P2STMap

A Nuke plugin that converts position passes (P) to STMap coordinates using camera matrices — more efficient than chaining three C44Matrix nodes.

Inspired by Ivan Busquets's C44Matrix.

What It Does

P2STMap takes a world position pass and a camera, then applies the full projection pipeline in a single node:

1. Inverse Transform — World space → Camera space
2. Projection (with W-divide) — Camera space → NDC
3. Format (with W-divide) — NDC → Pixel coordinates
4. Normalize — Pixel coordinates → ST coordinates (0-1)

The output is a proper STMap that can be used with Nuke's STMap node for reprojection workflows.

Inputs

Input	Description
P	Position pass (world coordinates in RGB, typically with A=1)
cam	Camera node for projection matrices

Output

Channel	Value
R	U coordinate (normalized X)
G	V coordinate (normalized Y)
B	Z depth
A	W component

Compatibility

Platform	Architecture
Windows	x64
Linux	x64
macOS	ARM64/x64

Pre-built binaries available in COMPILED/

Installation

1. Copy the plugin from COMPILED/ for your platform to your .nuke directory or plugin path
2. Add the path to Nuke via init.py:

   nuke.pluginAddPath('/path/to/P2STMap')

3. Restart Nuke — the node appears under Transform/P2STMap

Usage

1. Connect your position pass to the P input
2. Connect your camera to the cam input
3. The output is an STMap ready for use

Typical workflow:

[Position Pass] → [P2STMap] → [STMap] → [Reproject/Retime]
                      ↑
                  [Camera]

Why Use This?

Previously, converting a position pass to STMap required chaining multiple C44Matrix nodes with different settings:

• C44Matrix (inverse transform, no w_divide)
• C44Matrix (projection, with w_divide)
• C44Matrix (format, with w_divide)
• Expression (normalize by format dimensions)

P2STMap combines all of this into a single, optimized node.

Building from Source

Platform-specific CMake files are provided:

• CMakeLists_WIN.txt
• CMakeLists_LINUX.txt
• CMakeLists_MAC.txt

See building_step_by_step.txt for detailed instructions.

Requirements

• CMake
• Nuke NDK (included with Nuke installation)
• C++ compiler (MSVC on Windows, GCC on Linux, Clang on macOS)

Related

• C44Matrix — General 4x4 matrix transformation plugin (with added Axis support)

Author

Peter Mercell