Texture-based thick lines: Minor tweaks and rename toward merging in master. Changes to allow changing AA_SIZE (disable texture path).

docs/CHANGELOG.txt

@@ -35,6 +35,15 @@ HOW TO UPDATE?
  VERSION 1.78 WIP (In Progress)
 -----------------------------------------------------------------------
 
+Other Changes:
+
+- ImDrawList: Thick anti-aliased strokes (> 1.0f) with integer thickness now use a texture-based 
+  path, reducing the amount of vertices/indices and CPU/GPU usage. (#3245) [@Shironekoben]
+  - This change will facilitate the wider use of thick borders in future style changes. 
+  - Requires an extra bit of texture space (~64x64 by default), relies on GPU bilinear filtering.
+  - Clear io.AntiAliasedLinesUseTex = false; to disable rendering using this method.
+  - Clear ImFontAtlasFlags_NoBakedLines in ImFontAtlas::Flags to disable baking data in texture.
+
 
 -----------------------------------------------------------------------
  VERSION 1.77 (Released 2020-06-29)

imgui.cpp

@@ -935,7 +935,7 @@ ImGuiStyle::ImGuiStyle()
     DisplaySafeAreaPadding  = ImVec2(3,3);      // If you cannot see the edge of your screen (e.g. on a TV) increase the safe area padding. Covers popups/tooltips as well regular windows.
     MouseCursorScale        = 1.0f;             // Scale software rendered mouse cursor (when io.MouseDrawCursor is enabled). May be removed later.
     AntiAliasedLines        = true;             // Enable anti-aliased lines/borders. Disable if you are really tight on CPU/GPU.
-    AntiAliasedLinesUseTex  = true;             // Enable anti-aliased lines/borders using textures where possible. Requires back-end to render with bilinear filtering.
+    AntiAliasedLinesUseTex  = true;             // Enable anti-aliased lines/borders using textures where possible. Require back-end to render with bilinear filtering.
     AntiAliasedFill         = true;             // Enable anti-aliased filled shapes (rounded rectangles, circles, etc.).
     CurveTessellationTol    = 1.25f;            // Tessellation tolerance when using PathBezierCurveTo() without a specific number of segments. Decrease for highly tessellated curves (higher quality, more polygons), increase to reduce quality.
     CircleSegmentMaxError   = 1.60f;            // Maximum error (in pixels) allowed when using AddCircle()/AddCircleFilled() or drawing rounded corner rectangles with no explicit segment count specified. Decrease for higher quality but more geometry.
@@ -3689,7 +3689,7 @@ void ImGui::NewFrame()
     g.DrawListSharedData.InitialFlags = ImDrawListFlags_None;
     if (g.Style.AntiAliasedLines)
         g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedLines;
-    if (g.Style.AntiAliasedLinesUseTex && !(g.Font->ContainerAtlas->Flags & ImFontAtlasFlags_NoAntiAliasedLines))
+    if (g.Style.AntiAliasedLinesUseTex && !(g.Font->ContainerAtlas->Flags & ImFontAtlasFlags_NoBakedLines))
         g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedLinesUseTex;
     if (g.Style.AntiAliasedFill)
         g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedFill;
@@ -6161,7 +6161,7 @@ void ImGui::SetCurrentFont(ImFont* font)
 
     ImFontAtlas* atlas = g.Font->ContainerAtlas;
     g.DrawListSharedData.TexUvWhitePixel = atlas->TexUvWhitePixel;
-    g.DrawListSharedData.TexUvAALines = atlas->TexUvAALines;
+    g.DrawListSharedData.TexUvLines = atlas->TexUvLines;
     g.DrawListSharedData.Font = g.Font;
     g.DrawListSharedData.FontSize = g.FontSize;
 }

imgui.h

@@ -60,7 +60,7 @@ 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               "1.78 WIP"
-#define IMGUI_VERSION_NUM           17702
+#define IMGUI_VERSION_NUM           17703
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 
 // Define attributes of all API symbols declarations (e.g. for DLL under Windows)
@@ -1438,9 +1438,9 @@ struct ImGuiStyle
     ImVec2      DisplayWindowPadding;       // Window position are clamped to be visible within the display area by at least this amount. Only applies to regular windows.
     ImVec2      DisplaySafeAreaPadding;     // If you cannot see the edges of your screen (e.g. on a TV) increase the safe area padding. Apply to popups/tooltips as well regular windows. NB: Prefer configuring your TV sets correctly!
     float       MouseCursorScale;           // Scale software rendered mouse cursor (when io.MouseDrawCursor is enabled). May be removed later.
-    bool        AntiAliasedLines;           // Enable anti-aliased lines/borders. Disable if you are really tight on CPU/GPU.
-    bool        AntiAliasedLinesUseTex;     // Enable anti-aliased lines/borders using textures where possible. Requires back-end to render with bilinear filtering.
-    bool        AntiAliasedFill;            // Enable anti-aliased edges around filled shapes (rounded rectangles, circles, etc.). Disable if you are really tight on CPU/GPU.
+    bool        AntiAliasedLines;           // Enable anti-aliased lines/borders. Disable if you are really tight on CPU/GPU. Latched at the beginning of the frame (copied to ImDrawList).
+    bool        AntiAliasedLinesUseTex;     // Enable anti-aliased lines/borders using textures where possible. Require back-end to render with bilinear filtering. Latched at the beginning of the frame (copied to ImDrawList).
+    bool        AntiAliasedFill;            // Enable anti-aliased edges around filled shapes (rounded rectangles, circles, etc.). Disable if you are really tight on CPU/GPU. Latched at the beginning of the frame (copied to ImDrawList).
     float       CurveTessellationTol;       // Tessellation tolerance when using PathBezierCurveTo() without a specific number of segments. Decrease for highly tessellated curves (higher quality, more polygons), increase to reduce quality.
     float       CircleSegmentMaxError;      // Maximum error (in pixels) allowed when using AddCircle()/AddCircleFilled() or drawing rounded corner rectangles with no explicit segment count specified. Decrease for higher quality but more geometry.
     ImVec4      Colors[ImGuiCol_COUNT];
@@ -1897,9 +1897,9 @@ struct ImColor
 // Hold a series of drawing commands. The user provides a renderer for ImDrawData which essentially contains an array of ImDrawList.
 //-----------------------------------------------------------------------------
 
-// The maximum line width to bake anti-aliased textures for. Build atlas with ImFontAtlasFlags_NoAALines to disable baking.
-#ifndef IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX
-#define IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX      (63)
+// The maximum line width to bake anti-aliased textures for. Build atlas with ImFontAtlasFlags_NoBakedLines to disable baking.
+#ifndef IM_DRAWLIST_TEX_LINES_WIDTH_MAX
+#define IM_DRAWLIST_TEX_LINES_WIDTH_MAX     (63)
 #endif
 
 // ImDrawCallback: Draw callbacks for advanced uses [configurable type: override in imconfig.h]
@@ -1998,14 +1998,14 @@ enum ImDrawCornerFlags_
     ImDrawCornerFlags_All       = 0xF     // In your function calls you may use ~0 (= all bits sets) instead of ImDrawCornerFlags_All, as a convenience
 };
 
-#define IMGUI_HAS_TEXLINES      1
-
+// Flags for ImDrawList. Those are set automatically by ImGui:: functions from ImGuiIO settings, and generally not manipulated directly.
+// It is however possible to temporarily alter flags between calls to ImDrawList:: functions.
 enum ImDrawListFlags_
 {
     ImDrawListFlags_None                    = 0,
     ImDrawListFlags_AntiAliasedLines        = 1 << 0,  // Enable anti-aliased lines/borders (*2 the number of triangles for 1.0f wide line or lines thin enough to be drawn using textures, otherwise *3 the number of triangles)
-    ImDrawListFlags_AntiAliasedFill         = 1 << 1,  // Enable anti-aliased edge around filled shapes (rounded rectangles, circles).
-    ImDrawListFlags_AntiAliasedLinesUseTex  = 1 << 2,  // Should anti-aliased lines be drawn using textures where possible?
+    ImDrawListFlags_AntiAliasedLinesUseTex  = 1 << 1,  // Enable anti-aliased lines/borders using textures when possible. Require back-end to render with bilinear filtering.
+    ImDrawListFlags_AntiAliasedFill         = 1 << 2,  // Enable anti-aliased edge around filled shapes (rounded rectangles, circles).
     ImDrawListFlags_AllowVtxOffset          = 1 << 3   // Can emit 'VtxOffset > 0' to allow large meshes. Set when 'ImGuiBackendFlags_RendererHasVtxOffset' is enabled.
 };
 
@@ -2226,7 +2226,7 @@ enum ImFontAtlasFlags_
     ImFontAtlasFlags_None               = 0,
     ImFontAtlasFlags_NoPowerOfTwoHeight = 1 << 0,   // Don't round the height to next power of two
     ImFontAtlasFlags_NoMouseCursors     = 1 << 1,   // Don't build software mouse cursors into the atlas (save a little texture memory)
-    ImFontAtlasFlags_NoAntiAliasedLines = 1 << 2    // Don't build anti-aliased line textures into the atlas (save a little texture memory). They will be rendered using polygons (a little bit more expensive)
+    ImFontAtlasFlags_NoBakedLines       = 1 << 2    // Don't build thick line textures into the atlas (save a little texture memory). The AntiAliasedLinesUseTex features uses them, otherwise they will be rendered using polygons (more expensive for CPU/GPU).
 };
 
 // Load and rasterize multiple TTF/OTF fonts into a same texture. The font atlas will build a single texture holding:
@@ -2327,11 +2327,11 @@ struct ImFontAtlas
     ImVector<ImFont*>           Fonts;              // Hold all the fonts returned by AddFont*. Fonts[0] is the default font upon calling ImGui::NewFrame(), use ImGui::PushFont()/PopFont() to change the current font.
     ImVector<ImFontAtlasCustomRect> CustomRects;    // Rectangles for packing custom texture data into the atlas.
     ImVector<ImFontConfig>      ConfigData;         // Configuration data
-    ImVec4                      TexUvAALines[IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX + 1];   // UVs for anti-aliased line textures
+    ImVec4                      TexUvLines[IM_DRAWLIST_TEX_LINES_WIDTH_MAX + 1];  // UVs for baked anti-aliased lines
 
     // [Internal] Packing data
     int                         PackIdMouseCursors; // Custom texture rectangle ID for white pixel and mouse cursors
-    int                         PackIdAALines;      // Custom texture rectangle ID for anti-aliased lines
+    int                         PackIdLines;        // Custom texture rectangle ID for baked anti-aliased lines
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     typedef ImFontAtlasCustomRect    CustomRect;         // OBSOLETED in 1.72+

imgui_demo.cpp

@@ -3832,7 +3832,7 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
             ImGui::Checkbox("Anti-aliased lines", &style.AntiAliasedLines);
             ImGui::SameLine(); HelpMarker("When disabling anti-aliasing lines, you'll probably want to disable borders in your style as well.");
             ImGui::Checkbox("Anti-aliased lines use texture", &style.AntiAliasedLinesUseTex);
-            ImGui::SameLine(); HelpMarker("Faster lines using texture data. Requires texture to use bilinear sampling (not nearest).");
+            ImGui::SameLine(); HelpMarker("Faster lines using texture data. Require back-end to render with bilinear filtering (not point/nearest filtering).");
             ImGui::Checkbox("Anti-aliased fill", &style.AntiAliasedFill);
             ImGui::PushItemWidth(100);
             ImGui::DragFloat("Curve Tessellation Tolerance", &style.CurveTessellationTol, 0.02f, 0.10f, 10.0f, "%.2f");

imgui_draw.cpp

@@ -358,7 +358,7 @@ ImDrawListSharedData::ImDrawListSharedData()
         ArcFastVtx[i] = ImVec2(ImCos(a), ImSin(a));
     }
     memset(CircleSegmentCounts, 0, sizeof(CircleSegmentCounts)); // This will be set by SetCircleSegmentMaxError()
-    TexUvAALines = NULL;
+    TexUvLines = NULL;
 }
 
 void ImDrawListSharedData::SetCircleSegmentMaxError(float max_error)
@@ -681,11 +681,13 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
         const int integer_thickness = (int)thickness;
         const float fractional_thickness = thickness - integer_thickness;
 
-        // 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)
-        const bool use_texture = (Flags & ImDrawListFlags_AntiAliasedLinesUseTex) && (integer_thickness < IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX) && (fractional_thickness >= -0.00001f) && (fractional_thickness <= 0.00001f);
+        // 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);
 
-        // We should never hit this, because NewFrame() doesn't set ImDrawListFlags_AntiAliasedLinesUseTexData unless ImFontAtlasFlags_NoAALines is off
-        IM_ASSERT_PARANOID((!use_texture) || (!(_Data->Font->ContainerAtlas->Flags & ImFontAtlasFlags_NoAALines)));
+        // 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));
 
         const int idx_count = use_texture ? (count * 6) : (thick_line ? count * 18 : count * 12);
         const int vtx_count = use_texture ? (points_count * 2) : (thick_line ? points_count * 4 : points_count * 3);
@@ -693,7 +695,7 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
 
         // Temporary buffer
         // The first <points_count> items are normals at each line point, then after that there are either 2 or 4 temp points for each line point
-        ImVec2* temp_normals = (ImVec2*)alloca(points_count * ((thick_line && !use_texture) ? 5 : 3) * sizeof(ImVec2)); //-V630
+        ImVec2* temp_normals = (ImVec2*)alloca(points_count * ((use_texture || !thick_line) ? 3 : 5) * sizeof(ImVec2)); //-V630
         ImVec2* temp_points = temp_normals + points_count;
 
         // Calculate normals (tangents) for each line segment
@@ -717,7 +719,7 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
 
             // The width of the geometry we need to draw - this is essentially <thickness> pixels for the line itself, plus one pixel for AA
             // We don't use AA_SIZE here because the +1 is tied to the generated texture and so alternate values won't work without changes to that code
-            const float half_draw_size = use_texture ? ((thickness * 0.5f) + 1) : 1.0f;
+            const float half_draw_size = use_texture ? ((thickness * 0.5f) + 1) : AA_SIZE;
 
             // If line is not closed, the first and last points need to be generated differently as there are no normals to blend
             if (!closed)
@@ -775,10 +777,10 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
             if (use_texture)
             {
                 // If we're using textures we only need to emit the left/right edge vertices
-                ImVec4 tex_uvs = _Data->TexUvAALines[integer_thickness];
+                ImVec4 tex_uvs = _Data->TexUvLines[integer_thickness];
                 if (fractional_thickness != 0.0f)
                 {
-                    const ImVec4 tex_uvs_1 = _Data->TexUvAALines[integer_thickness + 1];
+                    const ImVec4 tex_uvs_1 = _Data->TexUvLines[integer_thickness + 1];
                     tex_uvs.x = tex_uvs.x + (tex_uvs_1.x - tex_uvs.x) * fractional_thickness; // inlined ImLerp()
                     tex_uvs.y = tex_uvs.y + (tex_uvs_1.y - tex_uvs.y) * fractional_thickness;
                     tex_uvs.z = tex_uvs.z + (tex_uvs_1.z - tex_uvs.z) * fractional_thickness;
@@ -1719,7 +1721,7 @@ ImFontAtlas::ImFontAtlas()
     TexWidth = TexHeight = 0;
     TexUvScale = ImVec2(0.0f, 0.0f);
     TexUvWhitePixel = ImVec2(0.0f, 0.0f);
-    PackIdMouseCursors = PackIdAALines = -1;
+    PackIdMouseCursors = PackIdLines = -1;
 }
 
 ImFontAtlas::~ImFontAtlas()
@@ -1747,7 +1749,7 @@ void    ImFontAtlas::ClearInputData()
         }
     ConfigData.clear();
     CustomRects.clear();
-    PackIdMouseCursors = PackIdAALines = -1;
+    PackIdMouseCursors = PackIdLines = -1;
 }
 
 void    ImFontAtlas::ClearTexData()
@@ -2387,27 +2389,15 @@ static void ImFontAtlasBuildRenderDefaultTexData(ImFontAtlas* atlas)
     atlas->TexUvWhitePixel = ImVec2((r->X + 0.5f) * atlas->TexUvScale.x, (r->Y + 0.5f) * atlas->TexUvScale.y);
 }
 
-static void ImFontAtlasBuildRegisterAALineCustomRects(ImFontAtlas* atlas)
+static void ImFontAtlasBuildRenderLinesTexData(ImFontAtlas* atlas)
 {
-    if (atlas->Flags & ImFontAtlasFlags_NoAntiAliasedLines)
+    if (atlas->Flags & ImFontAtlasFlags_NoBakedLines)
         return;
 
-    // The +2 here is to give space for the end caps, whilst height +1 is to accommodate the fact we have a zero-width row
-    atlas->PackIdAALines = atlas->AddCustomRectRegular(IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX + 2, IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX + 1);
-}
-
-static void ImFontAtlasBuildRenderAALinesTexData(ImFontAtlas* atlas)
-{
-    IM_ASSERT(atlas->TexPixelsAlpha8 != NULL);
-    if (atlas->Flags & ImFontAtlasFlags_NoAntiAliasedLines)
-        return;
-
-    ImFontAtlasCustomRect* r = atlas->GetCustomRectByIndex(atlas->PackIdAALines);
-    IM_ASSERT(r->IsPacked());
-
     // This generates a triangular shape in the texture, with the various line widths stacked on top of each other to allow interpolation between them
-    const int w = atlas->TexWidth;
-    for (unsigned int n = 0; n < IM_DRAWLIST_TEX_AA_LINES_WIDTH_MAX + 1; n++) // +1 because of the zero-width row
+    ImFontAtlasCustomRect* r = atlas->GetCustomRectByIndex(atlas->PackIdLines);
+    IM_ASSERT(r->IsPacked());
+    for (unsigned int n = 0; n < IM_DRAWLIST_TEX_LINES_WIDTH_MAX + 1; n++) // +1 because of the zero-width row
     {
         // Each line consists of at least two empty pixels at the ends, with a line of solid pixels in the middle
         unsigned int y = n;
@@ -2415,30 +2405,18 @@ static void ImFontAtlasBuildRenderAALinesTexData(ImFontAtlas* atlas)
         unsigned int pad_left = (r->Width - line_width) / 2;
         unsigned int pad_right = r->Width - (pad_left + line_width);
 
-        // Make sure we're inside the texture bounds before we start writing pixels
-        IM_ASSERT_PARANOID(pad_left + line_width + pad_right == r.Width);
-        IM_ASSERT_PARANOID(y < r.Height);
-
         // Write each slice
-        unsigned char* write_ptr = &atlas->TexPixelsAlpha8[r->X + ((r->Y + y) * w)];
-        for (unsigned int x = 0; x < pad_left; x++)
-            *(write_ptr++) = 0;
-        for (unsigned int x = 0; x < line_width; x++)
-            *(write_ptr++) = 0xFF;
-        for (unsigned int x = 0; x < pad_right; x++)
-            *(write_ptr++) = 0;
+        IM_ASSERT(pad_left + line_width + pad_right == r->Width && y < r->Height); // Make sure we're inside the texture bounds before we start writing pixels
+        unsigned char* write_ptr = &atlas->TexPixelsAlpha8[r->X + ((r->Y + y) * atlas->TexWidth)];
+        memset(write_ptr, 0x00, pad_left);
+        memset(write_ptr + pad_left, 0xFF, line_width);
+        memset(write_ptr + pad_left + line_width, 0x00, pad_right);
 
         // Calculate UVs for this line
-        ImFontAtlasCustomRect line_rect = *r;
-        line_rect.X += (unsigned short)(pad_left - 1);
-        line_rect.Y += (unsigned short)y;
-        line_rect.Width = (unsigned short)(line_width + 2);
-        line_rect.Height = 1;
-
-        ImVec2 uv0, uv1;
-        atlas->CalcCustomRectUV(&line_rect, &uv0, &uv1);
+        ImVec2 uv0 = ImVec2((float)(r->X + pad_left - 1), (float)(r->Y + y)) * atlas->TexUvScale;
+        ImVec2 uv1 = ImVec2((float)(r->X + pad_left + line_width + 1), (float)(r->Y + y + 1)) * atlas->TexUvScale;
         float half_v = (uv0.y + uv1.y) * 0.5f; // Calculate a constant V in the middle of the row to avoid sampling artifacts
-        atlas->TexUvAALines[n] = ImVec4(uv0.x, half_v, uv1.x, half_v);
+        atlas->TexUvLines[n] = ImVec4(uv0.x, half_v, uv1.x, half_v);
     }
 }
 
@@ -2454,15 +2432,22 @@ void ImFontAtlasBuildInit(ImFontAtlas* atlas)
             atlas->PackIdMouseCursors = atlas->AddCustomRectRegular(2, 2);
     }
 
-    ImFontAtlasBuildRegisterAALineCustomRects(atlas);
+    // Register texture region for thick lines
+    // The +2 here is to give space for the end caps, whilst height +1 is to accommodate the fact we have a zero-width row
+    if (atlas->PackIdLines < 0)
+    {
+        if (!(atlas->Flags & ImFontAtlasFlags_NoBakedLines))
+            atlas->PackIdLines = atlas->AddCustomRectRegular(IM_DRAWLIST_TEX_LINES_WIDTH_MAX + 2, IM_DRAWLIST_TEX_LINES_WIDTH_MAX + 1);
+    }
 }
 
 // This is called/shared by both the stb_truetype and the FreeType builder.
 void ImFontAtlasBuildFinish(ImFontAtlas* atlas)
 {
     // Render into our custom data blocks
+    IM_ASSERT(atlas->TexPixelsAlpha8 != NULL);
     ImFontAtlasBuildRenderDefaultTexData(atlas);
-    ImFontAtlasBuildRenderAALinesTexData(atlas);
+    ImFontAtlasBuildRenderLinesTexData(atlas);
 
     // Register custom rectangle glyphs
     for (int i = 0; i < atlas->CustomRects.Size; i++)

imgui_internal.h

@@ -544,8 +544,7 @@ struct IMGUI_API ImDrawListSharedData
     // [Internal] Lookup tables
     ImVec2          ArcFastVtx[12 * IM_DRAWLIST_ARCFAST_TESSELLATION_MULTIPLIER];  // FIXME: Bake rounded corners fill/borders in atlas
     ImU8            CircleSegmentCounts[64];    // Precomputed segment count for given radius (array index + 1) before we calculate it dynamically (to avoid calculation overhead)
-
-    const ImVec4*   TexUvAALines;               // UV of anti-aliased lines in the atlas
+    const ImVec4*   TexUvLines;                 // UV of anti-aliased lines in the atlas
 
     ImDrawListSharedData();
     void SetCircleSegmentMaxError(float max_error);