It's faster to render once for every rectangle in the clip region than
rendering the outline of the clip region.
Especially because this reduces the time necessary to build up the frame
data.
In widget-factory (where we have 3 rectangles), this leads to a 5x
speedup in the rendering time rendering alone.
Snapshotting time goes from 10ms to ~1ms, which is another huge
improvement.
This way we can pass the command pool around.
And that allows us to allocate and submitcustom buffers.
And that is necessary to make staging images work.
By creating unlimited render objects, we would never wait on the GPU.
This would mean that if the GPU was the bottleneck, we would fill its
queue with render commands faster than it could process them.
And because the nvidia binary driver and my code work surprisingly well
and bugfree, this lead to exhaustion of RAM. I had 50GB of swap
configured and my hard disk was quicker as swap storage than my GPU was
at processing the commands, so stuff still filled up.
At that point my computer became rather unresponsive and I decided to
reboot it, so I that could write this patch.
And move the actual rendering code there.
A RenderPass is a collection of operations on the same target that
get executed one after another. It roughly targets VkRenderPass or
rather the subpasses of a VkRenderPass.
For now, only the infrastructure is there. No real stuff is happening.
This is refactoring work.
GskVulkanRender is supposed to be the global object for a render
operation, ie GskVulkanRenderer.render() will create this object for
what it does.
The object will be split into stages that perform the operations
necessary to create a drawing.
We can now upload vertices.
And we use this to draw a yellow background. Which is clearly superior
to not drawing anything.
Also, we have shaders now. If you modify them, you need glslc installed
so they can be recompiled into Spir-V bytecode.
