From 6aa6626f29227dd4b998c458cee52e41ba7fdf83 Mon Sep 17 00:00:00 2001
From: Mikko Mononen <memononen@gmail.com>
Date: Wed, 7 Oct 2026 20:48:27 +0200
Subject: [PATCH] DrawList: improved handling of very small circles.

See testbed case 354.
---
 imgui_draw.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/imgui_draw.cpp b/imgui_draw.cpp
index 83ceaddc0..163022f1b 100644
--- a/imgui_draw.cpp
+++ b/imgui_draw.cpp
@@ -2761,13 +2761,14 @@ void ImDrawList::AddCircleFilled(const ImVec2& center, float radius, ImU32 col,
     if ((col & IM_COL32_A_MASK) == 0)
         return;
 
-    const float diameter = radius * 2.0f;
-    if (diameter < _FringeScale) IM_UNLIKELY
+    // Minimum radius, before the edge-AA will overlap.
+    const float min_radius = _FringeScale * 1.41421356f * 0.5f;
+    if (radius < min_radius) IM_UNLIKELY
     {
-        if (diameter < (1.0f / 255.0f) * _FringeScale)
+        if (radius < (1.0f / 255.0f) * min_radius)
             return;
-        col = ImAlphaMultiply(col, diameter * _InvFringeScale);
-        radius = _FringeScale * 0.5f;
+        col = ImAlphaMultiply(col, radius / min_radius);
+        radius = min_radius;
     }
 
     if (num_segments <= 0 && radius <= _Data->ArcFastRadiusCutoff)