New Polyline rendering

imgui.cpp

@@ -1309,6 +1309,7 @@ ImGuiStyle::ImGuiStyle()
     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. Require backend to render with bilinear filtering (NOT point/nearest filtering).
     AntiAliasedFill             = true;             // Enable anti-aliased filled shapes (rounded rectangles, circles, etc.).
+    LegacyPolyline              = false;            // Enable fallback to legacy AddPolyline() to trade feature and precission for speed.
     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.
     CircleTessellationMaxError  = 0.30f;            // 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.
 
@@ -4774,8 +4775,11 @@ static void SetupDrawListSharedData()
         g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedLinesUseTex;
     if (g.Style.AntiAliasedFill)
         g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedFill;
+    if (g.Style.LegacyPolyline)
+        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_LegacyPolyline;
     if (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset)
         g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AllowVtxOffset;
+    g.DrawListSharedData.InitialFringeScale = g.IO.DisplayFramebufferScale.x ? 1.0f / g.IO.DisplayFramebufferScale.x : 1.0f;
 }
 
 void ImGui::NewFrame()

imgui.h

@@ -163,6 +163,7 @@ struct ImDrawData;                  // All draw command lists required to render
 struct ImDrawList;                  // A single draw command list (generally one per window, conceptually you may see this as a dynamic "mesh" builder)
 struct ImDrawListSharedData;        // Data shared among multiple draw lists (typically owned by parent ImGui context, but you may create one yourself)
 struct ImDrawListSplitter;          // Helper to split a draw list into different layers which can be drawn into out of order, then flattened back.
+struct ImDrawListPolyline;          // Helper to draw a polyline
 struct ImDrawVert;                  // A single vertex (pos + uv + col = 20 bytes by default. Override layout with IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT)
 struct ImFont;                      // Runtime data for a single font within a parent ImFontAtlas
 struct ImFontAtlas;                 // Runtime data for multiple fonts, bake multiple fonts into a single texture, TTF/OTF font loader
@@ -2178,6 +2179,7 @@ struct ImGuiStyle
     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 backend to render with bilinear filtering (NOT point/nearest 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).
+    bool        LegacyPolyline;             // Enable fallback to legacy AddPolyline() to trade feature and precission for speed.
     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       CircleTessellationMaxError; // 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];
@@ -2998,6 +3000,18 @@ enum ImDrawFlags_
     ImDrawFlags_RoundCornersAll             = ImDrawFlags_RoundCornersTopLeft | ImDrawFlags_RoundCornersTopRight | ImDrawFlags_RoundCornersBottomLeft | ImDrawFlags_RoundCornersBottomRight,
     ImDrawFlags_RoundCornersDefault_        = ImDrawFlags_RoundCornersAll, // Default to ALL corners if none of the _RoundCornersXX flags are specified.
     ImDrawFlags_RoundCornersMask_           = ImDrawFlags_RoundCornersAll | ImDrawFlags_RoundCornersNone,
+    ImDrawFlags_JoinMiter                   = 1 << 9, // PathStroke(), AddPolyline(): join vertices with a sharp (i.e. not rounded) corner. When miter length exceed miter limit join is converted to Bevel
+    ImDrawFlags_JoinMiterClip               = 2 << 9, // PathStroke(), AddPolyline(): as above but clipped at the miter limit (reduces visual artifacts at junctions)
+    ImDrawFlags_JoinBevel                   = 3 << 9, // PathStroke(), AddPolyline(): join vertices with a beveled corner (i.e. not rounded)
+    ImDrawFlags_JoinRound                   = 4 << 9, // PathStroke(), AddPolyline(): join vertices with a rounded corner
+    ImDrawFlags_JoinDefault_                = ImDrawFlags_JoinMiter, // Default to Miter join
+    ImDrawFlags_JoinMask_                   = 7 << 9,
+    ImDrawFlags_CapNone                     = 1 << 12, // PathStroke(), AddPolyline(): do not render end caps
+    ImDrawFlags_CapButt                     = 2 << 12, // PathStroke(), AddPolyline(): render end caps as a rectangle for anti-aliased polyline, otherwise same as CapNone for aliased polyline
+    ImDrawFlags_CapSquare                   = 3 << 12, // PathStroke(), AddPolyline(): render end caps as a square
+    ImDrawFlags_CapRound                    = 4 << 12, // PathStroke(), AddPolyline(): render end caps as a semi-circle
+    ImDrawFlags_CapDefault_                 = ImDrawFlags_CapNone, // Default to no cap
+    ImDrawFlags_CapMask_                    = 7 << 12,
 };
 
 // Flags for ImDrawList instance. Those are set automatically by ImGui:: functions from ImGuiIO settings, and generally not manipulated directly.
@@ -3009,6 +3023,7 @@ enum ImDrawListFlags_
     ImDrawListFlags_AntiAliasedLinesUseTex  = 1 << 1,  // Enable anti-aliased lines/borders using textures when possible. Require backend to render with bilinear filtering (NOT point/nearest 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.
+    ImDrawListFlags_LegacyPolyline          = 1 << 4,  // (Legacy) For AddPolyline() to trade features and precission for a bit of extra performance.
 };
 
 // Draw command list
@@ -3081,8 +3096,9 @@ struct ImDrawList
 
     // General polygon
     // - Only simple polygons are supported by filling functions (no self-intersections, no holes).
-    // - Concave polygon fill is more expensive than convex one: it has O(N^2) complexity. Provided as a convenience fo user but not used by main library.
-    IMGUI_API void  AddPolyline(const ImVec2* points, int num_points, ImU32 col, ImDrawFlags flags, float thickness);
+    // - Concave polygon fill is more expensive than convex one: it has O(N^2) complexity. Provided as a convenience of user but not used by main library.
+    IMGUI_API void  AddPolyline(const ImVec2* points, int num_points, ImU32 col, ImDrawFlags flags, float thickness, float miter_limit = -1.0f);
+    IMGUI_API void  AddPolylineLegacy(const ImVec2* points, int num_points, ImU32 col, ImDrawFlags flags, float thickness);
     IMGUI_API void  AddConvexPolyFilled(const ImVec2* points, int num_points, ImU32 col);
     IMGUI_API void  AddConcavePolyFilled(const ImVec2* points, int num_points, ImU32 col);
 
@@ -3102,7 +3118,7 @@ struct ImDrawList
     inline    void  PathLineToMergeDuplicate(const ImVec2& pos)                 { if (_Path.Size == 0 || memcmp(&_Path.Data[_Path.Size - 1], &pos, 8) != 0) _Path.push_back(pos); }
     inline    void  PathFillConvex(ImU32 col)                                   { AddConvexPolyFilled(_Path.Data, _Path.Size, col); _Path.Size = 0; }
     inline    void  PathFillConcave(ImU32 col)                                  { AddConcavePolyFilled(_Path.Data, _Path.Size, col); _Path.Size = 0; }
-    inline    void  PathStroke(ImU32 col, ImDrawFlags flags = 0, float thickness = 1.0f) { AddPolyline(_Path.Data, _Path.Size, col, flags, thickness); _Path.Size = 0; }
+    inline    void  PathStroke(ImU32 col, ImDrawFlags flags = 0, float thickness = 1.0f, float miter_limit = -1.0f) { if (Flags & ImDrawListFlags_LegacyPolyline) AddPolylineLegacy(_Path.Data, _Path.Size, col, flags, thickness); else AddPolyline(_Path.Data, _Path.Size, col, flags, thickness, miter_limit); _Path.Size = 0; }
     IMGUI_API void  PathArcTo(const ImVec2& center, float radius, float a_min, float a_max, int num_segments = 0);
     IMGUI_API void  PathArcToFast(const ImVec2& center, float radius, int a_min_of_12, int a_max_of_12);                // Use precomputed angles for a 12 steps circle
     IMGUI_API void  PathEllipticalArcTo(const ImVec2& center, const ImVec2& radius, float rot, float a_min, float a_max, int num_segments = 0); // Ellipse
@@ -3156,6 +3172,10 @@ struct ImDrawList
     IMGUI_API int   _CalcCircleAutoSegmentCount(float radius) const;
     IMGUI_API void  _PathArcToFastEx(const ImVec2& center, float radius, int a_min_sample, int a_max_sample, int a_step);
     IMGUI_API void  _PathArcToN(const ImVec2& center, float radius, float a_min, float a_max, int num_segments);
+    IMGUI_API void  _PolylineEmitArcs(const ImDrawListPolyline& polyline, int arc_count, float core_radius, float fringe_radius);
+    IMGUI_API void  _PolylineThinAntiAliased(const ImDrawListPolyline& polyline);
+    IMGUI_API void  _PolylineThickAntiAliased(const ImDrawListPolyline& polyline);
+    IMGUI_API void  _PolylineAliased(const ImDrawListPolyline& polyline);
 };
 
 // All draw data to render a Dear ImGui frame

imgui_demo.cpp

@@ -8021,6 +8021,11 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
             HelpMarker("Faster lines using texture data. Require backend to render with bilinear filtering (not point/nearest filtering).");
 
             ImGui::Checkbox("Anti-aliased fill", &style.AntiAliasedFill);
+
+            ImGui::Checkbox("Legacy polyline", &style.LegacyPolyline);
+            ImGui::SameLine();
+            HelpMarker("Legacy polyline is faster for drawing lots of geometry, but does lack of features and robustness.");
+
             ImGui::PushItemWidth(ImGui::GetFontSize() * 8);
             ImGui::DragFloat("Curve Tessellation Tolerance", &style.CurveTessellationTol, 0.02f, 0.10f, 10.0f, "%.2f");
             if (style.CurveTessellationTol < 0.10f) style.CurveTessellationTol = 0.10f;
@@ -9351,7 +9356,7 @@ static void ShowExampleAppCustomRendering(bool* p_open)
             static int curve_segments_override_v = 8;
             static ImVec4 colf = ImVec4(1.0f, 1.0f, 0.4f, 1.0f);
             ImGui::DragFloat("Size", &sz, 0.2f, 2.0f, 100.0f, "%.0f");
-            ImGui::DragFloat("Thickness", &thickness, 0.05f, 1.0f, 8.0f, "%.02f");
+            ImGui::DragFloat("Thickness", &thickness, 0.05f, 0.0f, 8.0f, "%.02f");
             ImGui::SliderInt("N-gon sides", &ngon_sides, 3, 12);
             ImGui::Checkbox("##circlesegmentoverride", &circle_segments_override);
             ImGui::SameLine(0.0f, ImGui::GetStyle().ItemInnerSpacing.x);