System Information
Operating system: Win 10 pro
Graphics card: RTX 2080
Blender Version
Broken: 2.80 66684bdff30f
Short description of error
When using the spin modifier and the merge vertices option the mesh disappears.
This began happening 7-3 and onward.
Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).
Divide a plane,
Delete half,
Add spin modifier
Click merge vertices
@Clément Foucault (fclem), I know it's not your area, but I'm pretty sure that this problem came from your commit rB2866c742080d
Here a possible fix:
diff --git a/source/blender/modifiers/intern/MOD_screw.c b/source/blender/modifiers/intern/MOD_screw.c index 3c84bb7ae15..5ffa38f71f2 100644 --- a/source/blender/modifiers/intern/MOD_screw.c +++ b/source/blender/modifiers/intern/MOD_screw.c @@ -132,6 +132,9 @@ static Mesh *mesh_remove_doubles_on_axis(Mesh *result, tot_doubles += 1; copy_v3_v3(mvert_new[i].co, axis_co); } + else { + mvert_new[i].flag &= ~ME_VERT_TMP_TAG; + } } if (tot_doubles != 0) {