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Combining volumes

Generators take an input

Every shape generator (constant, box, sphere, torus, tube, sdf, metaball, fractal) has one input, which works like the input of TouchDesigner's generator TOPs with a compositing step added. The Output page decides what happens to it:

  • Combine with Input = Set Resolution Only: the input supplies width, height, depth (with Output Resolution at Use Input) and pixel format. Its content is discarded.
  • Combine with Input = Composite and Set Resolution (the default): as above, and the generated volume is composited with the input using Operation. The generated volume is the first operand, so the default Over draws the new shape on top of the input. Swap Order reverses the operands.

Chaining generators this way builds a scene without separate composite operators:

sphere ──► box ──► torus          each one composited over the previous result

Nothing connected, the input is a single black voxel: the generator uses its own Resolution and outputs 8-bit fixed unless Pixel Format is set (see Common page).

noise differs: its first input follows the Noise TOP's RGB and Alpha combine modes, and its second input is a coordinate map. See noise.

Composers place an overlay

The two-input composers (add, subtract, multiply, difference, composite, cross, displace) work like TouchDesigner's Composite TOP in three dimensions:

  • Size picks the input that sets the output resolution. The other input is the overlay.
  • Pre-Fit Overlay scales the overlay to the output: Fill, Fit Horizontal / Vertical / Depth, Fit Best, Fit Outside or Native Resolution. Justify Horizontal / Vertical / Depth apply in Native Resolution.
  • The Transform page moves, rotates and scales the overlay about Pivot (default: the centre), in the units described in Coordinates and units.
  • Extend Overlay decides what the inputs return outside their bounds: Zero, Hold, Repeat or Mirror.

The operation itself is fixed by the operator (add adds, multiply multiplies), except in composite, where Operation chooses it. composite also takes its inputs from the Inputs sequence, one TOP and one Gain per block: the first two blocks fall back to the wired inputs when their TOP is empty, and every further block adds another input.

displace is the exception to the overlay rule: its Transform page moves the displacement map while Size is Input 2 (the default), and the source when it is Input 1.

Inputs of different resolutions

Inputs are matched by extent, not by voxel index: each output voxel samples every input at the same normalised position. A 32³ volume added to a 128³ volume is upsampled with the filtering set by Input Smoothness. The exception is a composer's Pre-Fit Overlay at Native Resolution, which keeps one overlay voxel per output voxel and uses Justify to place it.