Mitigate rare rendering bug (#7163)

* increase plane subdivision to mitigate rare rendering error

* update changelog

CHANGELOG.unreleased.md

@@ -19,6 +19,7 @@ For upgrade instructions, please check the [migration guide](MIGRATIONS.released
 - Redesigned the info tab in the right-hand sidebar to be fit the new branding and design language. [#7110](https://github.com/scalableminds/webknossos/pull/7110)
 
 ### Fixed
+- Fixed rare rendering bug at viewport edge for anisotropic datasets. [#7163](https://github.com/scalableminds/webknossos/pull/7163)
 
 ### Removed
 

frontend/javascripts/oxalis/geometries/plane.ts

@@ -12,13 +12,20 @@ import constants, {
   OrthoViewValues,
 } from "oxalis/constants";
 
-// A subdivision of 80 means that there will be 80 segments per axis
-// and thus 81 vertices per axis (i.e., the vertex shader is executed 81**2).
+// A subdivision of 100 means that there will be 100 segments per axis
+// and thus 101 vertices per axis (i.e., the vertex shader is executed 101**2).
 // In an extreme scenario, these vertices would have a distance to each other
 // of 32 voxels. Thus, each square (two triangles) would render one bucket.
-// 80**2 == 6400 buckets per plane are currently unrealistic and therefore
+// 100**2 == 10,000 buckets per plane are currently unrealistic and therefore
 // a valid upper bound.
-export const PLANE_SUBDIVISION = 80;
+// However, note that in case of anisotropic datasets, the above calculation
+// needs to be adapted a bit. For example, consider a dataset with mag 8-8-1.
+// The XZ plane could render 100 buckets along the X coordinate (as above), but
+// only ~13 buckets along the Z coordinate. This would require 1300 which is not
+// unrealistic. PLANE_SUBDIVISION values of 80 showed rare problems which is why
+// a value of 100 is now used. If this should become problematic, too, a dynamic
+// subdivision would probably be the next step.
+export const PLANE_SUBDIVISION = 100;
 
 class Plane {
   // This class is supposed to collect all the Geometries that belong to one single plane such as