PCC / VCT hybrid progress

Last time I mentioned we were working on PCC / VCT Hybrid (PCC = Parallax Corrected Cubemaps, VCT = Voxel Cone Tracing).

I just implemented storing depth into the alpha channel, which is used to improve the quality of the hybrid.

Because we often use RGBA8 cubemaps, 8-bits is not enough to store the depth. Therefore we only store the deviation from the ideal probe shape.

The original PCC algorithm boils down to:

    posInProbeShape = cameraCenter + reflDir * fDistance;

Where cameraCenter is artist-defined (where the PCC camera was placed to build the probe) and posInProbeShape is also artist-defined (by controlling the size of the probe)

PCC is about finding reflDir mathematically:

    reflDir = (posInProbeShape - cameraCenter) / fDistance;

However we already know reflDir after executing PCC’s code.

Now the depth compression comes to effect by slightly altering the formula:

    realReconstructedPosition = cameraCenter + reflDir * fDistance * depthDeviation;

The variable depthDeviation is in range [0; 2] (which we store in the alpha channel) and thus 8-bit should be enough.

Technically this could introduce a few artifacts because we only store the depth in range [0; maximum_distance * 2]

Storing the depth deviation dramatically improves the hybrid’s quality!

But let’s not rush.

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Voxel Cone Tracing

Over the last couple months we have been working on Voxel Cone Tracing (VCT), a Global Illumination solution.

Voxel Cone Tracing could be seen as an approximated version of ray marching.

The scene is voxelized and three voxels are generated, containing albedo, normals and emissive properties. In other words, we build a Minecraft-looking representation of the world:

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New build scripts for 2.1 and 2.2!

We’ve often been told building Ogre from source is hard.

And they’re right!

Which is why we tried our best and prepared quick start scripts that will clone all necessary dependencies, configure CMake and build for you!

Grab the download scripts:

Unzip them and run the script that matches your platform and OS!

For example if you’re on Windows and have Visual Studio, run either:

  • build_ogre_Visual_Studio_15_2017_Win32.bat
  • build_ogre_Visual_Studio_15_2017_x64.bat

depending on the architecture you want to build for (e.g. 32-bit vs 64-bit)

The scripts will automatically start building, but you will also find the Visual Studio solution files under Ogre/build/OGRE.sln

If you’re on Linux, run either:

  • ./build_ogre_linux_c++98.sh
  • ./build_ogre_linux_c++11.sh
  • ./build_ogre_linux_c++latest.sh

Which one you need depends on the C++ version you’re targetting. C++98 compiles much faster than the rest, but may have incompatibilities (particularly with std::string) if mixed in a project build for C++11 or newer

There are currently no build scripts for Apple ecosystem. For building for iOS, refer to the Setting up Guide. The instructions for Linux should work for building for macOS, but may require additional manual intervention.

We hope this makes your life easier! And let us know if you encounter problems with these scripts! The goal is that building Ogre from scratch becomes as simple as tapping a few clicks.

Further discussion on forum post.

Progress Report July 2019

Hoo boy! This report was scheduled for January but couldn’t be released on time for various reasons.

We have another report coming as this is old news already! We have another report coming mostly talking about VTC (Voxel Cone Tracing) which is a very interesting feature that has been in development during this year.

But until then, let’s talk about all the other features that have been implemented so far!

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2.2 branch no longer WIP

If you’re tracking our repo you may have observed we renamed the v2-2-WIP branch into v2-2

What does this mean?

It means the branch is stabilizing. Back when it was v2-2-WIP, it was very unstable. Checking out that branch meant you could find crashes, memory leaks, missing or broken features; and the API interface was changing very quickly, thus updating the repository could mean your code would no longer compile and required adapting.

Over the last couple months, the API interfaces on 2.2 had begun to settle down, bugs were fixed and there were no apparent leaks. In fact some teams started already using it.

Now that it is no longer WIP, while there could still be API breakage on the 2.2 branch or accidental crashes/regressions, it shouldn’t be anything serious or that requires intensive porting.

We still have a few missing features (such as saving textures as DDS) but they’re not used frequently.

Coming up next

We still owe you a Progress Report of what’s been going on in 2.1 and 2.2 in the past year and a half; we have that written down but still needs a few reviews.

Coming up next is:

  • More real time GI improvements
  • VR performance optimizations
  • We are planning on a Vulkan/D3D12 backend

Additionally we have a community member working on GPU-driven rendering and GPU particle FXs; while another community member just contributed Morph animations to 2.1

Yes, Morph animations are finally HW accelerated again! We are evaluating on porting this contribution to 2.2; it shouldn’t take long but we’re evaluating if it can be improved with the use of Compute Shaders

What about Ogre 2.1?

If someone wants to teach Matias aka dark_sylinc a quick automated way to create installer SDKs, that is welcomed! (he never liked handling that!!!)

Ogre 2.1 has been very stable. Eugene ported several improvements from the 1.x branch; and we currently are dealing with a regression that caused due to how PF_BYTE_LA / PF_L8 format is treated in D3D11, but other than that 2.1 is ready for release.

The morph animation contribution is brand new so that may need a bit more testing.

If you don’t see an SDK that is mostly due to time and knowledge to package an SDK.

If someone else wants to step in and maintain packaging, that is welcomed!

Further discussion in the Forum Post