Merge branch 'master' into docking

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/imgui_impl_opengl3.cpp
#	imgui.h

.github/workflows/build.yml

@@ -394,7 +394,9 @@ jobs:
 
     - name: Build example_emscripten
       run: |
-        source emsdk-master/emsdk_env.sh
+        pushd emsdk-master
+        source ./emsdk_env.sh
+        popd
         make -C examples/example_emscripten
 
   Static-Analysis:

docs/CHANGELOG.txt

@@ -100,6 +100,32 @@ Other changes:
   to make the examples main.cpp easier to read.
 
 
+-----------------------------------------------------------------------
+ VERSION 1.78 WIP (In Progress)
+-----------------------------------------------------------------------
+
+Other Changes:
+
+- Nav: Fixed clicking on void from not clearing focused window.
+  This would be problematic e.g. in situation where the application relies on io.WantCaptureKeyboard
+  flag being cleared accordingly. (bug introduced in 1.77 WIP on 2020/06/16) (#3344, #2880)
+- InputText, ImDrawList: Fixed assert triggering when drawing single line of text with more
+  than ~16 KB characters. (Note that current code is going to show corrupted display if after
+  clipping, more than 16 KB characters are visible in the same low-level ImDrawList::RenderText
+  call. ImGui-level functions such as TextUnformatted() are not affected. This is quite rare
+  but it will be addressed later). (#3349)
+- 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.
+- ImDrawList: Fixed minor bug introduced in 1.75 where AddCircle() with 12 segments would generate
+  an extra vertex. (This bug was mistakenly marked as fixed in earlier 1.77 release). [@ShironekoBen]
+- Backends: OpenGL3: Added support for glad2 loader. (#3330) [@moritz-h]
+>>>>>>> master
+
+
 -----------------------------------------------------------------------
  VERSION 1.77 (Released 2020-06-29)
 -----------------------------------------------------------------------
@@ -109,7 +135,7 @@ Decorated log: https://github.com/ocornut/imgui/releases/tag/v1.77
 Breaking Changes:
 
 - Removed unnecessary ID (first arg) of ImFontAtlas::AddCustomRectRegular() function. Please
-  note that this is a Beta api and will likely be reworked in order to support multi-DPI accross
+  note that this is a Beta api and will likely be reworked in order to support multi-DPI across
   multiple monitors.
 - Renamed OpenPopupOnItemClick() to OpenPopupContextItem(). Kept inline redirection function (will obsolete).
 - Removed BeginPopupContextWindow(const char*, int mouse_button, bool also_over_items) in favor
@@ -167,8 +193,6 @@ Other Changes:
   VtxOffset was not zero would lead to draw commands with wrong VtxOffset. (#2591)
 - ImDrawList, ImDrawListSplitter, Columns: Fixed an issue where starting a split right after
   a callback draw command would incorrectly override the callback draw command.
-- ImDrawList: Fixed minor bug introduced in 1.75 where AddCircle() with 12 segments would
-  generate an extra unrequired vertex. [@ShironekoBen]
 - Misc, Freetype: Fix for rare case where FT_Get_Char_Index() succeeds but FT_Load_Glyph() fails.
 - Docs: Improved and moved font documentation to docs/FONTS.md so it can be readable on the web.
   Updated various links/wiki accordingly. Added FAQ entry about DPI. (#2861) [@ButternCream, @ocornut]

docs/TODO.txt

@@ -336,7 +336,8 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - font/atlas: dynamic font atlas to avoid baking huge ranges into bitmap and make scaling easier.
  - font/draw: vertical and/or rotated text renderer (#705) - vertical is easier clipping wise
  - font/draw: need to be able to specify wrap start position.
- - font/draw: better reserve policy for large horizontal block of text (shouldn't reserve for all clipped lines)
+ - font/draw: better reserve policy for large horizontal block of text (shouldn't reserve for all clipped lines). also see #3349.
+ - font/draw: fix for drawing 16k+ visible characters in same call.
  - font/draw: underline, squiggle line rendering helpers.
  - font: optimization: for monospace font (like the default one) we can trim IndexXAdvance as long as trailing value is == FallbackXAdvance (need to make sure TAB is still correct), would save on cache line.
  - font: add support for kerning, probably optional. A) perhaps default to (32..128)^2 matrix ~ 9K entries = 36KB, then hash for non-ascii?. B) or sparse lookup into per-char list?

examples/README.txt

@@ -1,5 +1,5 @@
 -----------------------------------------------------------------------
- dear imgui, v1.77
+ dear imgui, v1.78 WIP
 -----------------------------------------------------------------------
  examples/README.txt
  (This is the README file for the examples/ folder. See docs/ for more documentation)
@@ -211,7 +211,7 @@ example_glfw_opengl2/
     GLFW + OpenGL2 example (legacy, fixed pipeline).
     = main.cpp + imgui_impl_glfw.cpp + imgui_impl_opengl2.cpp
     **DO NOT USE OPENGL2 CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)**
-    **Prefer using OPENGL3 code (with gl3w/glew/glad/glbinding, you can replace the OpenGL function loader)**
+    **Prefer using OPENGL3 code (with gl3w/glew/glad/glad2/glbinding, you can replace the OpenGL function loader)**
     This code is mostly provided as a reference to learn about Dear ImGui integration, because it is shorter.
     If your code is using GL3+ context or any semi modern OpenGL calls, using this renderer is likely to
     make things more complicated, will require your code to reset many OpenGL attributes to their initial
@@ -260,7 +260,7 @@ example_sdl_opengl2/
     SDL2 (Win32, Mac, Linux etc.) + OpenGL example (legacy, fixed pipeline).
     = main.cpp + imgui_impl_sdl.cpp + imgui_impl_opengl2.cpp
     **DO NOT USE OPENGL2 CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)**
-    **Prefer using OPENGL3 code (with gl3w/glew/glad/glbinding, you can replace the OpenGL function loader)**
+    **Prefer using OPENGL3 code (with gl3w/glew/glad/glad2/glbinding, you can replace the OpenGL function loader)**
     This code is mostly provided as a reference to learn about Dear ImGui integration, because it is shorter.
     If your code is using GL3+ context or any semi modern OpenGL calls, using this renderer is likely to
     make things more complicated, will require your code to reset many OpenGL attributes to their initial

examples/example_glfw_opengl3/Makefile

@@ -42,6 +42,10 @@ CXXFLAGS += -I../libs/gl3w -DIMGUI_IMPL_OPENGL_LOADER_GL3W
 # SOURCES += ../libs/glad/src/glad.c
 # CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD
 
+## Using OpenGL loader: glad2
+# SOURCES += ../libs/glad/src/gl.c
+# CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD2
+
 ## Using OpenGL loader: glbinding
 ## This assumes a system-wide installation
 ## of either version 3.0.0 (or newer)

examples/example_glfw_opengl3/main.cpp

@@ -17,6 +17,8 @@
 #include <GL/glew.h>            // Initialize with glewInit()
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
 #include <glad/glad.h>          // Initialize with gladLoadGL()
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
+#include <glad/gl.h>            // Initialize with gladLoadGL(...) or gladLoaderLoadGL()
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
 #define GLFW_INCLUDE_NONE       // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
 #include <glbinding/Binding.h>  // Initialize with glbinding::Binding::initialize()
@@ -84,6 +86,8 @@ int main(int, char**)
     bool err = glewInit() != GLEW_OK;
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
     bool err = gladLoadGL() == 0;
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
+    bool err = gladLoadGL(glfwGetProcAddress) == 0; // glad2 recommend using the windowing library loader instead of the (optionally) bundled one.
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
     bool err = false;
     glbinding::Binding::initialize();

examples/example_sdl_opengl3/Makefile

@@ -42,6 +42,10 @@ CXXFLAGS += -I../libs/gl3w -DIMGUI_IMPL_OPENGL_LOADER_GL3W
 # SOURCES += ../libs/glad/src/glad.c
 # CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD
 
+## Using OpenGL loader: glad2
+# SOURCES += ../libs/glad/src/gl.c
+# CXXFLAGS += -I../libs/glad/include -DIMGUI_IMPL_OPENGL_LOADER_GLAD2
+
 ## Using OpenGL loader: glbinding
 ## This assumes a system-wide installation
 ## of either version 3.0.0 (or newer)

examples/example_sdl_opengl3/main.cpp

@@ -19,6 +19,8 @@
 #include <GL/glew.h>            // Initialize with glewInit()
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
 #include <glad/glad.h>          // Initialize with gladLoadGL()
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
+#include <glad/gl.h>            // Initialize with gladLoadGL(...) or gladLoaderLoadGL()
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
 #define GLFW_INCLUDE_NONE       // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
 #include <glbinding/Binding.h>  // Initialize with glbinding::Binding::initialize()
@@ -79,6 +81,8 @@ int main(int, char**)
     bool err = glewInit() != GLEW_OK;
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
     bool err = gladLoadGL() == 0;
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
+    bool err = gladLoadGL((GLADloadfunc)SDL_GL_GetProcAddress) == 0; // glad2 recommend using the windowing library loader instead of the (optionally) bundled one.
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
     bool err = false;
     glbinding::Binding::initialize();

examples/imgui_impl_opengl3.cpp

@@ -15,6 +15,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2020-07-10: OpenGL: Added support for glad2 OpenGL loader.
 //  2020-05-08: OpenGL: Made default GLSL version 150 (instead of 130) on OSX.
 //  2020-04-21: OpenGL: Fixed handling of glClipControl(GL_UPPER_LEFT) by inverting projection matrix.
 //  2020-04-12: OpenGL: Fixed context version check mistakenly testing for 4.0+ instead of 3.2+ to enable ImGuiBackendFlags_RendererHasVtxOffset.
@@ -103,6 +104,8 @@
 #include <GL/glew.h>            // Needs to be initialized with glewInit() in user's code.
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
 #include <glad/glad.h>          // Needs to be initialized with gladLoadGL() in user's code.
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
+#include <glad/gl.h>            // Needs to be initialized with gladLoadGL(...) or gladLoaderLoadGL() in user's code.
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
 #ifndef GLFW_INCLUDE_NONE
 #define GLFW_INCLUDE_NONE       // GLFW including OpenGL headers causes ambiguity or multiple definition errors.
@@ -196,6 +199,8 @@ bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
     gl_loader = "GLEW";
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
     gl_loader = "GLAD";
+#elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
+    gl_loader = "GLAD2";
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
     gl_loader = "glbinding2";
 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3)

examples/imgui_impl_opengl3.h

@@ -50,6 +50,7 @@ IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyDeviceObjects();
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GL3W) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLEW) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLAD) \
+ && !defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3) \
  && !defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
@@ -69,6 +70,8 @@ IMGUI_IMPL_API void     ImGui_ImplOpenGL3_DestroyDeviceObjects();
     #define IMGUI_IMPL_OPENGL_LOADER_GLEW
 #elif __has_include(<glad/glad.h>)
     #define IMGUI_IMPL_OPENGL_LOADER_GLAD
+#elif __has_include(<glad/gl.h>)
+    #define IMGUI_IMPL_OPENGL_LOADER_GLAD2
 #elif __has_include(<GL/gl3w.h>)
     #define IMGUI_IMPL_OPENGL_LOADER_GL3W
 #elif __has_include(<glbinding/glbinding.h>)

imgui.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.77
+// dear imgui, v1.78 WIP
 // (main code and documentation)
 
 // Help:
@@ -961,8 +961,9 @@ ImGuiStyle::ImGuiStyle()
     DisplayWindowPadding    = ImVec2(19,19);    // Window position are clamped to be visible within the display area or monitors by at least this amount. Only applies to regular windows.
     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-aliasing on lines/borders. Disable if you are really short on CPU/GPU.
-    AntiAliasedFill         = true;             // Enable anti-aliasing on filled shapes (rounded rectangles, circles, etc.)
+    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 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.
 
@@ -3518,7 +3519,7 @@ void ImGui::UpdateMouseMovingWindowEndFrame()
                     if (!root_window->TitleBarRect().Contains(g.IO.MouseClickedPos[0]))
                         g.MovingWindow = NULL;
         }
-        else if (root_window != NULL && g.NavWindow != NULL && GetTopMostPopupModal() == NULL)
+        else if (root_window == NULL && g.NavWindow != NULL && GetTopMostPopupModal() == NULL)
         {
             // Clicking on void disable focus
             FocusWindow(NULL);
@@ -3871,6 +3872,8 @@ 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_NoBakedLines))
+        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedLinesUseTex;
     if (g.Style.AntiAliasedFill)
         g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedFill;
     if (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset)
@@ -6816,6 +6819,7 @@ void ImGui::SetCurrentFont(ImFont* font)
 
     ImFontAtlas* atlas = g.Font->ContainerAtlas;
     g.DrawListSharedData.TexUvWhitePixel = atlas->TexUvWhitePixel;
+    g.DrawListSharedData.TexUvLines = atlas->TexUvLines;
     g.DrawListSharedData.Font = g.Font;
     g.DrawListSharedData.FontSize = g.FontSize;
 }

imgui.h

@@ -1,4 +1,4 @@
-// dear imgui, v1.77
+// dear imgui, v1.78 WIP
 // (headers)
 
 // Help:
@@ -60,8 +60,8 @@ 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               "1.77"
-#define IMGUI_VERSION_NUM           17701
+#define IMGUI_VERSION               "1.78 WIP"
+#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 IMGUI_HAS_VIEWPORT          1 // Viewport WIP branch
 #define IMGUI_HAS_DOCK              1 // Docking WIP branch
@@ -158,7 +158,7 @@ typedef int ImGuiMouseCursor;       // -> enum ImGuiMouseCursor_     // Enum: A
 typedef int ImGuiStyleVar;          // -> enum ImGuiStyleVar_        // Enum: A variable identifier for styling
 typedef int ImDrawCornerFlags;      // -> enum ImDrawCornerFlags_    // Flags: for ImDrawList::AddRect(), AddRectFilled() etc.
 typedef int ImDrawListFlags;        // -> enum ImDrawListFlags_      // Flags: for ImDrawList
-typedef int ImFontAtlasFlags;       // -> enum ImFontAtlasFlags_     // Flags: for ImFontAtlas
+typedef int ImFontAtlasFlags;       // -> enum ImFontAtlasFlags_     // Flags: for ImFontAtlas build
 typedef int ImGuiBackendFlags;      // -> enum ImGuiBackendFlags_    // Flags: for io.BackendFlags
 typedef int ImGuiColorEditFlags;    // -> enum ImGuiColorEditFlags_  // Flags: for ColorEdit4(), ColorPicker4() etc.
 typedef int ImGuiConfigFlags;       // -> enum ImGuiConfigFlags_     // Flags: for io.ConfigFlags
@@ -770,7 +770,7 @@ namespace ImGui
     IMGUI_API bool          IsMouseDown(ImGuiMouseButton button);                               // is mouse button held?
     IMGUI_API bool          IsMouseClicked(ImGuiMouseButton button, bool repeat = false);       // did mouse button clicked? (went from !Down to Down)
     IMGUI_API bool          IsMouseReleased(ImGuiMouseButton button);                           // did mouse button released? (went from Down to !Down)
-    IMGUI_API bool          IsMouseDoubleClicked(ImGuiMouseButton button);                      // did mouse button double-clicked? a double-click returns false in IsMouseClicked(). uses io.MouseDoubleClickTime.
+    IMGUI_API bool          IsMouseDoubleClicked(ImGuiMouseButton button);                      // did mouse button double-clicked? (note that a double-click will also report IsMouseClicked() == true)
     IMGUI_API bool          IsMouseHoveringRect(const ImVec2& r_min, const ImVec2& r_max, bool clip = true);// is mouse hovering given bounding rect (in screen space). clipped by current clipping settings, but disregarding of other consideration of focus/window ordering/popup-block.
     IMGUI_API bool          IsMousePosValid(const ImVec2* mouse_pos = NULL);                    // by convention we use (-FLT_MAX,-FLT_MAX) to denote that there is no mouse available
     IMGUI_API bool          IsAnyMouseDown();                                                   // is any mouse button held?
@@ -1513,8 +1513,9 @@ struct ImGuiStyle
     ImVec2      DisplayWindowPadding;       // Window position are clamped to be visible within the display area or monitors 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). We apply per-monitor DPI scaling over this scale. May be removed later.
-    bool        AntiAliasedLines;           // Enable anti-aliasing on lines/borders. Disable if you are really tight on CPU/GPU.
-    bool        AntiAliasedFill;            // Enable anti-aliasing on filled shapes (rounded rectangles, circles, etc.)
+    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];
@@ -2000,6 +2001,11 @@ 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_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]
 // NB: You most likely do NOT need to use draw callbacks just to create your own widget or customized UI rendering,
 // you can poke into the draw list for that! Draw callback may be useful for example to:
@@ -2096,12 +2102,15 @@ enum ImDrawCornerFlags_
     ImDrawCornerFlags_All       = 0xF     // In your function calls you may use ~0 (= all bits sets) instead of ImDrawCornerFlags_All, as a convenience
 };
 
+// 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,  // Lines are anti-aliased (*2 the number of triangles for 1.0f wide line, otherwise *3 the number of triangles)
-    ImDrawListFlags_AntiAliasedFill  = 1 << 1,  // Filled shapes have anti-aliased edges (*2 the number of vertices)
-    ImDrawListFlags_AllowVtxOffset   = 1 << 2   // Can emit 'VtxOffset > 0' to allow large meshes. Set when 'ImGuiBackendFlags_RendererHasVtxOffset' is enabled.
+    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_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.
 };
 
 // Draw command list
@@ -2316,11 +2325,13 @@ struct ImFontAtlasCustomRect
     bool IsPacked() const           { return X != 0xFFFF; }
 };
 
+// Flags for ImFontAtlas build
 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
+    ImFontAtlasFlags_NoMouseCursors     = 1 << 1,   // Don't build software mouse cursors into the atlas (save a little texture memory)
+    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:
@@ -2394,7 +2405,7 @@ struct ImFontAtlas
     // Note: this API may be redesigned later in order to support multi-monitor varying DPI settings.
     IMGUI_API int               AddCustomRectRegular(int width, int height);
     IMGUI_API int               AddCustomRectFontGlyph(ImFont* font, ImWchar id, int width, int height, float advance_x, const ImVec2& offset = ImVec2(0, 0));
-    const ImFontAtlasCustomRect*GetCustomRectByIndex(int index) const { if (index < 0) return NULL; return &CustomRects[index]; }
+    ImFontAtlasCustomRect*      GetCustomRectByIndex(int index) { IM_ASSERT(index >= 0); return &CustomRects[index]; }
 
     // [Internal]
     IMGUI_API void              CalcCustomRectUV(const ImFontAtlasCustomRect* rect, ImVec2* out_uv_min, ImVec2* out_uv_max) const;
@@ -2420,8 +2431,12 @@ struct ImFontAtlas
     ImVec2                      TexUvWhitePixel;    // Texture coordinates to a white pixel
     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;         // Internal data
-    int                         CustomRectIds[1];   // Identifiers of custom texture rectangle used by ImFontAtlas/ImDrawList
+    ImVector<ImFontConfig>      ConfigData;         // Configuration data
+    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                         PackIdLines;        // Custom texture rectangle ID for baked anti-aliased lines
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     typedef ImFontAtlasCustomRect    CustomRect;         // OBSOLETED in 1.72+
@@ -2601,7 +2616,7 @@ struct ImGuiPlatformIO
 struct ImGuiPlatformMonitor
 {
     ImVec2  MainPos, MainSize;      // Coordinates of the area displayed on this monitor (Min = upper left, Max = bottom right)
-    ImVec2  WorkPos, WorkSize;      // Coordinates without task bars / side bars / menu bars. Used to avoid positioning popups/tooltips inside this region. If you don't have this info, please copy the value for MainPos/MainSize. 
+    ImVec2  WorkPos, WorkSize;      // Coordinates without task bars / side bars / menu bars. Used to avoid positioning popups/tooltips inside this region. If you don't have this info, please copy the value for MainPos/MainSize.
     float   DpiScale;               // 1.0f = 96 DPI
     ImGuiPlatformMonitor()          { MainPos = MainSize = WorkPos = WorkSize = ImVec2(0, 0); DpiScale = 1.0f; }
 };

imgui_demo.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.77
+// dear imgui, v1.78 WIP
 // (demo code)
 
 // Help:
@@ -456,6 +456,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
             ImGui::Checkbox("io.ConfigWindowsMoveFromTitleBarOnly", &io.ConfigWindowsMoveFromTitleBarOnly);
             ImGui::Checkbox("io.MouseDrawCursor", &io.MouseDrawCursor);
             ImGui::SameLine(); HelpMarker("Instruct Dear ImGui to render a mouse cursor itself. Note that a mouse cursor rendered via your application GPU rendering path will feel more laggy than hardware cursor, but will be more in sync with your other visuals.\n\nSome desktop applications may use both kinds of cursors (e.g. enable software cursor only when resizing/dragging something).");
+            ImGui::Text("Also see Style->Rendering for rendering options.");
             ImGui::TreePop();
             ImGui::Separator();
         }
@@ -3284,7 +3285,7 @@ static void ShowDemoWindowMisc()
             ImGui::Text("Mouse delta: (%g, %g)", io.MouseDelta.x, io.MouseDelta.y);
             ImGui::Text("Mouse down:");     for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++) if (io.MouseDownDuration[i] >= 0.0f)   { ImGui::SameLine(); ImGui::Text("b%d (%.02f secs)", i, io.MouseDownDuration[i]); }
             ImGui::Text("Mouse clicked:");  for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++) if (ImGui::IsMouseClicked(i))          { ImGui::SameLine(); ImGui::Text("b%d", i); }
-            ImGui::Text("Mouse dblclick:"); for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++) if (ImGui::IsMouseDoubleClicked(i)) { ImGui::SameLine(); ImGui::Text("b%d", i); }
+            ImGui::Text("Mouse dblclick:"); for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++) if (ImGui::IsMouseDoubleClicked(i))    { ImGui::SameLine(); ImGui::Text("b%d", i); }
             ImGui::Text("Mouse released:"); for (int i = 0; i < IM_ARRAYSIZE(io.MouseDown); i++) if (ImGui::IsMouseReleased(i))         { ImGui::SameLine(); ImGui::Text("b%d", i); }
             ImGui::Text("Mouse wheel: %.1f", io.MouseWheel);
 
@@ -3911,6 +3912,8 @@ 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. 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

@@ -1,4 +1,4 @@
-// dear imgui, v1.77
+// dear imgui, v1.78 WIP
 // (drawing and font code)
 
 /*
@@ -364,6 +364,7 @@ ImDrawListSharedData::ImDrawListSharedData()
         ArcFastVtx[i] = ImVec2(ImCos(a), ImSin(a));
     }
     memset(CircleSegmentCounts, 0, sizeof(CircleSegmentCounts)); // This will be set by SetCircleSegmentMaxError()
+    TexUvLines = NULL;
 }
 
 void ImDrawListSharedData::SetCircleSegmentMaxError(float max_error)
@@ -522,7 +523,7 @@ void ImDrawList::_OnChangedVtxOffset()
     // We don't need to compare curr_cmd->VtxOffset != _CmdHeader.VtxOffset because we know it'll be different at the time we call this.
     _VtxCurrentIdx = 0;
     ImDrawCmd* curr_cmd = &CmdBuffer.Data[CmdBuffer.Size - 1];
-    IM_ASSERT(curr_cmd->VtxOffset != _CmdHeader.VtxOffset);
+    //IM_ASSERT(curr_cmd->VtxOffset != _CmdHeader.VtxOffset); // See #3349
     if (curr_cmd->ElemCount != 0)
     {
         AddDrawCmd();
@@ -587,6 +588,9 @@ void ImDrawList::PrimReserve(int idx_count, int vtx_count)
     IM_ASSERT_PARANOID(idx_count >= 0 && vtx_count >= 0);
     if (sizeof(ImDrawIdx) == 2 && (_VtxCurrentIdx + vtx_count >= (1 << 16)) && (Flags & ImDrawListFlags_AllowVtxOffset))
     {
+        // FIXME: In theory we should be testing that vtx_count <64k here.
+        // In practice, RenderText() relies on reserving ahead for a worst case scenario so it is currently useful for us
+        // to not make that check until we rework the text functions to handle clipping and large horizontal lines better.
         _CmdHeader.VtxOffset = VtxBuffer.Size;
         _OnChangedVtxOffset();
     }
@@ -672,25 +676,38 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
         return;
 
     const ImVec2 opaque_uv = _Data->TexUvWhitePixel;
-    int count = points_count;
-    if (!closed)
-        count = points_count - 1;
-
+    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);
+
     if (Flags & ImDrawListFlags_AntiAliasedLines)
     {
         // Anti-aliased stroke
         const float AA_SIZE = 1.0f;
         const ImU32 col_trans = col & ~IM_COL32_A_MASK;
 
-        const int idx_count = thick_line ? count * 18 : count * 12;
-        const int vtx_count = thick_line ? points_count * 4 : points_count * 3;
+        // Thicknesses <1.0 should behave like thickness 1.0
+        thickness = ImMax(thickness, 1.0f);
+        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, 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_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);
         PrimReserve(idx_count, vtx_count);
 
         // Temporary buffer
-        ImVec2* temp_normals = (ImVec2*)alloca(points_count * (thick_line ? 5 : 3) * sizeof(ImVec2)); //-V630
+        // 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 * ((use_texture || !thick_line) ? 3 : 5) * sizeof(ImVec2)); //-V630
         ImVec2* temp_points = temp_normals + points_count;
 
+        // Calculate normals (tangents) for each line segment
         for (int i1 = 0; i1 < count; i1++)
         {
             const int i2 = (i1 + 1) == points_count ? 0 : i1 + 1;
@@ -703,59 +720,111 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
         if (!closed)
             temp_normals[points_count - 1] = temp_normals[points_count - 2];
 
-        if (!thick_line)
+        // If we are drawing a one-pixel-wide line without a texture, or a textured line of any width, we only need 2 or 3 vertices per point
+        if (use_texture || !thick_line)
         {
+            // [PATH 1] Texture-based lines (thick or non-thick)
+            // [PATH 2] Non texture-based lines (non-thick)
+
+            // The width of the geometry we need to draw - this is essentially <thickness> pixels for the line itself, plus "one pixel" for AA.
+            // - In the texture-based path, we don't use AA_SIZE here because the +1 is tied to the generated texture
+            //   (see ImFontAtlasBuildRenderLinesTexData() function), and so alternate values won't work without changes to that code.
+            // - In the non texture-based paths, we would allow AA_SIZE to potentially be != 1.0f with a patch (e.g. fringe_scale patch to
+            //   allow scaling geometry while preserving one-screen-pixel AA fringe).
+            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)
             {
-                temp_points[0] = points[0] + temp_normals[0] * AA_SIZE;
-                temp_points[1] = points[0] - temp_normals[0] * AA_SIZE;
-                temp_points[(points_count-1)*2+0] = points[points_count-1] + temp_normals[points_count-1] * AA_SIZE;
-                temp_points[(points_count-1)*2+1] = points[points_count-1] - temp_normals[points_count-1] * AA_SIZE;
+                temp_points[0] = points[0] + temp_normals[0] * half_draw_size;
+                temp_points[1] = points[0] - temp_normals[0] * half_draw_size;
+                temp_points[(points_count-1)*2+0] = points[points_count-1] + temp_normals[points_count-1] * half_draw_size;
+                temp_points[(points_count-1)*2+1] = points[points_count-1] - temp_normals[points_count-1] * half_draw_size;
             }
 
+            // Generate the indices to form a number of triangles for each line segment, and the vertices for the line edges
+            // This takes points n and n+1 and writes into n+1, with the first point in a closed line being generated from the final one (as n+1 wraps)
             // FIXME-OPT: Merge the different loops, possibly remove the temporary buffer.
-            unsigned int idx1 = _VtxCurrentIdx;
-            for (int i1 = 0; i1 < count; i1++)
+            unsigned int idx1 = _VtxCurrentIdx; // Vertex index for start of line segment
+            for (int i1 = 0; i1 < count; i1++) // i1 is the first point of the line segment
             {
-                const int i2 = (i1 + 1) == points_count ? 0 : i1 + 1;
-                unsigned int idx2 = (i1 + 1) == points_count ? _VtxCurrentIdx : idx1 + 3;
+                const int i2 = (i1 + 1) == points_count ? 0 : i1 + 1; // i2 is the second point of the line segment
+                const unsigned int idx2 = ((i1 + 1) == points_count) ? _VtxCurrentIdx : (idx1 + (use_texture ? 2 : 3)); // Vertex index for end of segment
 
                 // Average normals
                 float dm_x = (temp_normals[i1].x + temp_normals[i2].x) * 0.5f;
                 float dm_y = (temp_normals[i1].y + temp_normals[i2].y) * 0.5f;
                 IM_FIXNORMAL2F(dm_x, dm_y);
-                dm_x *= AA_SIZE;
-                dm_y *= AA_SIZE;
+                dm_x *= half_draw_size; // dm_x, dm_y are offset to the outer edge of the AA area
+                dm_y *= half_draw_size;
 
-                // Add temporary vertices
+                // Add temporary vertexes for the outer edges
                 ImVec2* out_vtx = &temp_points[i2 * 2];
                 out_vtx[0].x = points[i2].x + dm_x;
                 out_vtx[0].y = points[i2].y + dm_y;
                 out_vtx[1].x = points[i2].x - dm_x;
                 out_vtx[1].y = points[i2].y - dm_y;
 
-                // Add indexes
-                _IdxWritePtr[0] = (ImDrawIdx)(idx2+0); _IdxWritePtr[1] = (ImDrawIdx)(idx1+0); _IdxWritePtr[2] = (ImDrawIdx)(idx1+2);
-                _IdxWritePtr[3] = (ImDrawIdx)(idx1+2); _IdxWritePtr[4] = (ImDrawIdx)(idx2+2); _IdxWritePtr[5] = (ImDrawIdx)(idx2+0);
-                _IdxWritePtr[6] = (ImDrawIdx)(idx2+1); _IdxWritePtr[7] = (ImDrawIdx)(idx1+1); _IdxWritePtr[8] = (ImDrawIdx)(idx1+0);
-                _IdxWritePtr[9] = (ImDrawIdx)(idx1+0); _IdxWritePtr[10]= (ImDrawIdx)(idx2+0); _IdxWritePtr[11]= (ImDrawIdx)(idx2+1);
-                _IdxWritePtr += 12;
+                if (use_texture)
+                {
+                    // Add indices for two triangles
+                    _IdxWritePtr[0] = (ImDrawIdx)(idx2 + 0); _IdxWritePtr[1] = (ImDrawIdx)(idx1 + 0); _IdxWritePtr[2] = (ImDrawIdx)(idx1 + 1); // Right tri
+                    _IdxWritePtr[3] = (ImDrawIdx)(idx2 + 1); _IdxWritePtr[4] = (ImDrawIdx)(idx1 + 1); _IdxWritePtr[5] = (ImDrawIdx)(idx2 + 0); // Left tri
+                    _IdxWritePtr += 6;
+                }
+                else
+                {
+                    // Add indexes for four triangles
+                    _IdxWritePtr[0] = (ImDrawIdx)(idx2 + 0); _IdxWritePtr[1] = (ImDrawIdx)(idx1 + 0); _IdxWritePtr[2] = (ImDrawIdx)(idx1 + 2); // Right tri 1
+                    _IdxWritePtr[3] = (ImDrawIdx)(idx1 + 2); _IdxWritePtr[4] = (ImDrawIdx)(idx2 + 2); _IdxWritePtr[5] = (ImDrawIdx)(idx2 + 0); // Right tri 2
+                    _IdxWritePtr[6] = (ImDrawIdx)(idx2 + 1); _IdxWritePtr[7] = (ImDrawIdx)(idx1 + 1); _IdxWritePtr[8] = (ImDrawIdx)(idx1 + 0); // Left tri 1
+                    _IdxWritePtr[9] = (ImDrawIdx)(idx1 + 0); _IdxWritePtr[10] = (ImDrawIdx)(idx2 + 0); _IdxWritePtr[11] = (ImDrawIdx)(idx2 + 1); // Left tri 2
+                    _IdxWritePtr += 12;
+                }
 
                 idx1 = idx2;
             }
 
-            // Add vertices
-            for (int i = 0; i < points_count; i++)
+            // Add vertexes for each point on the line
+            if (use_texture)
             {
-                _VtxWritePtr[0].pos = points[i];          _VtxWritePtr[0].uv = opaque_uv; _VtxWritePtr[0].col = col;
-                _VtxWritePtr[1].pos = temp_points[i*2+0]; _VtxWritePtr[1].uv = opaque_uv; _VtxWritePtr[1].col = col_trans;
-                _VtxWritePtr[2].pos = temp_points[i*2+1]; _VtxWritePtr[2].uv = opaque_uv; _VtxWritePtr[2].col = col_trans;
-                _VtxWritePtr += 3;
+                // If we're using textures we only need to emit the left/right edge vertices
+                ImVec4 tex_uvs = _Data->TexUvLines[integer_thickness];
+                if (fractional_thickness != 0.0f)
+                {
+                    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;
+                    tex_uvs.w = tex_uvs.w + (tex_uvs_1.w - tex_uvs.w) * fractional_thickness;
+                }
+                ImVec2 tex_uv0(tex_uvs.x, tex_uvs.y);
+                ImVec2 tex_uv1(tex_uvs.z, tex_uvs.w);
+                for (int i = 0; i < points_count; i++)
+                {
+                    _VtxWritePtr[0].pos = temp_points[i * 2 + 0]; _VtxWritePtr[0].uv = tex_uv0; _VtxWritePtr[0].col = col; // Left-side outer edge
+                    _VtxWritePtr[1].pos = temp_points[i * 2 + 1]; _VtxWritePtr[1].uv = tex_uv1; _VtxWritePtr[1].col = col; // Right-side outer edge
+                    _VtxWritePtr += 2;
+                }
+            }
+            else
+            {
+                // If we're not using a texture, we need the center vertex as well
+                for (int i = 0; i < points_count; i++)
+                {
+                    _VtxWritePtr[0].pos = points[i];              _VtxWritePtr[0].uv = opaque_uv; _VtxWritePtr[0].col = col;       // Center of line
+                    _VtxWritePtr[1].pos = temp_points[i * 2 + 0]; _VtxWritePtr[1].uv = opaque_uv; _VtxWritePtr[1].col = col_trans; // Left-side outer edge
+                    _VtxWritePtr[2].pos = temp_points[i * 2 + 1]; _VtxWritePtr[2].uv = opaque_uv; _VtxWritePtr[2].col = col_trans; // Right-side outer edge
+                    _VtxWritePtr += 3;
+                }
             }
         }
         else
         {
+            // [PATH 2] Non texture-based lines (thick): we need to draw the solid line core and thus require four vertices per point
             const float half_inner_thickness = (thickness - AA_SIZE) * 0.5f;
+
+            // If line is not closed, the first and last points need to be generated differently as there are no normals to blend
             if (!closed)
             {
                 const int points_last = points_count - 1;
@@ -769,9 +838,11 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
                 temp_points[points_last * 4 + 3] = points[points_last] - temp_normals[points_last] * (half_inner_thickness + AA_SIZE);
             }
 
+            // Generate the indices to form a number of triangles for each line segment, and the vertices for the line edges
+            // This takes points n and n+1 and writes into n+1, with the first point in a closed line being generated from the final one (as n+1 wraps)
             // FIXME-OPT: Merge the different loops, possibly remove the temporary buffer.
-            unsigned int idx1 = _VtxCurrentIdx;
-            for (int i1 = 0; i1 < count; i1++)
+            unsigned int idx1 = _VtxCurrentIdx; // Vertex index for start of line segment
+            for (int i1 = 0; i1 < count; i1++) // i1 is the first point of the line segment
             {
                 const int i2 = (i1 + 1) == points_count ? 0 : (i1 + 1); // i2 is the second point of the line segment
                 const unsigned int idx2 = (i1 + 1) == points_count ? _VtxCurrentIdx : (idx1 + 4); // Vertex index for end of segment
@@ -822,7 +893,7 @@ void ImDrawList::AddPolyline(const ImVec2* points, const int points_count, ImU32
     }
     else
     {
-        // Non Anti-aliased Stroke
+        // [PATH 4] Non texture-based, Non anti-aliased lines
         const int idx_count = count * 6;
         const int vtx_count = count * 4;    // FIXME-OPT: Not sharing edges
         PrimReserve(idx_count, vtx_count);
@@ -1176,7 +1247,7 @@ void ImDrawList::AddCircle(const ImVec2& center, float radius, ImU32 col, int nu
     // Because we are filling a closed shape we remove 1 from the count of segments/points
     const float a_max = (IM_PI * 2.0f) * ((float)num_segments - 1.0f) / (float)num_segments;
     if (num_segments == 12)
-        PathArcToFast(center, radius - 0.5f, 0, 12);
+        PathArcToFast(center, radius - 0.5f, 0, 12 - 1);
     else
         PathArcTo(center, radius - 0.5f, 0.0f, a_max, num_segments - 1);
     PathStroke(col, true, thickness);
@@ -1206,7 +1277,7 @@ void ImDrawList::AddCircleFilled(const ImVec2& center, float radius, ImU32 col,
     // Because we are filling a closed shape we remove 1 from the count of segments/points
     const float a_max = (IM_PI * 2.0f) * ((float)num_segments - 1.0f) / (float)num_segments;
     if (num_segments == 12)
-        PathArcToFast(center, radius, 0, 12);
+        PathArcToFast(center, radius, 0, 12 - 1);
     else
         PathArcTo(center, radius, 0.0f, a_max, num_segments - 1);
     PathFillConvex(col);
@@ -1662,8 +1733,7 @@ ImFontAtlas::ImFontAtlas()
     TexWidth = TexHeight = 0;
     TexUvScale = ImVec2(0.0f, 0.0f);
     TexUvWhitePixel = ImVec2(0.0f, 0.0f);
-    for (int n = 0; n < IM_ARRAYSIZE(CustomRectIds); n++)
-        CustomRectIds[n] = -1;
+    PackIdMouseCursors = PackIdLines = -1;
 }
 
 ImFontAtlas::~ImFontAtlas()
@@ -1691,8 +1761,7 @@ void    ImFontAtlas::ClearInputData()
         }
     ConfigData.clear();
     CustomRects.clear();
-    for (int n = 0; n < IM_ARRAYSIZE(CustomRectIds); n++)
-        CustomRectIds[n] = -1;
+    PackIdMouseCursors = PackIdLines = -1;
 }
 
 void    ImFontAtlas::ClearTexData()
@@ -1932,9 +2001,9 @@ bool ImFontAtlas::GetMouseCursorTexData(ImGuiMouseCursor cursor_type, ImVec2* ou
     if (Flags & ImFontAtlasFlags_NoMouseCursors)
         return false;
 
-    IM_ASSERT(CustomRectIds[0] != -1);
-    ImFontAtlasCustomRect& r = CustomRects[CustomRectIds[0]];
-    ImVec2 pos = FONT_ATLAS_DEFAULT_TEX_CURSOR_DATA[cursor_type][0] + ImVec2((float)r.X, (float)r.Y);
+    IM_ASSERT(PackIdMouseCursors != -1);
+    ImFontAtlasCustomRect* r = GetCustomRectByIndex(PackIdMouseCursors);
+    ImVec2 pos = FONT_ATLAS_DEFAULT_TEX_CURSOR_DATA[cursor_type][0] + ImVec2((float)r->X, (float)r->Y);
     ImVec2 size = FONT_ATLAS_DEFAULT_TEX_CURSOR_DATA[cursor_type][1];
     *out_size = size;
     *out_offset = FONT_ATLAS_DEFAULT_TEX_CURSOR_DATA[cursor_type][2];
@@ -2262,17 +2331,6 @@ bool    ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
     return true;
 }
 
-// Register default custom rectangles (this is called/shared by both the stb_truetype and the FreeType builder)
-void ImFontAtlasBuildInit(ImFontAtlas* atlas)
-{
-    if (atlas->CustomRectIds[0] >= 0)
-        return;
-    if (!(atlas->Flags & ImFontAtlasFlags_NoMouseCursors))
-        atlas->CustomRectIds[0] = atlas->AddCustomRectRegular(FONT_ATLAS_DEFAULT_TEX_DATA_W_HALF * 2 + 1, FONT_ATLAS_DEFAULT_TEX_DATA_H);
-    else
-        atlas->CustomRectIds[0] = atlas->AddCustomRectRegular(2, 2);
-}
-
 void ImFontAtlasBuildSetupFont(ImFontAtlas* atlas, ImFont* font, ImFontConfig* font_config, float ascent, float descent)
 {
     if (!font_config->MergeMode)
@@ -2316,20 +2374,18 @@ void ImFontAtlasBuildPackCustomRects(ImFontAtlas* atlas, void* stbrp_context_opa
 
 static void ImFontAtlasBuildRenderDefaultTexData(ImFontAtlas* atlas)
 {
-    IM_ASSERT(atlas->CustomRectIds[0] >= 0);
-    IM_ASSERT(atlas->TexPixelsAlpha8 != NULL);
-    ImFontAtlasCustomRect& r = atlas->CustomRects[atlas->CustomRectIds[0]];
-    IM_ASSERT(r.IsPacked());
+    ImFontAtlasCustomRect* r = atlas->GetCustomRectByIndex(atlas->PackIdMouseCursors);
+    IM_ASSERT(r->IsPacked());
 
     const int w = atlas->TexWidth;
     if (!(atlas->Flags & ImFontAtlasFlags_NoMouseCursors))
     {
         // Render/copy pixels
-        IM_ASSERT(r.Width == FONT_ATLAS_DEFAULT_TEX_DATA_W_HALF * 2 + 1 && r.Height == FONT_ATLAS_DEFAULT_TEX_DATA_H);
+        IM_ASSERT(r->Width == FONT_ATLAS_DEFAULT_TEX_DATA_W_HALF * 2 + 1 && r->Height == FONT_ATLAS_DEFAULT_TEX_DATA_H);
         for (int y = 0, n = 0; y < FONT_ATLAS_DEFAULT_TEX_DATA_H; y++)
             for (int x = 0; x < FONT_ATLAS_DEFAULT_TEX_DATA_W_HALF; x++, n++)
             {
-                const int offset0 = (int)(r.X + x) + (int)(r.Y + y) * w;
+                const int offset0 = (int)(r->X + x) + (int)(r->Y + y) * w;
                 const int offset1 = offset0 + FONT_ATLAS_DEFAULT_TEX_DATA_W_HALF + 1;
                 atlas->TexPixelsAlpha8[offset0] = FONT_ATLAS_DEFAULT_TEX_DATA_PIXELS[n] == '.' ? 0xFF : 0x00;
                 atlas->TexPixelsAlpha8[offset1] = FONT_ATLAS_DEFAULT_TEX_DATA_PIXELS[n] == 'X' ? 0xFF : 0x00;
@@ -2337,29 +2393,85 @@ static void ImFontAtlasBuildRenderDefaultTexData(ImFontAtlas* atlas)
     }
     else
     {
-        IM_ASSERT(r.Width == 2 && r.Height == 2);
-        const int offset = (int)(r.X) + (int)(r.Y) * w;
+        // Render 4 white pixels
+        IM_ASSERT(r->Width == 2 && r->Height == 2);
+        const int offset = (int)r->X + (int)r->Y * w;
         atlas->TexPixelsAlpha8[offset] = atlas->TexPixelsAlpha8[offset + 1] = atlas->TexPixelsAlpha8[offset + w] = atlas->TexPixelsAlpha8[offset + w + 1] = 0xFF;
     }
-    atlas->TexUvWhitePixel = ImVec2((r.X + 0.5f) * atlas->TexUvScale.x, (r.Y + 0.5f) * atlas->TexUvScale.y);
+    atlas->TexUvWhitePixel = ImVec2((r->X + 0.5f) * atlas->TexUvScale.x, (r->Y + 0.5f) * atlas->TexUvScale.y);
+}
+
+static void ImFontAtlasBuildRenderLinesTexData(ImFontAtlas* atlas)
+{
+    if (atlas->Flags & ImFontAtlasFlags_NoBakedLines)
+        return;
+
+    // This generates a triangular shape in the texture, with the various line widths stacked on top of each other to allow interpolation between them
+    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;
+        unsigned int line_width = n;
+        unsigned int pad_left = (r->Width - line_width) / 2;
+        unsigned int pad_right = r->Width - (pad_left + line_width);
+
+        // Write each slice
+        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
+        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->TexUvLines[n] = ImVec4(uv0.x, half_v, uv1.x, half_v);
+    }
 }
 
+// Note: this is called / shared by both the stb_truetype and the FreeType builder
+void ImFontAtlasBuildInit(ImFontAtlas* atlas)
+{
+    // Register texture region for mouse cursors or standard white pixels
+    if (atlas->PackIdMouseCursors < 0)
+    {
+        if (!(atlas->Flags & ImFontAtlasFlags_NoMouseCursors))
+            atlas->PackIdMouseCursors = atlas->AddCustomRectRegular(FONT_ATLAS_DEFAULT_TEX_DATA_W_HALF * 2 + 1, FONT_ATLAS_DEFAULT_TEX_DATA_H);
+        else
+            atlas->PackIdMouseCursors = atlas->AddCustomRectRegular(2, 2);
+    }
+
+    // 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 block
+    // Render into our custom data blocks
+    IM_ASSERT(atlas->TexPixelsAlpha8 != NULL);
     ImFontAtlasBuildRenderDefaultTexData(atlas);
+    ImFontAtlasBuildRenderLinesTexData(atlas);
 
     // Register custom rectangle glyphs
     for (int i = 0; i < atlas->CustomRects.Size; i++)
     {
-        const ImFontAtlasCustomRect& r = atlas->CustomRects[i];
-        if (r.Font == NULL || r.GlyphID == 0)
+        const ImFontAtlasCustomRect* r = &atlas->CustomRects[i];
+        if (r->Font == NULL || r->GlyphID == 0)
             continue;
 
-        IM_ASSERT(r.Font->ContainerAtlas == atlas);
+        IM_ASSERT(r->Font->ContainerAtlas == atlas);
         ImVec2 uv0, uv1;
-        atlas->CalcCustomRectUV(&r, &uv0, &uv1);
-        r.Font->AddGlyph((ImWchar)r.GlyphID, r.GlyphOffset.x, r.GlyphOffset.y, r.GlyphOffset.x + r.Width, r.GlyphOffset.y + r.Height, uv0.x, uv0.y, uv1.x, uv1.y, r.GlyphAdvanceX);
+        atlas->CalcCustomRectUV(r, &uv0, &uv1);
+        r->Font->AddGlyph((ImWchar)r->GlyphID, r->GlyphOffset.x, r->GlyphOffset.y, r->GlyphOffset.x + r->Width, r->GlyphOffset.y + r->Height, uv0.x, uv0.y, uv1.x, uv1.y, r->GlyphAdvanceX);
     }
 
     // Build all fonts lookup tables

imgui_internal.h

@@ -1,4 +1,4 @@
-// dear imgui, v1.77
+// dear imgui, v1.78 WIP
 // (internal structures/api)
 
 // You may use this file to debug, understand or extend ImGui features but we don't provide any guarantee of forward compatibility!
@@ -560,6 +560,7 @@ 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*   TexUvLines;                 // UV of anti-aliased lines in the atlas
 
     ImDrawListSharedData();
     void SetCircleSegmentMaxError(float max_error);

imgui_widgets.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.77
+// dear imgui, v1.78 WIP
 // (widgets code)
 
 /*