Fix curve drawing crash after changing geometry nodes output.

Using geometry nodes with attributes on a curve object and changing the
output is crashing. This is because the `render_mutex` in the curve
drawing cache is cleared after changes in `curves_batch_cache_init` and
set to null. The cache isn't actually needed currently because all draw
updates are single-threaded, but the new `drw_attributes_merge` function
still tries to access it (this seems to be tolerated on Linux platforms
but crashes on Windows).

Make sure the render_mutex is always initialized after (re-)initializing
the cache.

1 files changed, 2 insertions, 1 deletions

diff --git a/source/blender/draw/intern/draw_cache_impl_curves.cc b/source/blender/draw/intern/draw_cache_impl_curves.cc
index d5f188402d6..1d3d6222f8f 100644
--- a/source/blender/draw/intern/draw_cache_impl_curves.cc
+++ b/source/blender/draw/intern/draw_cache_impl_curves.cc
@@ -75,13 +75,14 @@ static void curves_batch_cache_init(Curves &curves)
 
   if (!cache) {
     cache = MEM_cnew<CurvesBatchCache>(__func__);
-    BLI_mutex_init(&cache->render_mutex);
     curves.batch_cache = cache;
   }
   else {
     memset(cache, 0, sizeof(*cache));
   }
 
+  BLI_mutex_init(&cache->render_mutex);
+
   cache->is_dirty = false;
 }