Previously, only forward basis distance from the camera was used.
This means that unnecessarily high LOD levels were used for objects located to the side of the camera.
The distance from the camera origin is now used, independently of direction.
This removes the countless small UBO writes we had before
and replaces them with a single large write per render pass.
This results in much faster rendering on low-end devices
but improves speed on all devices.
The flag INSTANCE_DATA_FLAG_MULTIMESH is used for both multimesh and particles instances, this commit adds a new INSTANCE_DATA_FLAG_PARTICLES flag to discriminate between them.
This flag will also be used in the future to properly support TAA in particles.
Instead of updating all viewports, then blitting all viewports
to the backbuffer, then swapping all buffers, we run through
all viewports and render, blit, and swap backbuffer before
going to the next viewport.
Fixes include using proper depth buffer format in 3D (this had previously been fixed already but the changes were lost in a rebase), Remove unused lighting and shadowing code in 2D, and update 2D UBOs using glBufferSubData so that they remain the appropriate size.
Using this command:
```
find -name "thirdparty" -prune -o -name "*.h" -exec sed -i {} -e '/return /! s/\t\([A-Za-z0-9_]* \*[A-Za-z0-9_]*\)\;/\t\1 = nullptr;/g' \;
```
And then reviewing the changes manually to discard the ones that don't
seem correct/safe/good (notably changes to `core` unions).
This allows light sources to be specified in physical light units in addition to the regular energy multiplier. In order to avoid loss of precision at high values, brightness values are premultiplied by an exposure normalization value.
In support of Physical Light Units this PR also renames CameraEffects to CameraAttributes.
Per-light energy gives more control to the user on the final result of
volumetric fog. Specific lights can be fully excluded from volumetric fog
by setting their volumetric fog energy to 0, which improves performance
slightly. This can also be used to prevent short-lived dynamic effects
from poorly interacting with volumetric fog, as it's updated over several
frames by default unless temporal reprojection is disabled.
Volumetric fog shadows now obey Light3D's Shadow Opacity property as well.
The shadow fog fade property was removed as it had little visible impact
on the final scene's rendering.
