DrawList: Fixed divide-by-zero or glitches with Radius/Rounding values close to zero. (#5249, #5293, #3491)

Amend 8ed34af6f8

docs/CHANGELOG.txt

@@ -85,8 +85,9 @@ Other Changes:
   always lead to menu closure. Fixes using items that are not MenuItem() or BeginItem() at the root
   level of a popup with a child menu opened.
 - Stack Tool: Added option to copy item path to clipboard. (#4631)
-- Drawlist: Fixed PathArcTo() emitting terminating vertices too close to arc vertices. (#4993) [@thedmd]
+- DrawList: Fixed PathArcTo() emitting terminating vertices too close to arc vertices. (#4993) [@thedmd]
 - DrawList: Fixed texture-based anti-aliasing path with RGBA textures (#5132, #3245) [@cfillion]
+- DrawList: Fixed divide-by-zero or glitches with Radius/Rounding values close to zero. (#5249, #5293, #3491)
 - Debug: Added DebugTextEncoding() function to facilitate diagnosing issues when not sure about whether
   you have a UTF-8 text encoding issue or a font loading issue. [@LaMarche05, @ocornut]
 - Metrics: Added a "UTF-8 Encoding Viewer" section using the aforementioned DebugTextEncoding() function.

imgui.h

@@ -65,7 +65,7 @@ Index of this file:
 // Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals. Work in progress versions typically starts at XYY99 then bounce up to XYY00, XYY01 etc. when release tagging happens)
 #define IMGUI_VERSION               "1.88 WIP"
-#define IMGUI_VERSION_NUM           18720
+#define IMGUI_VERSION_NUM           18721
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 #define IMGUI_HAS_TABLE
 

imgui_draw.cpp

@@ -393,7 +393,7 @@ void ImDrawListSharedData::SetCircleTessellationMaxError(float max_error)
     for (int i = 0; i < IM_ARRAYSIZE(CircleSegmentCounts); i++)
     {
         const float radius = (float)i;
-        CircleSegmentCounts[i] = (ImU8)((i > 0) ? IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC(radius, CircleSegmentMaxError) : 0);
+        CircleSegmentCounts[i] = (ImU8)((i > 0) ? IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC(radius, CircleSegmentMaxError) : IM_DRAWLIST_ARCFAST_SAMPLE_MAX);
     }
     ArcFastRadiusCutoff = IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC_R(IM_DRAWLIST_ARCFAST_SAMPLE_MAX, CircleSegmentMaxError);
 }
@@ -1058,7 +1058,7 @@ void ImDrawList::AddConvexPolyFilled(const ImVec2* points, const int points_coun
 
 void ImDrawList::_PathArcToFastEx(const ImVec2& center, float radius, int a_min_sample, int a_max_sample, int a_step)
 {
-    if (radius <= 0.0f)
+    if (radius < 0.5f)
     {
         _Path.push_back(center);
         return;
@@ -1150,7 +1150,7 @@ void ImDrawList::_PathArcToFastEx(const ImVec2& center, float radius, int a_min_
 
 void ImDrawList::_PathArcToN(const ImVec2& center, float radius, float a_min, float a_max, int num_segments)
 {
-    if (radius <= 0.0f)
+    if (radius < 0.5f)
     {
         _Path.push_back(center);
         return;
@@ -1169,7 +1169,7 @@ void ImDrawList::_PathArcToN(const ImVec2& center, float radius, float a_min, fl
 // 0: East, 3: South, 6: West, 9: North, 12: East
 void ImDrawList::PathArcToFast(const ImVec2& center, float radius, int a_min_of_12, int a_max_of_12)
 {
-    if (radius <= 0.0f)
+    if (radius < 0.5f)
     {
         _Path.push_back(center);
         return;
@@ -1179,7 +1179,7 @@ void ImDrawList::PathArcToFast(const ImVec2& center, float radius, int a_min_of_
 
 void ImDrawList::PathArcTo(const ImVec2& center, float radius, float a_min, float a_max, int num_segments)
 {
-    if (radius <= 0.0f)
+    if (radius < 0.5f)
     {
         _Path.push_back(center);
         return;
@@ -1360,7 +1360,7 @@ void ImDrawList::PathRect(const ImVec2& a, const ImVec2& b, float rounding, ImDr
     rounding = ImMin(rounding, ImFabs(b.x - a.x) * ( ((flags & ImDrawFlags_RoundCornersTop)  == ImDrawFlags_RoundCornersTop)  || ((flags & ImDrawFlags_RoundCornersBottom) == ImDrawFlags_RoundCornersBottom) ? 0.5f : 1.0f ) - 1.0f);
     rounding = ImMin(rounding, ImFabs(b.y - a.y) * ( ((flags & ImDrawFlags_RoundCornersLeft) == ImDrawFlags_RoundCornersLeft) || ((flags & ImDrawFlags_RoundCornersRight)  == ImDrawFlags_RoundCornersRight)  ? 0.5f : 1.0f ) - 1.0f);
 
-    if (rounding <= 0.0f || (flags & ImDrawFlags_RoundCornersMask_) == ImDrawFlags_RoundCornersNone)
+    if (rounding < 0.5f || (flags & ImDrawFlags_RoundCornersMask_) == ImDrawFlags_RoundCornersNone)
     {
         PathLineTo(a);
         PathLineTo(ImVec2(b.x, a.y));
@@ -1406,7 +1406,7 @@ void ImDrawList::AddRectFilled(const ImVec2& p_min, const ImVec2& p_max, ImU32 c
 {
     if ((col & IM_COL32_A_MASK) == 0)
         return;
-    if (rounding <= 0.0f || (flags & ImDrawFlags_RoundCornersMask_) == ImDrawFlags_RoundCornersNone)
+    if (rounding < 0.5f || (flags & ImDrawFlags_RoundCornersMask_) == ImDrawFlags_RoundCornersNone)
     {
         PrimReserve(6, 4);
         PrimRect(p_min, p_max, col);
@@ -1646,7 +1646,7 @@ void ImDrawList::AddImageRounded(ImTextureID user_texture_id, const ImVec2& p_mi
         return;
 
     flags = FixRectCornerFlags(flags);
-    if (rounding <= 0.0f || (flags & ImDrawFlags_RoundCornersMask_) == ImDrawFlags_RoundCornersNone)
+    if (rounding < 0.5f || (flags & ImDrawFlags_RoundCornersMask_) == ImDrawFlags_RoundCornersNone)
     {
         AddImage(user_texture_id, p_min, p_max, uv_min, uv_max, col);
         return;

imgui_internal.h

@@ -694,7 +694,6 @@ struct ImChunkStream
 //
 // Rendering circles with an odd number of segments, while mathematically correct will produce
 // asymmetrical results on the raster grid. Therefore we're rounding N to next even number (7->8, 8->8, 9->10 etc.)
-//
 #define IM_ROUNDUP_TO_EVEN(_V)                                  ((((_V) + 1) / 2) * 2)
 #define IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_MIN                     4
 #define IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_MAX                     512