* New experimental tone mapper
The new tone mapper proposed in this change replaces Uchimura (see
below) and is composed of two distinct algorithms:
- The first is the customizable compression curve from Timothy Lotte
(from GDC 2015). The curve's default parameters were chosen to
match the overall appearance (contrast) of the ACES curves used
as our current default tone mapper. This was done to provide a
good migration path to making this new solution the default in
a future version of Filament.
The compression curve can be customized via its contrast, shoulder,
input middle gray, output middle gray, and maximum "HDR value"
(scene referred).
It is important to note that the compression is only applied to
the luminance of the input scene referred value.
- The second is a novel approach by Troy Sobotka called Exposure
Value Invariant Luminance Scaling (or EVILS). This solution works
on the largest chromatic channel of the input value as opposed
to mapping all RGB channels as we do in our other tone mappers.
The algorithm effectively scales all channel by a ratio that
depends on both the compressed luminance from the first stage
and the luminance of input value normalized by the largest
channel.
This new solution offers important benefits as it manages to
preserve chromaticity for high input values. It is also designed
to provide a desirable rolloff to white on overexposure. This
means that even without gamut mapping, this solution avoids many
hue skews (red to orange, blue to purple, etc.). The results
provided by this solution are much more natural and make using
other color grading tools much easier.
* Use std::pow instead of pow
* Fix Web builds
The focal length slider now works over a remote connection. Also, the
slider for focus distance now controls the value in `ViewerSettings`
(which gets applied to Camera) rather than the value in
`DepthOfFieldOptions` (which is deprecated).
- Use lower depth LOD as the cone radius increases.
This is the same technique we use for SAO.
The better cache access significantly improve performance.
On a test on Pixel4 at 585MHz, SAO pass improves by 30%.
This also helps the algorithm scale with the shadow distance.
- Shadow direction/length no longer dependent on aspect-ratio and camera
orientation.
This is fixed by doing all the computations in screen-space instead of
normalized screen space.
- Shadow parameters are no longer dependent on the field of view.
- Also rename dominantLightShadowing.fs to ssct.fs
- remove zoom parameter, it wasn't very useful.
This introduces the `viewer::Settings` struct, and a JSON reader /
writer.
This will be used for automated testing and for client / server
communication.
Note that `viewer::Settings` is closely associated with the
`filament::View` API; when updating the latter we will often need to
update the former, as well as some serialization code. This increases
the maintenance burden and I think we should consider using a parser
library like libclang or a macro-based reflection utility.
This PR also migrates SimpleViewer into libs/viewer and un-inlines its
implementation. It does not belong in gltfio because it has an imgui
dependency.
Mathias Agopian
Romain Guy
Philip Rideout
Ben Doherty
Pixelflinger