Question

I have an app with a number of render targets/frame buffers and inside one call to glDrawElements it crashes on device ( iPad iOS 5.0) but not in simulator. This is a very shader intensive app with a dozen different shaders and thousands of vertex buffers.

Further debugging the matter turned me to believe that the crash occurs because of a particular shader, but the shader is valid and so is the frame buffer object that is being written to.

Answer 1

Ok, so after tons of time spent on debugging I found out that my Depth of field shader was causing the crash, particularly this function :

float GetNearFalloff( float Depth, float MinDist, float MaxDist)
{
    float Range = MaxDist - MinDist;
    if (Depth < MinDist)
        return 1.0;
    /*else*/if (Depth > MaxDist)
        return 0.0;

    float Blur = 1.0 - ( (Depth - MinDist) / Range );
    return Blur;
}

Basically the commented else there is causing my crash. Removing that made everything work. I put it back actually ( I was thinking it may be something else ), only to see that after a couple of shader recompilations the same crash appeared with the same fix, deleting the else.