error: eglMakeCurrent() Failed " + GLUtils.getEGLErrorString(mEgl.eglGetError()));
int[] widthResult = new int[1];
int[] heightResult = new int[1];
mEgl.eglQuerySurface(mEglDisplay,EGL10.EGL_WIDTH,widthResult);
mEgl.eglQuerySurface(mEglDisplay,EGL10.EGL_HEIGHT,heightResult);
Log.i(LOG_TAG,"EGL Surface Dimensions:" + widthResult[0] + " " + heightResult[0]);
}
private void DeleteSurfaceEGL(EGLSurface eglSurface)
{
if (eglSurface != EGL10.EGL_NO_SURFACE)
mEgl.eglDestroySurface(mEglDisplay,eglSurface);
}
