Fix renderers can't batch vertices with the same blending parameters in some cases

[EVAST9919]

Consider the following scenario.
You may assume that these boxes will be batched and drawn in a single draw call, however this is not the case:

That's because each DrawNode sets its blending parameters inside Draw method and the problem here is that CompositeDrawNode does the same. But this is not needed since each child will set their own blending later on (which is computed with DrawColourInfo and inherited from the parent), thus making blending update inside composite practically useless.
Result (both boxes drawn together):

[peppy]

Are those red triangle overlays a new thing you added? If you can make that available via the draw vis or otherwise that seems super helpful to see where batching is being broken. ie. they are drawn across the whole screen content, colour changes for each batch game-wide.

[smoogipoo]

Makes sense to me, can't immediately imagine a breaking scenario.

[EVAST9919]

Are those red triangle overlays a new thing you added? If you can make that available via the draw vis or otherwise that seems super helpful to see where batching is being broken. ie. they are drawn across the whole screen content, colour changes for each batch game-wide.

I'm using NVIDIA Nsight Graphics for draw calls inspection. I agree that it would be nice to have something similar inside the framework, however at the current moment I have no idea if that's possible. I will take a look though.