# BlinkScript and OFX

> Running Nuke Blink kernels on the GPU, and loading OpenFX plugins.

## BlinkScript

The [BlinkScript](/docs/nodes/blinkscript) node runs Nuke Blink kernels. There is no C++ compiler involved: each kernel is translated to a GPU shader.

- Edit the kernel source in the node's panel and press **Recompile** (Ctrl+Enter). Each `param:` becomes a knob, each input image becomes a node input, in the order they are declared.
- Errors are listed with their line numbers; the node keeps its old knobs and outputs nothing until the kernel compiles.
- Kernels in .nk scripts import with their source and parameter values, and export the same way.
- Positions are in Nuke pixels (origin bottom left, y up). Edge modes `eEdgeClamped` and `eEdgeConstant` behave as in Nuke.

**Not supported:**

| Kernel feature | Why |
|---|---|
| writing to another pixel (`dst(x, y) = …`, scatter / splatting), `atomicAdd` | each output pixel is computed on its own |
| `ImageRollingKernel`, `ImageReductionKernel` | they need to run pixels in order |
| `eReadWrite` images (ParticleBlinkScript, in-place writes) | same |

In a test set of 120 real-world kernels, 104 translated and ran.

## OFX plugins

Oink loads OpenFX image plugins (the plugin standard of Nuke, Resolve, Natron and Flame). Each installed plugin becomes a node on the **OFX** button of the node toolbar and in the Tab menu. Plugins run in a separate helper process, so a crashing plugin cannot take the app down.

A GPU plugin shares the graphics card with other heavy jobs. If an AI or render job holds the card, the Viewer waits at most 5 seconds (`OPENCOMP_OFX_LEASE_WAIT_S`), then the node shows an error naming the job and passes its input through; the app never freezes. Background renders wait longer (up to 10 minutes). Frames sent to a plugin are cached in memory, up to 4 GB (`OPENCOMP_OFX_FRAME_CACHE_MB`).

Where plugins are found, and how they are saved in .nk files: [OFX plugins](/docs/reference/ofx).

## Gizmos

Gizmos are covered in [.nk import and export](/docs/nuke-users/nk-import#how-nodes-are-translated): put `.gizmo` files in `~/.nuke`, `~/.opencomp/gizmos` or a folder on `NUKE_PATH` and they appear in the Tab menu.


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Sources: opencomp_core/nodes/filter/blinkscript.py, opencomp_core/blink/translate.py, opencomp_core/blink/nk.py, opencomp_core/ofx/__init__.py, opencomp_core/nodes/ofx/ofx_nodes.py