Polygon buffer also shrinks when it can (#958)

almarklein · kushalkolar · web-flow · commit 9abe236407b1 · 2025-12-03T22:23:14.000-05:00
* Polygon buffer also shrinks when it can.

* fix for zero

* remove unused import

---------

Co-authored-by: kushalkolar &lt;kushalkolar@gmail.com&gt;
diff --git a/examples/guis/sine_cosine_funcs.py b/examples/guis/sine_cosine_funcs.py
@@ -9,7 +9,6 @@
 # test_example = false
 # sphinx_gallery_pygfx_docs = 'screenshot'
 
-import glfw
 import numpy as np
 import fastplotlib as fpl
 from fastplotlib.ui import EdgeWindow
diff --git a/fastplotlib/graphics/features/_selection_features.py b/fastplotlib/graphics/features/_selection_features.py
@@ -416,12 +416,14 @@ def set_value(self, selector, value: Sequence[tuple[float]]):
 
         geometry = selector.geometry
 
-        # Need larger buffer?
-        if len(value) > geometry.positions.nitems:
-            arr = np.zeros((geometry.positions.nitems * 2, 3), np.float32)
+        # Need larger (or smaller) buffer? Scale up/down with factors of 2.
+        need_position_size = 2 ** int(np.ceil(np.log2(max(8, len(value)))))
+        if need_position_size != geometry.positions.nitems:
+            arr = np.zeros((need_position_size, 3), np.float32)
             geometry.positions = gfx.Buffer(arr)
-        if len(indices) > geometry.indices.nitems:
-            arr = np.zeros((geometry.indices.nitems * 2, 3), np.int32)
+        need_indices_size = 2 ** int(np.ceil(np.log2(max(8, len(indices)))))
+        if need_indices_size != geometry.indices.nitems:
+            arr = np.zeros((need_indices_size, 3), np.int32)
             geometry.indices = gfx.Buffer(arr)
 
         geometry.positions.data[: len(value)] = value
