animatrix

VEX Select Edges By Primitive Attribute SOP

Selects edges using a primitive attribute that have different values for each primitive of the edge.

It's much faster than the default Group from Attribute Boundary SOP. It shows once again the power of half edges in VEX.

https://www.dropbox.com/s/cb33kinmo42b26l/SelectEdgesByPrimitiveAttribute_SOP_Animatrix.otl?dl=1

2021-12-05 09:15:15 +0000 UTC View Post

Frosted Glass COP

Distorts an image as if it's viewed through a frosted glass.

Same trick can be applied to volumes, point cloud look ups, texture look ups, etc.

https://www.dropbox.com/s/294xzxe88hn59md/FrostedGlass_COP_Animatrix.otl?dl=1

Supercharged H19

I have recently updated Supercharged to work natively with Houdini 19. It's now more robust thanks to the built-in viewport Qt handle added by SideFX. Due to this, this version is not backwards compatible.

I was on the H19 beta so I tested the new Qt handle and it allowed the overlay network editor to update and track viewport changes a lot better. That's why this is an important update.

It should also work better on some Linux distros.

There will be some more upcoming chang...

Native SceneViewer Qt Handle in H19

Finally SESI added the ability to directly acquire the Qt handle that holds the SceneViewer. This is one of the non-advertised features but is quite useful for Qt developers. Especially since my Supercharged enhancements heavily rely on this to work properly.

https://www.sidefx.com/docs/houdini/hom/hou/SceneViewer.html

The overall benefit from having this natively is you no longer ...

UV Visualize SOP

Applies an image file as a textured shader to a surface to visualize UVs.

It has options to override the embedded UV tile image file as well as the ability to selectively toggle diffuse and reflection elements and/or specify a reflection map.

You can also specify the UV attribute to use, apply scaling to the textures, and toggle the use of lighting for the geometry.

OpenGL customization in Houdini is pretty slim so there isn't a whole lot of things that you can do with this ...

Limit Surface Sampling - Creating Isolines on the Subdivision Limit Surface

There is a useful modeling concept that's available in many 3d apps including Houdini where you see the original geometry projected onto the subdivision limit surface that allows you to see the flow of the geometry without cluttering the view with the newly added geometric detail.  And that's what we will create in this lesson.

Limit Surface Sampling - Pre-Generating a Point Cloud on the Subdivision Limit Surface

When we are talking about creating a lot of points, we can not avoid pre-generating them for maximum performance. It might not always be applicable but when it is, the performance gains can be quite significant.

Limit Surface Sampling - Scattering & Generating Points on the Subdivision Limit Surface

If you have access to the subdivision limit surface by patch IDs and the patch UVs, then surely you can scatter points on the limit subdivision limit surface just like you scatter points on a polygonal surface.  And this is exactly what we are gonna do in this chapter.

Limit Surface Sampling - Moving Points to the Subdivision Limit Surface

There is a very practical use of the limit surface to figure out where a point is on the subdivision limit surface.

Imagine a character head like the one we were using, and you add a lot of detail to it, just like what we did before using adaptive subdivision.

That sounds all good in action, but what we are missing is the future projection of the same geometry, by additional subdivision, either as a post operation before exporting out the geometry, or as a render time operation. 2021-09-02 13:01:01 +0000 UTC View Post

Limit Surface Sampling - Introduction & OpenSubdiv Patches

Releasing time exclusive Limit Surface Sampling chapter from Pragmatic VEX: Volume 1 course.

To generate interpolating surfaces for other subdivision schemes we need a method of determining the position and the normal at a set of points on the limit surface. Because the surface is the result of repeated application of a subdivision step, we can analyze the behavior of a small neighborhood of points as they converge to the limit surface in order to determine the surface properties at the...

1 year anniversary

Celebrating 1 year anniversary of Pragmatic VEX: Volume 1!

Since its inception it has been a huge success among the high end VFX studios and artists alike.

And for that I am hugely grateful!

Therefore it will be on a discounted sale for a week until August 20 12 PM PST.

Also I will post several time exclusive videos from the course here for the patrons. Hope you will find them useful in your own work :)

Enjoy!

Bricker SOP [Parallel]

Divide the polygon into a mesh-like series of polygons. This aids in surface deformation operations.

The advantage of this operator over the standard Divide SOP is that this operator runs in parallel utilizing all available CPU cores to speed up the performance significantly.

I have used this operator on multiple large scale destruction movies and it reduced cook times for adding extra detail significantly.

Just compiling the network is not enough though, as the 3d slicing g...

Divergence VOP

Computes the divergence of a vector field.

In vector calculus, divergence is a vector operator that operates on a vector field, producing a ...

SOP Updates

Adaptive Subdivide SOP

Updated internals to use Select Unshared Edges SOP

Proximity SOP & Neighbour SOP

Added the ability to output weights array attribute for generic convolution implementations using these.

Select Poly Loop SOP

Updated internals to use Group Promote SOP instead of Select Boundary Edges SOP.

2021-06-26 11:05:32 +0000 UTC View Post

Temporally Stable Oriented Bounding Box (OBB) [Extract Transform SOP]

Before I posted an example of this using the Rigid Transform SOP. The same result can now be obtained using the Extract Transform SOP in Houdini 18.5, which now supports the extraction of non-uniform scales.

It's useful to know how to do this using the standard operators. Many studios restrict the use of external tools so you might find yourself in this situation.

In the gif the outer bbox is from the Extract Transform SOP. As you can see both operators perfectly match.

2021-06-12 09:33:02 +0000 UTC View Post

Time Bound SOP

Accumulates an axis aligned bounding box in time with the option to make it oriented bounding box with optional padding.

Very useful in computing simulation domain of a geometry.

https://www.dropbox.com/s/mt6du3zkm8cj1ss/TimeBound_SOP_Animatrix.otl?dl=1

VEX Delete Primitives By Size SOP

Deletes primitives by area or length.

Extremely useful for optimizing for geometry for simulations such as RBD. Can exclude small pieces that are simply not visible or insignificant.

You can exclude them from fracturing also. Then merge it back using the second output which is the inverted result of the operator.

https://www.dropbox.com/s/06htjylyalleqt...

Poly Curves From Edges SOP

Creates polygonal curves from an edge group where point order of the curves will be in the same direction as the point order of each edge selection and closed edge selections will be created as closed polygons unless specified otherwise.

Some tricks about serializing edges and creating them in VEX.

https://www.dropbox.com/s/17objbi3zg2r94q/PolyCurvesFromEdges_SO...

Motion Blur Trail SOP

Takes an input and makes a trail of each point over time, and connects the trails in different ways accounting for camera motion. This results in long streaky motion blur effects baked onto the points.

Uses the improved TimeBlend SOP that can blend between subframes for higher precision.

https://www.dropbox.com/s/witlonnj5kqw3sd/MotionBlurTrail_SOP_Animat...

VEX Limit Surface Sample SOP and VEX Path Deform SOP [Updates]

Limit Surface Sample SOP: Added support for vertex attributes

Path Deform SOP: Replaced Curve Frame nodes inside with Orientation Along Curve nodes, and promoted Extrapolate End Tangents option.

https://www.dropbox.com/s/2mr3j1l8mwdu1n7/LimitSurfaceSample_SOP_Animatrix.otl?dl=1

2021-03-01 13:53:36 +0000 UTC View Post

VEX Delete Overlapping Polygons SOP

Efficiently deletes overlapping polygons that share the same points.

Depending on the geometry this operator can be 100s of times faster than the PolyDoctor SOP's equivalent functionality.

https://www.dropbox.com/s/902k7i7dg0av6th/DeleteOverlappingPolygons_SOP_Animatrix.otl?dl=1

VEX Geometry SOP

Creates an offline copy of a geometry without any dependency.

It's like the Stash SOP but using VEX to recreate the input geometry. Can be passed around in textual form or keep the geometry "embedded" within a scene.

https://www.dropbox.com/s/gj8ercv5m5mxqdh/Geometry_SOP_Animatrix.otl?dl=1

Generic pcfilter VEX function

In SOPs pcfilter is the only function that still makes pcopen relevant. It's a function that smooth interpolates attribute values of the points found by the point cloud look up. 

This is an implementation of the same function that you can use for anything given an array of point indices, distances and an attribute name. This particular version is for vector attributes, but you can easily adapt it to any other floating attribute type.

2021-01-07 08:39:22 +0000 UTC View Post

VEX Subdivide SOP [Update]

Subdivide SOP is updated to use the new hscript expression vertexgrouplist that's added in Houdini 18.5, rather than having to use VEX to store the same vertex group list, which is more expensive.

I filed this RFE while I was working on Pragmatic VEX: Volume 1, so SESI added it in 18.5. The course has also been updated to mention this with the release of Houdini 18.5.

htt...

Curve Gradient SOP [Update]

Brand new implementation that uses Edge Transport SOP internally.

Edge Transport SOP is faster than Find Shortest Path SOP in this case, and makes the HDA internals a lot simpler.

There are many ways to do this in Houdini but each of these methods still miss some features to have a smooth workflow, and as such they are not enough by themselves. 

That's why Curve Gradient SOP still proves to be useful in the latest production workflows.

2020-12-09 12:11:43 +0000 UTC View Post

VEX Delete Points By Proximity SOP

Deletes points iteratively using proximity.

Very useful when deleting stray particles in FLIP, grain simulations.

https://www.dropbox.com/s/bzmqvxhoedvi8xo/DeletePointsByProximity_SOP_Animatrix.otl?dl=1

Python Slide Edges SOP

Slides edges along the surface.

The same operation can easily be implemented in VEX using half edges. This was implemented before VEX had half edges.

Edges in Houdini are very expensive computationally, but half edges provide a reasonable alternative for these kinds of operations.

https://www.dropbox.com/s/b71smfvc4wzhaa0/SlideEdges_SOP_Animatrix.otl?dl=1

VEX Convex Hull 2D SOP

Creates the 2D convex hull of the input geometry.

https://www.dropbox.com/s/9b66pt36q5sg48d/ConvexHull2D_SOP_Animatrix.otl?dl=1

https://www.dropbox.com/s/izpm6lkjvb96wpq/PCA_SOP_Animatrix.otl?dl=1

Spherize COP

Transforms an image into a perfect sphere.

Custom multisample anti-aliasing (MSAA) as well as bilinear and full filtering options.

https://www.dropbox.com/s/egpir9c79ssmyv4/Spherize_COP_Animatrix.otl?dl=1

Integrated Advanced Code Editor (Visual Studio Code)

I started to implement an integrated advanced code editor based on the same editor that powers Visual Studio Code.

It practically has all the features one can ask for in a professional code editor.

There are still a few key things missing like better default color themes, etc, but it already has a lot of features that are simply not present in the default code editor in Houdini. 

Patreon members will receive a free license once it's released.