Layered rendering not working on Iris 6100

I'm trying to do layered rendering to a cube texture (render 6 instances, instance id -> layer id in vertex shader) but it doesn't seem to be working correctly on my 2015 rMBP with Intel Iris 6100 graphics. It seems to only be able to render to the first face (I can hard code the layer index in the shader to any value, but nothing will be drawn to any face but index 0).


I tested this on an iMac with an R9 M380 and it works as expected so I'm wondering if this is an Intel specific bug? Unfortunately I don't have access to a newer system with Intel graphics to confirm whether or not it only affects 5th gen hardware.


I've made a simple test program that renders the default cube from the Game project template to all 6 faces of a cube texture and then blits all the faces to the window. On the Intel machine all but the first image is blank, on the R9 machine all 6 show the spinning cube. I've filed bug report 31699592 where I've uploaded the sample project (I tried to post a link to it here but my post seemed to be stuck awaiting moderation while the link was present).


Thanks,


Evan

Replies

I've managed to test this on a new MBP with Intel HD 530/AMD Pro 460 GPUs and the problem again occurs on the Intel GPU but not the AMD so it's not just specific to 5th gen hardware.