ImDrawList: Internals: Add ability to scale anti-alias fringe. This enable users to keep geometry sharp while scaling vertex buffer content.

imgui.h

@@ -2333,6 +2333,7 @@ struct ImDrawList
     ImVector<ImVec2>        _Path;              // [Internal] current path building
     ImDrawCmdHeader         _CmdHeader;         // [Internal] template of active commands. Fields should match those of CmdBuffer.back().
     ImDrawListSplitter      _Splitter;          // [Internal] for channels api (note: prefer using your own persistent instance of ImDrawListSplitter!)
+    float                   _FringeScale;       // [Internal] anti-alias fringe is scaled by this value, this helps to keep things sharp while zooming at vertex buffer content
 
     // If you want to create ImDrawList instances, pass them ImGui::GetDrawListSharedData() or create and use your own ImDrawListSharedData (so you can use ImDrawList without ImGui)
     ImDrawList(const ImDrawListSharedData* shared_data) { memset(this, 0, sizeof(*this)); _Data = shared_data; }

imgui_draw.cpp

@@ -405,6 +405,7 @@ void ImDrawList::_ResetForNewFrame()
     _Path.resize(0);
     _Splitter.Clear();
     CmdBuffer.push_back(ImDrawCmd());
+    _FringeScale = 1.0f;
 }
 
 void ImDrawList::_ClearFreeMemory()
@@ -680,12 +681,12 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
 
     const ImVec2 opaque_uv = _Data->TexUvWhitePixel;
     const int count = closed ? points_count : points_count - 1; // The number of line segments we need to draw
-    const bool thick_line = (thickness > 1.0f);
+    const bool thick_line = (thickness > _FringeScale);
 
     if (Flags & ImDrawListFlags_AntiAliasedLines)
     {
         // Anti-aliased stroke
-        const float AA_SIZE = 1.0f;
+        const float AA_SIZE = _FringeScale;
         const ImU32 col_trans = col & ~IM_COL32_A_MASK;
 
         // Thicknesses <1.0 should behave like thickness 1.0
@@ -696,7 +697,7 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
         // Do we want to draw this line using a texture?
         // - For now, only draw integer-width lines using textures to avoid issues with the way scaling occurs, could be improved.
         // - If AA_SIZE is not 1.0f we cannot use the texture path.
-        const bool use_texture = (Flags & ImDrawListFlags_AntiAliasedLinesUseTex) && (integer_thickness < IM_DRAWLIST_TEX_LINES_WIDTH_MAX) && (fractional_thickness <= 0.00001f);
+        const bool use_texture = (Flags & ImDrawListFlags_AntiAliasedLinesUseTex) && (integer_thickness < IM_DRAWLIST_TEX_LINES_WIDTH_MAX) && (fractional_thickness <= 0.00001f) && (AA_SIZE == 1.0f);
 
         // We should never hit this, because NewFrame() doesn't set ImDrawListFlags_AntiAliasedLinesUseTex unless ImFontAtlasFlags_NoBakedLines is off
         IM_ASSERT_PARANOID(!use_texture || !(_Data->Font->ContainerAtlas->Flags & ImFontAtlasFlags_NoBakedLines));
@@ -938,7 +939,7 @@ void ImDrawList::AddConvexPolyFilled(const ImVec2* points, const int points_coun
     if (Flags & ImDrawListFlags_AntiAliasedFill)
     {
         // Anti-aliased Fill
-        const float AA_SIZE = 1.0f;
+        const float AA_SIZE = _FringeScale;
         const ImU32 col_trans = col & ~IM_COL32_A_MASK;
         const int idx_count = (points_count - 2)*3 + points_count * 6;
         const int vtx_count = (points_count * 2);