"Vector Curl" on Volume Builder?

justinleduc

Hey guys,

This is a quick one: I can't seem to be able to add a "Vector Curl" filter to my Volume Builder. No matter my settings, I always get a "Volume Filter" that is set to "Smooth".

Here is the relevant portion of my code:

# Create Null container
nullContainer = c4d.BaseObject(c4d.Onull)
nullContainer.SetName('Vectors Direction')
doc.InsertObject(nullContainer)

# Create volume builder object
volumeBuilder = c4d.BaseObject(c4d.Ovolumebuilder)

# Volume builder settings
volumeBuilder[c4d.ID_BASELIST_NAME] = "Volume Builder 01"
volumeBuilder[c4d.ID_VOLUMEBUILDER_VOLUMETYPE] = 2
volumeBuilder[c4d.ID_VOLUMEBUILDER_GRID_SIZE] = 0.5

# Volume filter
volumeBuilderFilterCurl = c4d.BaseObject(c4d.Ovolumefilter)

# Volume filter settings
volumeBuilderFilterCurl[c4d.ID_VOLUMEFILTER_VECTOR_FILTER_TYPE] = 1

volumeBuilder.InsertUnder(nullContainer)

clonedActiveObject.InsertUnder(volumeBuilder)

volumeBuilderFilterCurl.InsertUnder(volumeBuilder)

Any help/insight would be greatly appreciated.

Thank you!

Justin

i_mazlov

Hi Justin,

Thank you for reaching out to us and providing your question with the explanatory code snippet, highly appreciated!

Regarding your question, there are two points to mention:

Firstly, you are using constant 1 for the c4d.ID_VOLUMEFILTER_VECTOR_FILTER_TYPE parameter, which targets "normalize" type rather than "curl" type (which corresponds to value 0). I suggest using the literal constants instead, e.g. change the line in your code from

volumeBuilderFilterCurl[c4d.ID_VOLUMEFILTER_VECTOR_FILTER_TYPE] = 1

to

volumeBuilderFilterCurl[c4d.ID_VOLUMEFILTER_VECTOR_FILTER_TYPE] = c4d.ID_VOLUMEFILTER_VECTOR_FILTER_TYPE_CURL

You can find the full parameter list on the page: volumes/description/ovolumefilter.h

Secondly, you forgot to set the volume filter type to vector. Just add the following line after initializing the filter object:

volumeBuilderFilterCurl[c4d.ID_VOLUMEFILTER_VOLUME_TYPE] = c4d.ID_VOLUMEFILTER_VOLUME_TYPE_VECTOR

This parameter is not referenced in python docs (sometimes it can happen), so it is worth double checking in the C++ documentation: ovolumefilter.h File Reference

Cheers,
Ilia

justinleduc

Hey @i_mazlov, thank you so much for your incredibly helpful and thorough reply. This is exactly what I was looking for.

Thanks again! I really appreciate it!