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With so much stuff – where to start? The fine new “little things” that would justify an entire release for some other software manufacturers or the big chunk? Suggestion – in order to be able to devote ourselves undisturbed to these chunks aka the new animation system, Feathers and Solaris/Karma updates, let’s take a look at the “sideshows” first and free up a lot of mental working memory.
Texture Mask Paint SOP aka Houdini 3D Painter
Houdini has long allowed masks and attributes to be painted directly onto the mesh, but until now only on the basis of topology. If you want to paint detailed masks, you need a correspondingly high-resolution mesh. The new Texture Mask Paint SOP, on the other hand, works on a UV basis and is therefore completely independent of the topology.
The interactive tool not only offers the expected paint function, but also brush features that are more familiar from specialists such as Photoshop or Substance Painter. The applied brushstrokes can be softened with Smooth or smudged with Smudge. Texture and Stamp allow you to paint with textures, while Dirt and Cloud loosen up the brushstroke with noises. The whole thing also works symmetrically.
The painting can be output as a volume mask based on the UVs, which can be used for any other purpose with the usual volume tools or simply used as a mask for the new Feather tools, for example. Alternatively, the volume mask can be exported via Heightfield-Ouptut as .exr and co. and used as a texture mask for hairgen/grooming or shading, for example. The appropriate node for scattering points into the freshly painted mask is called Scatter in Texture Mask and is able to understand the opacity or luminance of the paint node as a density multiplier. If you want to go deeper with the brush, you can use the free HPaint HDA(is.gd/hpaint) by Aaron Smith, a Houdiniesque version of the Grease Pencil.
Quad Remesh
Long wished for and finally here – a native Quadremesher. Although it is still in beta, it already delivers very good and, above all, very fast results. As soon as the node has the first remesh after a few seconds, the number of polygons can be changed almost in real time. Guides can currently only be created indirectly, but this will certainly change in the final version. Until then, you can draw a curve on the mesh, calculate the tangent using polyframe or orientalongCurves and then transfer it back as a guide attribute.
Clouds
If the current weather isn’t cloudy enough for you, you can use the completely new cloud tools to create hyper-detailed hero clouds or even an entire skybox full of clouds. A Cloud Shape Noise serves as the basis for the former, which can either be fed with any geometry or create a structure close to the shape of a cloud itself. This basic shape is ripped apart, processed and transformed into a realistic cloud using new cloud noises (Cloud Billowy & Cloud Wispy Noise), which were created from the detailed analysis of real cloud structures. As these are classic volumes, any Houdini tool can be used to further customise the shape.
The clouds generated in this way can be rendered physically accurately using the new cloud shader with multiscattering. If you want to go a little faster and don’t want to be completely precise, you can use the Cloud Ambient Occlusion Shader, which delivers very useful results for background clouds with a much faster rendering time.
The skybox is similarly direct, with a choice between 2D skyfields and 3D clouds. The former are configured with the new Skyfield plus Skyfieldpattern node, which comes with various cloud type presets, and then designed using the Skybox node. The Skybox alone is sufficient for 3D clouds. The cloud nodes mentioned above offer the option of applying further deformations.
Bubble Solver
A by-product of the new cloud tools is the bubble solver, which takes care of the correct interaction of bubbles. Overlaps are avoided and the individual bubbles are pressed against each other and deformed accordingly. As input, the node requires nothing more than a point cloud (particle, cloud generator or simply a grid) with the Pscale attribute set.
Ripple Solver
Another very simple tool (almost too simple for Houdini) for simulating wave movements on geometry, for example the effect of raindrops on water, but also the impact of shock waves on character. The waves can be output as a float attribute for further use in shading or can be used for other purposes, for example as a density attribute for scattering.
Solaris/Karma
The most important innovation here is the gold status of Karma XPU. The beta status has been cancelled and a whole host of new abilities have been added. These include the complete Light Filter Shader Set, Round Edges, Thin Wall (see Bubble Solver section), production boosters such as Cryptomatte and Deep Images, Absorption and Nested Dielectrics, faster First-Time-To-Pixel and generally increased speed, especially for Fur and Volumes. To be able to marvel at the latter, the render gallery now comes with an extensive statistics panel.
To go with the new Cloud Set, there is finally a Physical Sky (Hosek et al), which in principle combines the new Sky Dome Light Lop with a Distant Light under the bonnet and thus offers the usual Houdini flexibility – if desired. A lot has also happened in the area of shaders and material management. The new material library integrated in the material linker is a good way of creating a material collection more easily and assigning it via drag’n’drop. Some presets and access to the AMD Mtx library (online access) are included out of the box, but could be a little more user-friendly. If you are looking for an intuitive alternative, you can take a look at ODTools with its extensive asset library – is.gd/shelf_tools.
The Karma Material Builder has been tidied up and is now equipped with the Geometry Properties Node to save time. A new fur shader offers settings for medulla manipulation, the inner core of the hair, so to speak, which in turn promises realistic lightscattering.
As MaterialX is subject to constant growth and change and some essential (Uber) nodes are missing or have to be put together yourself, SideFX has thankfully supplied a whole host of new custom nodes, e.g. a ramp node. Fog Box (Uniform Volume for fog and other atmospheric effects), Background Plate, Ocean Procedural and Tone Mapping (Reinhardt and co.) also make it possible to work faster with XPU.
The new cloning offers the option of rendering and comparing the scene in parallel at different times or settings, for example to adjust the effect of a light at the beginning and end of a shot – temporally at the same time, so to speak. The Solaris toolset has also been optimised in many areas and offers, for example, the latest ACES support (applies to all areas of Houdini, not just Solaris), new lighting views and the RBD Desctruction LOP, a procedural that transforms RBD pieces at render time. Mplay can now export video formats natively without an FFmpeg installation, and not just from Solaris.
With its seamless integration, Karma can therefore be used very well as a production renderer and not only saves 3D party engines, but also a lot of setup time. Karma can also be used as a standalone Hydra Delegate from next year. Further in-depth information that would go beyond the scope of this article, as well as wonderful examples, can be found in Olaf’s article – already in progress!
Feather
In addition to the Clouds, the new Feather system is another highlight of Houdini 20. To provide an efficient solution to the complex production challenges of feathers, Houdini offers over 20 new Feathers nodes, many of which are GPU-accelerated and interactive as well as perfectly integrated into the existing grooming tools. Individual feathers can be created with just a few nodes or curves, a shaft and outline, and can be brought into the desired (dis)order with the existing grooming nodes such as Frizz and Clump (of which there is also a special Feather version).
In addition to the classic Guidemask Node, the new Texture Paint Mask Node can also be used to mask certain areas. To create as many different feathers as efficiently as possible, shapes can be interpolated to form new shapes. Once the individual feather (sets) have been defined, they can be quickly drawn or scatterned using the familiar grooming tools such as Guide-Groom.
New options ensure clean interpolation between different feather type areas. Otherwise, the Feather Pipeline follows the work steps of the Hair Tools exactly with a few special new nodes, such as the GPU-supported Feather-Deintersect. This node interactively prevents unwanted overlaps and also ensures a fluffier look, for example. The finished feathers can then be easily converted into polygons and resampled for simulation and animation. The feather fun is best rendered with the new Hydradelegate-independent Feather Procedural, i.e. memory-saving high-resolution only at rendertime.
Animation
The big star of H20 is undoubtedly the new APEX animation ecosystem, a direct challenge to the workflows of long-dead empires. Star text: Beta status with many good ideas, most of which are running well in initial tests and then still have to prove themselves in practice. Before we delve deeper into the topic of APEX, let’s take a brief tour of “general” improvements in terms of animation. In the animation editor, the areas of the curves can now be changed directly without having to use handles. A bit like the newer path tools in Illustrator and incredibly practical. Keyframes can now be moved via MMB without the mouse pointer having to remain directly over them.
The timeline has been given a useful companion in the form of the Animation Toolbar. Here, for example, breakdowns, tweens, easing, time offsets, noises or blending to certain frames or neighbouring keys can be set to speed up the animation processes with sliders. Finally, bookmarks can also be created and controlled with new shortcuts.
What is Apex and what has happened to KineFX?
In short, and this would have taken up most of the time writing this article, so I’ll quote SideFX at this point: “APEX, a brand new context designed to deliver an animator-friendly environment that is built using a robust procedural rigging toolset.” For animators, this really does mean a completely new, viewport-centric and interactive experience. The entire animation now happens in the new Apex Scene-Animate Node, which has no parameters other than Reset, only interactive viewport tools. And what tools!
The selection sets make it easier to select and save relevant controls, but it gets really exciting with new ideas such as locators and dynamic motion. The former allow us to set and save pivots on the go, so that we can move our mesh or character over these pivots away from the controls defined in the rig. The movement is not limited to just one mesh, but can also move everything that has been selected via the selection sets without any constraints.
And if you do need constraints, the new constraint tool allows you to create them directly in the viewport with just a few clicks (2: Driven, Driver, Done) – and remove them again or key the constraint state (On/Off). In addition, reference videos can finally be displayed in the viewport. Everything is controlled via the Animate Node tool menu. The ingenious Dynamic Motion Toolset can also be started here. Considering the original strengths of Houdini, it is only a logical consequence to integrate physical simulations directly into the animation tools.
Thankfully for all pure animators without DOP-Network and Co. the workflow is as follows: The animator sets raw keyframes and contact points for his motion paths, such as the trajectory of a ball or a jumping character, and then lets Houdini adjust the animation physically correctly, fine-tune it and bake it back as keys. Everything simulated can be adjusted at any time. The animator also has direct access to the ragdoll system, allowing him to fling his character around without keyframes.
Kine Fx and rigging
APEX does not replace KineFX, but is part of it. Skeletons, skinning and the like are implemented as before and then transferred to an APEX rig (if you want, you can also animate using a rig pose as before and combine the whole thing with APEX). The idea of APEX is basically a further development of the basic idea of KineFX to treat joints and co. as geometry. However, if rigs are too complex, this leads to performance losses, so that the APEX Graph System, which treats geometry as pure data, allows considerably better performance. For more in-depth information on procedural rigging, be sure to watch the Houdini Hive videos, especially the one by Esther Trilsch here: is.gd/h20_rigging.
Conclusion
Lots of new features and tools and still no end in sight – except for this article. If you are interested in the updates in the areas of RBD (sticky collisions!), Vellum, Flip, Muscles, Pyro, ethically correct machine learning, PDG and actually every aspect of the program (including “hidden”, i.e. undocumented changes such as the new “Create Digital Asset” dialogue), we recommend the extensive, albeit often very technical, docs at this point.
In the Content Library(www.sidefx.com/contentlibrary/) you can download sample scenes for many new features. And they are quite something – they show more advanced setups than just the new tool and take a second or two to calculate the node network due to caches that are not included when opening them. Once you have rummaged through the nodes, the examples are a real source of knowledge. As always, H20 is also available as a free non-commercial version.
Take a look and happy rendering!
