SIGHT TOOLS / BLK
BLK Optimization Guide
Reduce the number of drawing objects in an existing War Thunder sight without redrawing it.
What the tool does
What is actually counted
A War Thunder sight is a BLK file: a list of parameters and drawing primitives. Only the drawable records consume the budget — line, quad/drawQuad, circle and text records inside the documented drawing sections. A technical block that merely happens to be named line is not a drawing line and is never counted.
What optimization changes
It rewrites the geometry so the game draws the same picture with fewer objects. Duplicated geometry is removed, collinear line segments and adjacent quads are merged, zero-length geometry is dropped, and the contours of brushes, polylines, curves, fills, shapes and hatching are then simplified at increasing tolerances. Every candidate has to reduce the object count, leave protected records untouched and stay inside the permitted visual difference; fills and hatching must additionally preserve contour topology, so a simplification cannot close a narrow opening or cut through a hole. Each candidate is compared against the original file rather than against the previous step, so several individually small changes cannot accumulate into a visible one.
What optimization does not do
It does not raise, bypass or remove War Thunder's own limits. The game still enforces them on load. Optimization only moves your file further below the limit it already had to respect.
Uploading the file
What you can upload
A War Thunder sight in .blk format — and nothing else: the tool reads the game format, not JSON and not images. The size limit is 500 KiB for a standard account and 3 MiB with Premium; a larger file is refused before any work is done. Export the BLK from the Sight Converter or from the Sight Draw Editor if you only have it as a JSON project.
Use Smooth Edge
This single checkbox decides which limit applies to the file. It is written into the export as useSmoothEdge:b=yes or useSmoothEdge:b=no, and it selects the object budget the file is measured against: 2650 objects with smoothing on, 8000 with it off. Turn it off only if you are prepared for small gaps between neighbouring lines to become more visible.
Result and statistics
Reading the numbers
The result reports the object count before and after, the reduction, the visual difference the optimizer measured, the limit that applied to this file and the state of that limit. The state is the honest summary of the count: within the smooth-edge budget, over the smooth-edge budget, or over the hard budget. Above 8000 objects the file is over the hard limit and export is blocked; between the applicable limit and 8000 it is a warning, not a refusal.
| Setting | Limit | What happens |
|---|---|---|
| Use Smooth Edge on | 2650 | above it, a warning |
| Use Smooth Edge off | 8000 | above it, export is blocked |
| Recommended sight size | 2500 | the panel starts warning at 2200 |
What is never simplified
Text, circles, and any element carrying protected game fields — move, moveRadial, radialAngle, or BLK parameter names the editor does not manage — are left exactly as they were. They are reported as skipped, so you can see which parts of the sight the optimizer deliberately did not touch.
When there was no reduction
The tool does not hand back an "optimized" file when no pass reduced the object count: in that case the original document is returned and the message that no significant reduction was achieved is shown. That is an honest result, not an error. It happens most often with sights built mostly from text, circles and short lines that have nothing to merge.
Using the result
Open it in the Sight Draw Editor
The optimized document can be handed straight to the Sight Draw Editor, where you can inspect the surviving geometry and export the file again. If you would rather keep control of the file, download the BLK and open it there with OPEN BLK, or download the JSON and open it with OPEN JSON.
Download BLK and JSON
Download the JSON to keep the optimized drawing as an editable Hub Thunder project, and the BLK to install the sight in the game. They are the same drawing: the BLK is generated from the JSON. Keep the JSON as the editable master, because comments and formatting are not carried into the BLK. Install the file using the installation guide.
Quota
The daily allowance
Optimizations are counted in one shared daily pool. The Sight Draw Editor, Image To Sight and BLK Optimization all draw from the same counter, so the tools compete for one allowance. A standard account gets 10 optimizations per day; Premium is unlimited. The counter resets at 00:00 UTC. A run that fails is released and does not consume the allowance.