flypig.co.uk

I'm still in the process of trying to extract pixel colours from the surface used for transferring the offscreen buffer to the onscreen render. The snag I hit yesterday is that I wanted to use glGetTexImage(), but this symbol isn't being dynamically loaded for use with GLContext.

Consequently I've added it to the end of the coreSymbols table like this:

    const SymLoadStruct coreSymbols[] = {
        { (PRFuncPtr*) &mSymbols.fActiveTexture, {{ 
    "glActiveTexture", "glActiveTextureARB" }} },
        { (PRFuncPtr*) &mSymbols.fAttachShader, {{ "glAttachShader", 
    "glAttachShaderARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindAttribLocation, {{ 
    "glBindAttribLocation", "glBindAttribLocationARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindBuffer, {{ "glBindBuffer", 
    "glBindBufferARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindTexture, {{ "glBindTexture", 
    "glBindTextureARB" }} },
[...]
        { (PRFuncPtr*) &mSymbols.fGetTexImage, {{ "glGetTexImage", 
    "glGetTexImageARB" }} },

        END_SYMBOLS
    };

I've also searched through the rest of the code for glBindBuffer, which is the reference I'm using for how to introduce glGetTexImage. Although it comes up in many places in the code, none of them look relevant to what I'm doing, so I'm going to guess that the change I've made above is all that's needed.

At least I may as well build it and find out.

Now when I run it I get this:

Created LOG for EmbedLiteLayerManager
Can't find symbol 'glGetTexImage'.
Crash Annotation GraphicsCriticalError: |[0][GFX1-]: Failed to create 
    EGLConfig! (t=1.32158) [GFX1-]: Failed to create EGLConfig!
Segmentation fault

That's not a great sign. I'm going to have to put some more thought into this.

This error message appears twice in the code so I can't be entirely certain, but it looks like the error is resulting in a failure in the following method:

bool CreateConfig(EglDisplay& egl, EGLConfig* aConfig, int32_t depth,
                  bool aEnableDepthBuffer, bool aUseGles, int aVisual);

At this stage I'm not really sure what I'm doing, but I've changed my earlier change so it now looks like this:

    const SymLoadStruct coreSymbols[] = {
        { (PRFuncPtr*) &mSymbols.fActiveTexture, {{ 
    "glActiveTexture", "glActiveTextureARB" }} },
        { (PRFuncPtr*) &mSymbols.fAttachShader, {{ "glAttachShader", 
    "glAttachShaderARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindAttribLocation, {{ 
    "glBindAttribLocation", "glBindAttribLocationARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindBuffer, {{ "glBindBuffer", 
    "glBindBufferARB" }} },
        { (PRFuncPtr*) &mSymbols.fBindTexture, {{ "glBindTexture", 
    "glBindTextureARB" }} },
[...]
        { (PRFuncPtr*) &mSymbols.fGetTexImage, {{ "glGetTexImage" }} 
    },

        END_SYMBOLS
    };

Sadly after rebuilding, re-uploading and re-running, that didn't fix it. I'm out of ideas for today, but maybe after a good night's sleep I'll have some better ideas tomorrow. Let's see in the morning.

If you'd like to read any of my other gecko diary entries, they're all available on my Gecko-dev Diary page.