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Recent Forum Posts

How to export normal information in blend shapes? May 25, 2018, 8:54 a.m.

I'm trying to export an FBX with blendshapes for use in Unreal Engine 4, and although the vertex deformation is getting exported correctly, the corresponding normal blending is not happening - the mesh is retaining the normal information from the first frame of the animation.

I've attached a hip file which shows a very basic setup illustrating the problem. As you can see, in Houdini, the normals are being correctly blended - if you scroll from frame 0 to 100 you can see the normals changing from the first blendshape to the second one.

However, no matter how I try to export this, when I bring it into any other piece of software (Modo, Maya, UE4) there is no blending of normal information.

I've tried having the normals as vertex normals, point normals, and both at the same time, but it makes no difference.

What is the correct way to get blendshapes to carry normal information for use in other software?

HDA won't create multiple material instances March 27, 2018, 6:42 a.m.


I had to leave this part of my project for a while and I'm now just coming back to it, thanks for your response (and the fix!) and sorry for the slow response.

However, I'm having a slight issue with this now:

When I bring in the Sectioned Sphere HDA with only 1 subdivision, it assigns all the textures correctly, but if I change then subdivisions to a higher number (as I need to), then it doesn't correctly assign the “diffuse” parameter to the correct texture any more. I have attached a UE4 project for you to take a look at. You'll see that when Subdivisions is set to 1, the top row of textures run A0 to A3 and the bottom row run B0 to B3. However, setting the Subdivisions to 2 or higher, the bottom row now also runs from A0 to A3.

Looking at the HDA in Houdini, in the geometry spreadsheet it does seem like the values are correctly assigned there, so I'm not sure where the error is creeping in.

It's not an insurmountable problem for now, as I can just go through and manually change all the diffuse assignments for the lower row myself, but I'm hoping to be able to automate the creation of a sphere with a large number of tiled texture assignments in the future, where manually changing them will be annoying.

Any idea what's happening here?

How to export ROP Volume Texture with colour information? Feb. 26, 2018, 10:45 a.m.

I want to be able to export a volume texture using the ROP Volume Texture, but retaining the colour information in the volume.

But even with colour information as a Cd channel in VDB (which I can see is there in the Volume Visualization SOP), the output is always black and white.

Is there a way to retain and export the colour information?

As a possibly related question, when I try to connect up a pyro sim to the ROP Volume Texture node, it doesn't work and throws this error:

Invalid source /obj/geo1/rop_volume_texture1/vdb2
Error: ArithmeticError: Non-zero scale values required

This is from running a basic test creating a sphere and using the shelf ‘Explosion’ tool.

Any ideas?