eglChooseConfig() succeeds, but eglCreateContext() claims bad config.

[thomas_albertin]

I'm having trouble getting EGL to produce an OpenGL context for me. All the functions return no errors except eglCreateContext() which returns EGL_NO_CONTEXT, and eglGetError() produces the code for EGL_BAD_CONFIG. eglChooseConfig() produces no error.

I have some experience with OpenGL, but I've never had to create my own context before, so maybe I've missed something important.

I looked through the forums for a similar question and found this this post. I was struck by how similar his code looked to mine. He says that it works, but mine does not, and I can't see any meaningful difference.

Here's my code, stripping error checking to be concise:

/*
 * EGL Initialization
 * Creates OpenGl context
 */

/* This part lives in a header */
struct gl_details {
    GLuint vShader;
    GLuint fShader;
    EGLDisplay display;
    EGLConfig config;
    EGLSurface surface;
    EGLContext context;
    EGLNativeDisplayType nDispType;
    EGLNativeWindowType nWinType;
};
struct gl_details glDetails;

/* The rest lives in the .c file */ 
glDetails->nDispType = fbGetDisplayByIndex(0);
glDetails->display = eglGetDisplay(glDetails->nDispType);

eglInitialize(glDetails->display, NULL, NULL)
eglBindAPI(EGL_OPENGL_ES_API)

/* This is the part where I'm most suspicious. */
static const EGLint fb_attribute_list[] = {
    EGL_RED_SIZE, 5,
    EGL_GREEN_SIZE, 6,
    EGL_BLUE_SIZE, 5, 
    EGL_ALPHA_SIZE, 0,
    EGL_SAMPLES, 0,
    EGL_DEPTH_SIZE, 24,
    EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
    EGL_SURFACE_TYPE, EGL_WINDOW_BIT, 
    EGL_NONE /* EGL null terminator */
};
EGLint configResults = 0;
eglChooseConfig(glDetails->display, &fb_attribute_list[0], &(glDetails->config), 1, &configResults)

glDetails->nWinType = fbCreateWindow(glDetails->nDispType, 0, 0, g_DsyInfo.fb_W, g_DsyInfo.fb_H);
glDetails->surface = eglCreateWindowSurface(glDetails->display, glDetails->config, glDetails->nWinType, NULL);

EGLint const context_attrib_list[] = {
    EGL_CONTEXT_CLIENT_VERSION, 2,
    EGL_NONE
};
glDetails->context = eglCreateContext(glDetails->display, glDetails->config, EGL_NO_CONTEXT, context_attrib_list);

eglMakeCurrent(glDetails->display, glDetails->surface, glDetails->surface, glDetails->context);
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If anyone can see what I've done wrong, or even can tell me how to get better output for debugging, it would be much appreciated.

[Bio_TICFSL]

Hi Thomas,

Is difficult is you not show the error but  perform standard EGL initialization steps. Create EGL context from the ANativeWindow* pointer:

EGLint              numConfigs;

        EGLint              majorVersion;

        EGLint              minorVersion;

        EGLConfig           eglConfig;

        EGLContext          eglContext;

        EGLSurface          eglSurface;

        EGLDisplay          eglDisplay

static const EGLint contextAttribs[] =

    {

        EGL_CONTEXT_CLIENT_VERSION, 2,

        EGL_NONE

    };

        static const EGLint configAttribs[] =

    {

     EGL_SAMPLES,      0,

     EGL_RED_SIZE,     5,

     EGL_GREEN_SIZE,   6,

     EGL_BLUE_SIZE,    5,

     EGL_ALPHA_SIZE,   0,

     EGL_DEPTH_SIZE,   0,

     EGL_SURFACE_TYPE, EGL_WINDOW_BIT,

     EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,

     EGL_NONE

    };

EGLint              w;

        EGLint              h;

eglBindAPI(EGL_OPENGL_ES_API);

        eglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY); 

        eglInitialize(eglDisplay, &majorVersion, &minorVersion);                

        eglGetConfigs(eglDisplay, NULL, 0, &numConfigs);               

        eglChooseConfig(eglDisplay, configAttribs, &eglConfig, 1, &numConfigs);

  ANativeWindow* anw = CameraHardwareInterface::getANativeWindow(mNativeWindow);                      

        eglCreateWindowSurface(eglDisplay, eglConfig, anw, NULL);     

        eglContext = eglCreateContext(eglDisplay, eglConfig, EGL_NO_CONTEXT, contextAttribs);

  eglMakeCurrent(eglDisplay, eglSurface, eglSurface, eglContext);

  eglQuerySurface(eglDisplay, eglSurface, EGL_WIDTH, &w);

  eglQuerySurface(eglDisplay, eglSurface, EGL_HEIGHT, &h);

Regards

[thomas_albertin]

Update: swapped out eglChooseConfig with eglGetConfigs so I could see if any of the configs were acceptable. All 70 configs failed.