Geo COMP

The Geometry COMP (Geo COMP) is the fundamental container that places 3D geometry into the scene. It wraps a SOP network (your mesh/points) and adds the properties needed to render it: transform, material, instancing, and render settings.

You can think of the Geo COMP as the “actor” on stage — it holds a mesh (from SOPs) and tells the Render TOP how, where, and how many times to draw it.

Key Pages

Xform (Transform) Page

Controls where the geometry sits in 3D space:

Parameter	Description
Translate (tx, ty, tz)	Position in world space
Rotate (rx, ry, rz)	Euler angles in degrees
Scale (sx, sy, sz)	Uniform or non-uniform scale
Pivot	Point around which rotation and scale is applied
Order	Transformation and rotation order — matters for complex rigs

Render Page

Parameter	Description
Render	On/Off — whether this geometry is picked up by Render TOPs
Display	On/Off — whether it shows in viewport previews
Material	Path to a MAT operator for the surface shader
Shadow Caster / Receiver	Enable shadow casting/receiving

Instance Page

This is where instancing lives — see Instancing for a full guide.

Parameter	Description
Instancing	Turn ON to duplicate this geometry many times
Instance CHOP/DAT	The CHOP or DAT providing per-instance transform data
Translate (tx/ty/tz)	Which channels from the Instance CHOP drive position
Rotate / Scale	Similarly mapped channel names

Wiring Geometry In

The Geo COMP takes SOP operators as its input:

Box SOP → [input 0 of Geo COMP]

Alternatively, you can build the SOP network inside the Geo COMP:

• Double-click the Geo COMP to go inside it.
• You’ll find a default torus1 SOP and out1 SOP.
• Replace the torus with your own geometry. The out1 SOP is what gets displayed.

You can also reference an external SOP without wiring it in, by using a SOP To operator or a CHOP Reference inside the network.

Typical Rendering Setup

Box SOP
  └→ Geo COMP
       ├── Material: op('/project1/phong1')    ← MAT reference in the Render page
       └── Xform: tx = op('lfo1')['chan1']     ← expression on tx

Camera COMP
Light COMP
Render TOP
  └── [auto-discovers Geo COMP, Camera, Light at same level]
  └→ Null TOP (OUT_RENDER)

Animating the Transform

You can drive any Xform parameter with a CHOP reference or expression:

• Rotate Y continuously: absTime.seconds * 30 (30°/sec)
• From LFO: op('lfo1')['chan1'] * 5
• CHOP Export: Drag a CHOP channel onto ty and choose Export

Material Assignment

The Geo COMP does not have its own surface look — you must assign a MAT:

1. Go to the Render page of the Geo COMP.
2. Set the Material field to the path of your MAT node (e.g. /project1/phong1).
3. Alternatively, you can assign materials per primitive inside the SOP network using an Material SOP.

Common Gotchas

• Nothing renders → check the Render flag is ON, a Material is assigned, and the Camera is pointing at it.
• Geometry is inside-out → flip normals using a Facet SOP (Normals → Reverse).
• Moving the Geo COMP doesn’t move the mesh → make sure you’re editing the Geo COMP’s Xform, not the SOP inside it.
• Instancing shows only one copy → the Instance CHOP must have more than one sample; check the CHOP channel count with the Info popup (I).

Related Nodes

• (y-) SOP — geometry source
• Render TOP — renders the scene to a texture
• (y-) MAT — surface shaders
• Instancing — duplicating geometry efficiently

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(y-) Next Chapter: DATs

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