Ogre ecosystem roundup #8

following the last post about what is going on around Ogre, here is another update. With the Ogre 13.1 release, mainly the usability of Ogre was improved with the following additions.

Ogre 13.1 release

The per-pixel RTSS stage gained support for two sided lighting. This is useful if you want to have a plane correctly lit from both sides or for transparency effects, as shown below:

single sided/ two-sided lighting

Furthermore, PCF16 filtering support was added to the PSSM RTSS stage. This gives you softer shadows at the cost of 4x the texture lookups. The images below show crops from the ShaderSystem sample at 200% highlighting the effect

PCF4/ PCF16

blender2ogre improved even further

Thanks to the continued work by Guillermo “sercero” Ojea Quintana, blender2ogre gained some exciting new features.

The first is support for specifying Static and Instanced geometry like this. You might wonder whether you should be using that and if yes, which variant. Therefore, he also collected the respective documentation which is available here.

The second notable feature is support for .mesh import, which might come handy if you are modding some Ogre based game or just lost the source .blend file. This feature is based on the respective code found in the Kenshi Blender Plugin (which in turn is based on the Torchlight plugin).

Then, old_man_auz chimed in and fixed some bugs when exporting to Ogre-Next, while also cleaning up the codebase and improving documentation.

Finally, yours truly added CI unit-tests, which make contributing to blender2ogre easier.

OpenAL EFX support in ogre-audiovideo

Again, contributed by sercero are some important additions to the audio part of the ogre-audiovideo project which drastically improve the useability.

The first one is that you no longer need boost to enable threading. OgreOggSound will now follow whatever Ogre is configured with.

The second one is being able to use EFX effects with openal-soft instead of the long-dead creative implementation. This enables effects like reverb or bandpass filters.

Read more in the release-notes. This release was too, done by sercero which kindly took the burden of co-maintaining the project.

Ogre 13 released

We just tagged the Ogre 13 release, making it the new current and recommended version. We would advise you to update wherever possible, to benefit from all the fixes and improvements that made their way into the new release.
This release represents 2.5 years of work from various contributors when compared to the previous major 1.12 release. Compared to the last Ogre minor release (1.12.12), however we are only talking about 4 months. Here, you will mainly find bugfixes and the architectural changes that justify the version number bump.

For source code and pre-compiled SDKs, see the downloads page.

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Ogre ecosystem roundup #7

following the last post about what is going on around Ogre, here is another update. With the Ogre 1.12.12 release, mainly the usability of Ogre was improved with the following additions.

Ogre 1.12.12 release

The last 1.12 release had some serious regressions in D3D9 and GL1, therefore I scheduled one more release in the 1.12.x series.

Updated release notes

As the Ogre 1.12 series was an LTS release, many important features landed after the initial 1.12.0 release. To take this into account and to give an overview which version you need, the “New and Noteworthy” document was updated with the post .0 additions. (search for “12.” to quickly skim through them).

Nevertheless, there are also some new features in the 1.12.12 release itself:

Cubemap support in compositors

Compositors render targets can now be cubemaps by adding the cubic keyword to the texture declaration – just like with material texture_units.

To really take advantage of this, you can now also specify the camera to use when doing render_scene passes. This way any camera in your scene can be used as an environment-probe for cube mapping.

Finally, to really avoid touching any C++, there is now the align_to_face keyword which automatically orients the given camera to point to the targeted cubemap face.

See this commit on how these things can simplify your code and this for further documentation.

Terrain Component in Bindings

Thanks to a contribution by Natan Fernandes there is now initial support of the Terrain Component in our C#/ Java/ Python bindings.

Python SDK as PIP package

Python programmers can now obtain a Ogre SDK directly from PyPI as they are used to with:

pip install ogre-python

Just as the MSVC and Android SDKs, it includes the assimp plugin which allows to load almost any mesh format and ImGui, so you can create a UI in a breeze.
For now only Python 3.8 is covered – but on all platforms. This means you can now have a pre-compiled package for OSX and Linux too.

Improved blender2ogre

Thanks to some great work by Guillermo “sercero” Ojea Quintana, the blender2ogre export settings are much more user friendly now:

On top of having some context what a option might do, the exporter can now also let Ogre generate the LOD levels. This gives you the choice to

  • Iteratively apply blender “decimate” as in previous releases. This will generate one .mesh file per LOD level, but may result in a visually better LOD
  • use the Ogre MeshLOD Component. This will store all LOD levels in one .mesh file, only creating a separate index-buffer per LOD. This will greatly reduce storage compare to the above method.

SceneNode animations

But he did not stop there, blender2ogre now also exports NodeAnimationTrack based animations. To this end it follows the format introduced by EasyOgreExporter, so both exporters are compatible to each other.

To formalise this, he even extended the .scene type definition, so other exporters implementing this function can validate their output.

Needless to say, he also extended the DotScene Plugin shipped with 1.12.12 to actually load these animations.

.scene support in ogre-meshviewer

Picking up the work by Guillermo, I exteded ogre-meshviewer to load .scene file – in addition to .mesh files and whatever formats assimp knows about.

However, for now it will merely display the scene – there are no inspection tools yet.

Ogre 1.12.11 released

Ogre 1.12.11 was just released. This is the last scheduled release for the 1.12 series and contains many bugfixes and new features. The smaller ones are:

The more notable new features will be presented in more detail in the following

Support for animated particles

Support for animating particles via Sprite-sheet textures was added. This enables a whole new class of effects with vanilla Ogre that previously required using particle-universe.

On the screenshots above, you see the Smoke demo, that was updated to showcase the new feature. However, the screenshots do not do full justice to the feature. If you are interested, it is best to download the SampleBrowser build and see the effect in action.

See this post (targeting blender) for an overview of the general technique.

For running the animation, the new TextureAnimator Affector was added.

While at it, I fixed several bugs deep in Ogre that prevented ParticleSystems to be properly treated as shadow casters. Now you can call setCastShadows as with any other entity and things will just work (see last image).

Software RenderSystem

Did you ever want to launch a Python Interpreter from your Shader or make HTTP requests per-pixel? Well, the wait is finally over – with the new TinyRenderSystem in Ogre 1.12.11 you can.

This render-system is based on the tinyrenderer project, which implements a full software-rasterizer in ~500 loc. If you are curious on how OpenGL works internally, I highly recommend taking a closer look.
For Ogre this had to be doubled to about ~1350 loc, but compared to the Vulkan RenderSystem from 2.x at ~24000 loc it is still tiny (note that this is already after stripping down the v2.3 implementation).

So what do we gain by having that RenderSystem? First it is a nice stress-test for Ogre, as this is a backend implemented in Ogre itself; each Buffer uses the DefaultBuffer implementation and each Texture and RenderWindow is backed by an Ogre::Image.
This makes it also a great fit for offline conversion tools, that want full access to the resources, without needing to actually access the GPU.

Next, this is really useful if you want to Unit-Test a Ogre-based application. Typically, you would need to set-up a headless rendering server (more on that below) to merely check whether your triangle is centered correctly in the frame. This is super easy now.

The screenshots on top, taken from the SampleBrowser, show you how far you can actually get with the RenderSystem. Note that there is no alpha blending, no mipmapping, no user-provided shaders and generally no advanced configuration of the rasterization. So if you are after full-featured software rasterization, you are better off with OpenGL on MESA/llvmpipe.

However, if you want to experiment with the rendering pipeline without being bound by the OpenGL API, this is the way to go. You actually can do the HTTP requests per pixel ;). Also, for creating a new RenderSystem, this is the least amount of reference code to read.

Transparent headless mode on Linux

Rendering on a remote machine over ssh just got easier! Previously ogre required a running X11 instance, which can be a hassle to come by on a machine without any monitors attached (e.g. a GPU server).

Instead of bailing out, Ogre will now merely issue a warning and transparently fall-back to a PBuffer based offscreen window. See this for the technical background.

To be able to do so Ogre must be using EGL instead of GLX, to do so it must be compiled with OGRE_GLSUPPORT_USE_EGL=1. With 1.13, we will be using EGL instead of GLX by default.

Compared with the EGL support recently added in v2.2.5, the implementation is much simpler and does provide any configuration options – but on the plus side the flag above is the only switch to toggle to get it running.

Improved Bullet-Ogre integration

I added a simplified API to the btogre project.

https://github.com/OGRECave/btogre

If you want to have physics on top of your rendering, it is now as simple as:

auto mDynWorld = new BtOgre::DynamicsWorld(gravity_vec);
mDynWorld->addRigidBody(weight, yourEntity, BtOgre::CT_SPHERE);

where (as in Bullet) a weight of 0 means static object. Now you can call

mDynWorld->getBtWorld()->stepSimulation(evt.timeSinceLastFrame);

and your objects will interact with each other. Of course if you need more control, the unterlying bullet types are still fully exposed.

Oh, and python bindings are now available too.

Augmented Reality made simple – with Ogre and OpenCV

As a small Christmas present, I want to show you how easy it has become to make Augmented Reality yourself thanks to Ogre and OpenCV. You should know that my other interest, besides graphics, lies with Computer Vision.
The demo will not rely on proprietary solutions like ARCore or ARKit – all will be done with open-source code that you can inspect an learn from. But lets start with a teaser:

This demo can be put together in less than 50 lines of code, thanks to the OpenCV ovis module that glues Ogre and OpenCV together. Next, I will briefly walk you through the steps that are needed:

First, we have to capture some images to get by the Reality part in AR. Here, OpenCV provides us an unified API that you can use for your Webcam, Industrial Cameras or a pre-recorded video:

import cv2 as cv

imsize = (1280, 720) # the resolution to use
cap = cv.VideoCapture(0)
cap.set(cv.CAP_PROP_FRAME_WIDTH, imsize[0])
cap.set(cv.CAP_PROP_FRAME_HEIGHT, imsize[1])

img = cap.read()[1] # grab an image

then, we have to set up the most crucial part in AR: camera tracking. For this, we will use the ArUco markers – the QR-like quads that surround Sinbad. To no surprise, OpenCV comes with this vision algorithm:

adict = cv.aruco.Dictionary_get(cv.aruco.DICT_4X4_50)
# extract 2D marker-corners from image
corners, ids = cv.aruco.detectMarkers(img, adict)[:2]
# convert corners to 3D transformations [R|t]
rvecs, tvecs = cv.aruco.estimatePoseSingleMarkers(corners, 5, K, None)[:2]

If you look closely, you see that we are using a undefined variable "K" – this is the intrinsic matrix specific for your camera. If you want precise results, you should calibrate your camera to measure those. For instance using the web-service at calibdb.net, which will also just give you the parameters, if your camera is already known.

However, if you just want to continue, you can use the following values that should roughly match any webcam at 1280x720px

import numpy as np
K = np.array(((1000, 0, 640), (0, 1000, 360), (0, 0, 1.)))

So now we have the image and the according 3D transformation for the camera – only the Augmented part is missing. This is where Ogre/ ovis come into play:

# reference the 3D mesh resources
cv.ovis.addResourceLocation("packs/Sinbad.zip")
# create an Ogre window for rendering
win = cv.ovis.createWindow("OgreWindow", imsize, flags=cv.ovis.WINDOW_SCENE_AA)
win.setBackground(img)
# make Ogre renderings match your camera images
win.setCameraIntrinsics(K, imsize)
# create the virtual scene, consisting of Sinbad and a light
win.createEntity("figure", "Sinbad.mesh", tvec=(0, 0, 5), rot=(1.57, 0, 0))
win.createLightEntity("sun", tvec=(0, 0, 100))
# position the camera according to the first marker detected
win.setCameraPose(tvecs[0].ravel(), rvecs[0].ravel(), invert=True)

You can find the full source-code for the above steps, nicely combined into a main-loop over at OpenCV.

To record the results, you can use win.getScreenshot() and dump it into a cv.VideoWriter – contrary to the name, this works in real-time.

Extending the above code to use cv.aruco.GridBoard as done in the teaser video is left as an exercise for the reader as this is more on the OpenCV side.

Also, If you rather want to use ARCore on Android, there is a Sample how to use the SurfaceTexture with Ogre. Using this, you should be able to modify the hello_ar_java sample from the arcore-sdk to use Ogre.