maya-compositing

maya-compositing (Pipeline stage)

Builds the shading/utility node network that combines already-rendered imagery inside Maya, so a comp can be reviewed or rendered without leaving the scene. It is the companion to render_setup.plan_comp_outputs, which decides where those images land on disk.

Typical flow

1. create_image_reader — one per image sequence. Set use_frame_extension=True for name.####.exr sequences, and frame_offset when the render starts at a non-zero frame.
2. create_layer_stack — an empty layeredTexture to stack into.
3. add_comp_layer — connect each reader, choosing blend_mode and opacity.
4. list_comp_layers — verify order, modes and opacity before rendering.
5. merge_comp_layers — shortcut for two sources: blend gives a uniform mix via blender, the other operations stack with the matching blend mode.
6. create_comp_node + connect_comp_nodes — insert reverse, multiplyDivide, luminance, clamp or setRange for keys and grades.

Verified Maya behaviours

Three things are easy to get wrong and invisible under a mock (all verified on Maya 2025):

• layeredTexture.inputs reports size == 0 via getAttr(s=True) before the first connection, and listConnections(..., plugs=True) on the array returns the source plugs (f1.outColor), not the destination elements. Neither reveals an index, so the layer index comes from probing each element - and that also lets a removed layer's slot be reused.
• grade and colorCorrect exist as node types but createNode returns an unknown node in a batch session, so they are not offered.
• file.imageName does not exist; only fileTextureName is settable.

Input plugs differ per node type: multiplyDivide uses input1/input2, plusMinusAverage uses input3D, and reverse/clamp use a plain input.

Scope

This skill builds comp networks. It does not render or plan paths:

• where renders land → render_setup.plan_comp_outputs (maya-render-setup)
• render layers, AOVs → maya-render-setup
• rendering frames → maya-render / maya-render-farm