SoftBox

Soft shadow area light for Nuke 17 ScanlineRender2

By Marten Blumen

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ScanlineRender2's built-in lights only cast hard shadows. SoftBox produces smooth, physically plausible penumbras by emitting a grid of sub-lights spread across a rectangular light surface — the same technique used in production VFX before stochastic shadow sampling became standard.

Features

• Soft shadows via multi-light grid (1 to 64+ sub-lights)
• Artist-friendly — single Shadow Samples knob controls quality vs speed
• Energy conserving — total illumination stays constant regardless of sample count
• Full transform — translate, rotate, scale via standard Axis_knob
• Viewport wireframe — orange rectangle with direction arrow
• USD native — creates standard DiskLightPrims on the scene graph

Installation

From Release

1. Download AreaLight.dll from Releases
2. Copy AreaLight.dll and menu.py to ~/.nuke/
3. Restart Nuke 17
4. Find AreaLight under 3D > Lights in the toolbar

Build From Source

Requires Visual Studio 2022 and CMake 3.20+.

git clone https://github.com/YOUR_USERNAME/SoftBox.git
cd SoftBox
cmake -S . -B build --preset vs2022
cmake --build build --config Release

The plugin is built to build/plugin/AreaLight.dll. To install:

cmake --install build

This copies AreaLight.dll and menu.py to ~/.nuke/.

If Nuke is installed in a non-standard location:

cmake -S . -B build --preset vs2022 -DNUKE_DIR="D:/Apps/Nuke17.0v1"

Usage

1. Create an AreaLight node and connect it to your scene
2. Set Width and Height for the light surface size
3. Adjust Intensity, Exposure, and Color
4. Set Shadow Samples to control shadow softness:

Shadow Samples	Grid	Quality	Use Case
1	—	Hard shadow	Look-dev, fast iteration
4	2×2	Basic penumbra	Previz
16	4×4	Smooth	Recommended default
64	8×8	Very smooth	Final renders, close-ups

5. Connect to ScanlineRender2 and render

How It Works

ScanlineRender2's DiskLight shader shoots a single shadow ray to the light centre, producing a hard edge. SoftBox creates N DiskLightPrims arranged in a grid across the rectangular surface. Each sub-light gets intensity / N so total illumination is conserved. The overlapping hard shadows from different positions blend into a smooth penumbra gradient.

Shadow softness is determined by the light's physical size (Width × Height). Shadow Samples controls the smoothness of the gradient, not the penumbra width.

Tips

• Shadow softness = light size. Bigger light = wider penumbra
• Shadow Samples = smoothness. More samples = less banding
• Keep at 1 during look-dev, crank up for finals
• Render time scales linearly with sample count

Project Structure

SoftBox/
├── UsdAreaLightOp.cpp    # Plugin implementation
├── UsdAreaLightOp.h      # Plugin header
├── CMakeLists.txt        # Build configuration
├── CMakePresets.json     # VS2022 preset
├── menu.py               # Nuke menu installer
├── LICENSE               # MIT license
└── README.md             # This file

Requirements

• Nuke 17.0 or later
• Windows x64
• ScanlineRender2

License

MIT — see LICENSE for details.