descriptorheap: fix image offset

[djdeath]

I noticed this while debugging why the demo doesn't render anything on Intel/Mesa.

There are 2 buffers and the code says the images are after the buffers.

[SaschaWillems]

Thank you very much for this PR!. This worked on my setup by accident, cause imageDescriptorAlignment is the same as uniformBuffers.size() * bufferDescriptorSize.

[spencer-lunarg]

... this is going to be the same bug 1000 people make, even with GPU-AV added, it will only help detect on the broken machine, might just be a documentation thing, not sure, but glad we fixed this here now since assume people will be using this example for time to come lol

[SaschaWillems]

Yeah, it's a common Vulkan problem that's a bit exaggerated here due to all the alignments, offsets, preserved sizes, etc. introduced in the heaps extension. I'm with you that this is something that can prob. only be mitigated by documentation. The guide chapter on heaps already helped me a lot with this sample, so maybe I can add some of my experience writing this sample to that chapter at some point.

[spencer-lunarg]

The guide chapter on heaps already helped me a lot with this sample, so maybe I can add some of my experience writing this sample to that chapter at some point.

Glad it helpped (I still re-reference it myself lol) ... anything you want to add to it you feel it "worth wild" that would be awesome!