VDBRead

3Dv1app

Overview

Reads a .vdb volume cache (smoke, clouds, fire from FX or a bought pack) into the scene as a standard UsdVol prim. Loads off-thread — the box draws dim while streaming, bright when ready. Rendering the volume itself lands with the volume pass; today you get the placed, pickable bounding box.

How to

How-to

Set file (a smoke.####.vdb sequence resolves per frame) and the grid.
Loads off-thread; the panel names the resolved frame and turns amber when it is missing.
A VolumeShade sets the look.

Inputs

Input	What it takes
in	the image this node works on

Outputs

Output	Type
out	Scene

Parameters

Parameter	Type	Default	What it does
tx	Float	0.0	Translate X — position along the world X axis, metres.
ty	Float	0.0	Translate Y — position along the world Y axis (up), metres.
tz	Float	0.0	Translate Z — position along the world Z axis, metres. The camera looks down −Z.
rx	Float	0.0	Rotate around X, degrees.
ry	Float	0.0	Rotate around Y (turntable), degrees.
rz	Float	0.0	Rotate around Z (roll), degrees.
sx	Float	1.0	Scale along X. 1 = unchanged.
sy	Float	1.0	Scale along Y.
sz	Float	1.0	Scale along Z.
file	Text		The .vdb on disk. Big caches stream in the background — the viewport never waits on this file.
grid	Text	density	Which grid (field) to read — 'density' in most smoke/cloud caches, 'temperature' for fire. Empty = the first float grid in the file.
emission_grid	Text		A companion grid of the same file that scales the emission (Houdini's `flame` or `heat`), the way its Pyro shader splits fire. Empty = the density scales it.
temperature_grid	Text		A companion grid a blackbody VolumeShade colours by (`temperature`). Empty = none.
units	Choice	voxel	What one unit of density means. `world` integrates per metre along the ray, as Houdini's renderers do; `voxel` per index voxel, the look older comps were made with. New nodes are created in `world`. `voxelworld`
first	Int	0	The clip's frame range on disk.
last	Int	0	The clip's frame range on disk.
before	Choice	black	What plays outside the range: hold the end frame, loop, bounce, or black. `holdloopbounceblack`
after	Choice	black	What plays outside the range: hold the end frame, loop, bounce, or black. `holdloopbounceblack`
frame_mode	Choice	none	Where the cache sits in time, the Read node's meaning: `none` plays the file's own numbers; `start_at` slides the sequence so its first frame lands on `start_at`; `offset` adds `frame_offset`. `nonestart_atoffset`
start_at	Int	1	The shot frame the sequence's first frame lands on when `frame_mode` is `start_at`.
frame_offset	Int	0	Frames added to the shot frame to find the file when `frame_mode` is `offset`.
disabled	Bool	false	Bypass: the node passes its first input through untouched (D in the graph). The knobs keep their values for when it comes back.
label	Text		A note shown under the node in the graph — what this node is FOR. Never affects the render or the cache.
hide_input	Bool	false	Draw the node without its input wire — a tidy graph for a node whose source is obvious (a Dot, a viewer tap).