camera projection with houdini

Houdini camera projection is as simple as creating a "UV TEXTURE" node and plugging it into the geo you're projecting onto.
In this node, select "Perspective from Camera", from the Texture Type dropdown menu.
You could name the UV Attribute something other than the default of "uv" if you are creating some alternate uv sets.
In the Camera dialog box, specify the camera node. Eg. /obj/cam1 & usually the attribute class for the uv's will be set to vertex.

Now, whatever material you apply to it will use these uv's. (or maybe a different set if you specify within the shader network!) eg. uv2.

size of array, VEX snippet

i@size=len(i[]@nameOfArray);

the [] is actually [   ].

activating particles

to have particles come alive, mid sim (or indeed, to have them stop mid sim) you just need to trigger the "stopped" attribute in your pop network.

blurring vdbs

float dist = xyzdist(1,@P);

float distremap = fit(dist,ch("near"),ch("far"),0,1);

f@density *= distremap;


This gives a vdb a falloff based on how close it is to the original object's surface.
Stick the VDB into a volume visualisation and then plug that into input 0
Put the original geo into input 2.

Now you can "blur"

group centroids

group centre/centroid - intstead of blasting out groups and using $CEX etc, you can just use $GCX, $GCY, $GCZ in your transform pivots.

Selection expand

To expand - any - selection like in Maya... do your selecting then press SHIFT G (to grow) or SHIFT S (to shrink)

seperated AOVs eg(z depth at 32 bit)

Half precision and 32 bit for z depth 

16 bit half precision but utility passes in 32 bit. 

- on your AOV, tick Separate File
- set the filepath to the same location as your beauty render but with the name of the pass suffixed, e.g. for the Z depth it might be: _$HIP/../../render/$OS/$HIPNAME/`$OS`_Z.$F4.exr_
- set Precision to 'Float 32 bit'