Volumes

A T3D volume is an ordinary TOP whose texture type is 3D Texture: width × height × depth voxels of RGBA. T3D operators connect with TOP wires, so a volume can pass through anything in TouchDesigner that handles 3D textures. The family registers the native null, select, in, out, cache and feedback TOPs for that reason: they carry volumes unchanged and can be placed from the T3D menu.

The channels have no fixed meaning. Each operator documents what it reads and writes; the render operators treat the input as coloured density (see their pages).

Getting volumes in and out

From	To	Operator
2D image: as a plane, extruded by a height image, or stacked frame by frame over time	volume	top_to
SOP or POP geometry	volume	geo_to
Points: positions and colours as TOPs, or a POP	volume	point_cloud
volume	2D image: all slices, or one slice	to_top
volume	points scattered where the volume passes a threshold	sprinkle
volume	particles moved through the volume	advect
volume	rendered image	volume, voltrace, surface

Groups

The operators are grouped the way the T3D menu shows them:

• Generator: create a volume, optionally composited over the input.
• Filter: one volume in, one volume out, voxel by voxel or by neighbourhood.
• Composer: two or more volumes in, one out.
• Renderer: draw a volume into a Render TOP's scene.
• Other: simulation, particles, conversion to 2D, and the native TOPs.

The operator index lists all of them.

Cooking

T3D operators cook only when an input or parameter changes, like any TOP. Measured with nothing changing, an unchanged network recooks none of its GLSL passes, so a static volume costs nothing per frame. Each operator page gives its GPU time when it does recook.