imx6 GPU 后台离屏绘制3D图_eglbindapi与eglinitialize流程-优快云博客

本文链接：https://blog.youkuaiyun.com/ruhailiu126/article/details/85125126

这篇博客介绍了如何在imx6 GPU上使用c++进行后台离屏渲染3D图，并将结果存储为图片。关键步骤包括初始化EGL配置，创建Pbuffer Surface，编译和链接OpenGL ES着色器，进行3D图绘制，最后通过glReadPixels获取渲染结果并保存为PNG文件。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

fsl的官方资料可以作为参考：https://download.youkuaiyun.com/download/ruhailiu126/10864713

官方并未提供offscreen离屏渲染例子

以下采用c++操作，后台离屏将3D图存储为图片。关键代码记录笔记如下：

初始化：

static const EGLint s_configAttribs[] =
    {
        EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
        EGL_RENDERABLE_TYPE,EGL_OPENGL_ES2_BIT,
        EGL_RED_SIZE,  8,
        EGL_GREEN_SIZE, 8,
        EGL_BLUE_SIZE,  8,
        EGL_ALPHA_SIZE, 8,
   //   # EGL_SAMPLES,  0,
        EGL_NONE
    };

EGLint numconfigs;

    eglNativeDisplayType = fsl_getNativeDisplay();
    egldisplay = eglGetDisplay(eglNativeDisplayType);
    eglInitialize(egldisplay, NULL, NULL);
    assert(eglGetError() == EGL_SUCCESS);
    eglBindAPI(EGL_OPENGL_ES_API);

    eglChooseConfig(egldisplay, s_configAttribs, &eglconfig, 1, &numconfigs);
    assert(eglGetError() == EGL_SUCCESS);
    assert(numconfigs == 1);

eglNativeWindow = fsl_createwindow(egldisplay, eglNativeDisplayType);
assert(eglNativeWindow);

#if 0
    eglsurface = eglCreateWindowSurface(egldisplay, eglconfig, eglNativeWindow, NULL);
#else
    EGLint attribListPbuffer[] = {
            // The NDK code would never draw to Pbuffer, so it's not neccessary to
            // match anything.
            EGL_WIDTH, width,
            EGL_HEIGHT, height,
            EGL_NONE };
    eglsurface = eglCreatePbufferSurface(egldisplay,eglconfig,attribListPbuffer);
#endif

assert(eglGetError() == EGL_SUCCESS);
EGLint ContextAttribList[] = { EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE };

    eglcontext = eglCreateContext( egldisplay, eglconfig, EGL_NO_CONTEXT, ContextAttribList );
    assert(eglGetError() == EGL_SUCCESS);
    eglMakeCurrent(egldisplay, eglsurface, eglsurface, eglcontext);
    assert(eglGetError() == EGL_SUCCESS);

   GLuint texture,renderBuffer,frameBuffer;
   glActiveTexture(GL_TEXTURE0);
   glGenTextures(1,&texture);
   glBindTexture(GL_TEXTURE_2D,texture);
   glPixelStorei(GL_UNPACK_ALIGNMENT,1);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE,pImageData);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

   glGenFramebuffers(1, &frameBuffer);
   glGenRenderbuffers(1, &renderBuffer);
   glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
   glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer);
   glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA4, width,height);
   glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
          GL_RENDERBUFFER, renderBuffer);

   if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
   {
          qDebug()<<"Image Handler initImageFBO failed!\n";
          return -1;
   }

{
glViewport(0,0,width,height);

// Compile the shaders