Use ImGuiFreeType for better font rendering.

Author: GPSnoopy

CMakeLists.txt

@@ -48,6 +48,7 @@ if (UNIX)
 endif ()
 
 find_package(Boost REQUIRED COMPONENTS exception program_options) 
+find_package(freetype CONFIG REQUIRED)
 find_package(glfw3 CONFIG REQUIRED)
 find_package(glm CONFIG REQUIRED)
 find_package(imgui CONFIG REQUIRED)

src/CMakeLists.txt

@@ -21,6 +21,8 @@ set(src_files_assets
 )
 
 set(src_files_imgui
+	ImGui/imgui_freetype.cpp
+	ImGui/imgui_freetype.h
 	ImGui/imgui_impl_glfw.cpp
 	ImGui/imgui_impl_glfw.h
 	ImGui/imgui_impl_vulkan.cpp
@@ -166,4 +168,4 @@ add_dependencies(${exe_name} Assets)
 set_target_properties(${exe_name} PROPERTIES DEBUG_POSTFIX ${CMAKE_DEBUG_POSTFIX})
 target_include_directories(${exe_name} PRIVATE . ${Boost_INCLUDE_DIRS} ${glfw3_INCLUDE_DIRS} ${glm_INCLUDE_DIRS} ${STB_INCLUDE_DIRS} ${Vulkan_INCLUDE_DIRS})
 target_link_directories(${exe_name} PRIVATE ${Vulkan_LIBRARY})
-target_link_libraries(${exe_name} PRIVATE ${Boost_LIBRARIES} glfw glm::glm imgui::imgui tinyobjloader::tinyobjloader ${Vulkan_LIBRARIES} ${extra_libs})
+target_link_libraries(${exe_name} PRIVATE ${Boost_LIBRARIES} freetype glfw glm::glm imgui::imgui tinyobjloader::tinyobjloader ${Vulkan_LIBRARIES} ${extra_libs})

src/ImGui/imgui_freetype.cpp

@@ -0,0 +1,50 @@
+// dear imgui: FreeType font builder (used as a replacement for the stb_truetype builder)
+// (headers)
+
+#pragma once
+
+#include "imgui.h"      // IMGUI_API
+
+// Forward declarations
+struct ImFontAtlas;
+struct ImFontBuilderIO;
+
+// Hinting greatly impacts visuals (and glyph sizes).
+// - By default, hinting is enabled and the font's native hinter is preferred over the auto-hinter.
+// - When disabled, FreeType generates blurrier glyphs, more or less matches the stb_truetype.h
+// - The Default hinting mode usually looks good, but may distort glyphs in an unusual way.
+// - The Light hinting mode generates fuzzier glyphs but better matches Microsoft's rasterizer.
+// You can set those flags globaly in ImFontAtlas::FontBuilderFlags
+// You can set those flags on a per font basis in ImFontConfig::FontBuilderFlags
+enum ImGuiFreeTypeBuilderFlags
+{
+    ImGuiFreeTypeBuilderFlags_NoHinting     = 1 << 0,   // Disable hinting. This generally generates 'blurrier' bitmap glyphs when the glyph are rendered in any of the anti-aliased modes.
+    ImGuiFreeTypeBuilderFlags_NoAutoHint    = 1 << 1,   // Disable auto-hinter.
+    ImGuiFreeTypeBuilderFlags_ForceAutoHint = 1 << 2,   // Indicates that the auto-hinter is preferred over the font's native hinter.
+    ImGuiFreeTypeBuilderFlags_LightHinting  = 1 << 3,   // A lighter hinting algorithm for gray-level modes. Many generated glyphs are fuzzier but better resemble their original shape. This is achieved by snapping glyphs to the pixel grid only vertically (Y-axis), as is done by Microsoft's ClearType and Adobe's proprietary font renderer. This preserves inter-glyph spacing in horizontal text.
+    ImGuiFreeTypeBuilderFlags_MonoHinting   = 1 << 4,   // Strong hinting algorithm that should only be used for monochrome output.
+    ImGuiFreeTypeBuilderFlags_Bold          = 1 << 5,   // Styling: Should we artificially embolden the font?
+    ImGuiFreeTypeBuilderFlags_Oblique       = 1 << 6,   // Styling: Should we slant the font, emulating italic style?
+    ImGuiFreeTypeBuilderFlags_Monochrome    = 1 << 7,   // Disable anti-aliasing. Combine this with MonoHinting for best results!
+    ImGuiFreeTypeBuilderFlags_LoadColor     = 1 << 8,   // Enable FreeType color-layered glyphs
+    ImGuiFreeTypeBuilderFlags_Bitmap        = 1 << 9    // Enable FreeType bitmap glyphs
+};
+
+namespace ImGuiFreeType
+{
+    // This is automatically assigned when using '#define IMGUI_ENABLE_FREETYPE'.
+    // If you need to dynamically select between multiple builders:
+    // - you can manually assign this builder with 'atlas->FontBuilderIO = ImGuiFreeType::GetBuilderForFreeType()'
+    // - prefer deep-copying this into your own ImFontBuilderIO instance if you use hot-reloading that messes up static data.
+    IMGUI_API const ImFontBuilderIO*    GetBuilderForFreeType();
+
+    // Override allocators. By default ImGuiFreeType will use IM_ALLOC()/IM_FREE()
+    // However, as FreeType does lots of allocations we provide a way for the user to redirect it to a separate memory heap if desired.
+    IMGUI_API void                      SetAllocatorFunctions(void* (*alloc_func)(size_t sz, void* user_data), void (*free_func)(void* ptr, void* user_data), void* user_data = NULL);
+
+    // Obsolete names (will be removed soon)
+    // Prefer using '#define IMGUI_ENABLE_FREETYPE'
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+    static inline bool BuildFontAtlas(ImFontAtlas* atlas, unsigned int flags = 0) { atlas->FontBuilderIO = GetBuilderForFreeType(); atlas->FontBuilderFlags = flags; return atlas->Build(); }
+#endif
+}

src/ImGui/imgui_freetype.h

@@ -13,6 +13,7 @@
 #include "Vulkan/Window.hpp"
 
 #include "imgui.h"
+#include "ImGui/imgui_freetype.h"
 #include "ImGui/imgui_impl_glfw.h"
 #include "ImGui/imgui_impl_vulkan.h"
 
@@ -87,7 +88,8 @@ UserInterface::UserInterface(
 	ImGui::StyleColorsDark();
 	ImGui::GetStyle().ScaleAllSizes(scaleFactor);
 
-	// Upload ImGui fonts
+	// Upload ImGui fonts (use ImGuiFreeType for better font rendering, see https://github.com/ocornut/imgui/tree/master/misc/freetype).
+	io.Fonts->FontBuilderIO = ImGuiFreeType::GetBuilderForFreeType();
 	if (!io.Fonts->AddFontFromFileTTF("../assets/fonts/Cousine-Regular.ttf", 13 * scaleFactor))
 	{
 		Throw(std::runtime_error("failed to load ImGui font"));

src/UserInterface.cpp

@@ -12,6 +12,7 @@ git checkout 2021.04.30
 	boost-exception:x64-linux \
 	boost-program-options:x64-linux \
 	boost-stacktrace:x64-linux \
+	freetype:x64-linux \
 	glfw3:x64-linux \
 	glm:x64-linux \
 	imgui:x64-linux \

vcpkg_linux.sh

@@ -9,6 +9,7 @@ vcpkg.exe install ^
 	boost-exception:x64-windows-static ^
 	boost-program-options:x64-windows-static ^
 	boost-stacktrace:x64-windows-static ^
+	freetype:x64-windows-static ^
 	glfw3:x64-windows-static ^
 	glm:x64-windows-static ^
 	imgui:x64-windows-static ^