feat(ui): add UI text rendering

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Allow identifying assets in code from their path (#1177. **@GalaxyCrush**).
 - Added an Audio asset (#230, **@Dageus**, **@diogomsmiranda**).
 - Hold function for debug_camera (#1030, **@jdbaracho**).
+- UI text element using MSDF for text rendering (#1300, **@mkuritsu**).
 
 ### Changed
 
@@ -24,6 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Crash when opening the Play Pause menu (**SrGesus**).
 - Duplicated destructor call in AnyVector which caused double free crashes on multiple samples (**@RiscadoA**).
 - Compiler Error when using -O3 flag (#1351, **@SrGesus**).
+- Made canvas draw calls sorted by layer in order to prevent undeterministic behavior when drawing elements with transparency (**@mkuritsu**).
 
 ## [v0.4.0] - 2024-10-13
 

core/include/cubos/core/gl/render_device.hpp

@@ -238,6 +238,7 @@ namespace cubos::core::gl
     /// @ingroup core-gl
     enum class TextureFormat
     {
+        RGB8UInt,
         R8SNorm,     ///< 1 channel 8 bits normalized signed integer.
         R16SNorm,    ///< 1 channel 16 bits normalized signed integer.
         RG8SNorm,    ///< 2 channel 8 bits normalized signed integer.

core/src/gl/ogl_render_device.cpp

@@ -41,6 +41,11 @@ static bool textureFormatToGL(TextureFormat texFormat, GLenum& internalFormat, G
 {
     switch (texFormat)
     {
+    case TextureFormat::RGB8UInt:
+        internalFormat = GL_RGB;
+        format = GL_RGB;
+        type = GL_UNSIGNED_BYTE;
+        break;
     case TextureFormat::R8UNorm:
         internalFormat = GL_R8;
         format = GL_RED;

engine/CMakeLists.txt

@@ -1,6 +1,8 @@
 # engine/CMakeLists.txt
 # Cubos engine build configuration
 
+include(FetchContent)
+
 option(BUILD_ENGINE_SAMPLES "Build cubos engine samples" OFF)
 option(BUILD_ENGINE_TESTS "Build cubos engine tests?" OFF)
 option(BUILD_ENGINE_SHARED "Build cubos engine as shared library?" ON)
@@ -113,10 +115,19 @@ set(CUBOS_ENGINE_SOURCE
 	"src/ui/color_rect/color_rect.cpp"
 	"src/ui/image/plugin.cpp"
 	"src/ui/image/image.cpp"
+	"src/ui/text/plugin.cpp"
+    "src/ui/text/text_stretch.cpp"
+	"src/ui/text/text.cpp"
 
 	"src/fixed_step/plugin.cpp"
 	"src/fixed_step/fixed_delta_time.cpp"
 
+	"src/font/plugin.cpp"
+	"src/font/font.cpp"
+	"src/font/bridge.cpp"
+	"src/font/atlas.cpp"
+	"src/font/atlas_store.cpp"
+
 	"src/render/defaults/plugin.cpp"
 	"src/render/defaults/target.cpp"
 	"src/render/shader/plugin.cpp"
@@ -237,6 +248,41 @@ add_library(stb_image INTERFACE)
 target_include_directories(stb_image SYSTEM INTERFACE "lib/stb_image")
 target_link_libraries(cubos-engine PUBLIC stb_image)
 
+# freetype (msdfgen dependency) - fails to build on windows without this
+set(FT_DISABLE_ZLIB ON)
+set(FT_DISABLE_BZIP2 ON)
+set(FT_DISABLE_PNG ON)
+set(FT_DISABLE_HARFBUZZ ON)
+set(FT_DISABLE_BROTLI ON)
+FetchContent_Declare(freetype
+    GIT_REPOSITORY "https://gitlab.freedesktop.org/freetype/freetype.git"
+    GIT_TAG "VER-2-13-3"
+    SYSTEM
+    FIND_PACKAGE_ARGS
+)
+FetchContent_MakeAvailable(freetype)
+add_library(Freetype::Freetype ALIAS freetype)
+set_property(TARGET freetype PROPERTY POSITION_INDEPENDENT_CODE ON)
+
+# msdf-atlas-gen
+set(MSDF_ATLAS_USE_VCPKG OFF)
+set(MSDF_ATLAS_USE_SKIA OFF)
+set(MSDF_ATLAS_BUILD_STANDALONE OFF)
+set(MSDF_ATLAS_NO_ARTERY_FONT ON)
+set(MSDFGEN_DISABLE_PNG ON)
+set(MSDFGEN_BUILD_STANDALONE OFF)
+FetchContent_Declare(msdf-atlas-gen
+    GIT_REPOSITORY "https://github.com/Chlumsky/msdf-atlas-gen.git"
+    SYSTEM
+    FIND_PACKAGE_ARGS
+)
+FetchContent_MakeAvailable(msdf-atlas-gen)
+# To prevent reallocation errors when compiling engine as a shared library
+set_property(TARGET msdf-atlas-gen PROPERTY POSITION_INDEPENDENT_CODE ON)
+set_property(TARGET msdfgen-core PROPERTY POSITION_INDEPENDENT_CODE ON)
+
+target_link_libraries(cubos-engine PUBLIC msdf-atlas-gen)
+
 # Add engine tests
 if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME AND BUILD_ENGINE_TESTS)
 	add_subdirectory(tests)

engine/assets/font/Roboto-Regular.ttf.meta

@@ -0,0 +1,3 @@
+{
+    "id": "93cbe82e-9c9b-4c25-aa55-5105c1afd0cc"
+}

engine/assets/ui/text.fs

@@ -0,0 +1,36 @@
+#version 330 core
+
+in vec2 texCoord;
+out vec4 out_color;
+uniform sampler2D fontAtlas;
+
+const float pxRange = 4.0;
+
+layout(std140) uniform PerElement
+{
+    vec2 xRange;
+    vec2 yRange;
+    vec4 color;
+    int depth;
+};
+
+float screenPxRange()
+{
+    vec2 unitRange = vec2(pxRange) / vec2(textureSize(fontAtlas, 0));
+    vec2 screenTexSize = vec2(1.0) / fwidth(texCoord);
+    return max(0.5 * dot(unitRange, screenTexSize), 1.0);
+}
+
+float median(float r, float g, float b)
+{
+    return max(min(r, g), min(max(r, g), b));
+}
+
+void main()
+{
+    vec3 msd = texture(fontAtlas, texCoord).rgb;
+    float sd = median(msd.r, msd.g, msd.b);
+    float screenPxDistance = screenPxRange() * (sd - 0.5);
+    float opacity = clamp(screenPxDistance + 0.5, 0.0, 1.0);
+    out_color = mix(vec4(0.0), color, opacity);
+}

engine/assets/ui/text.fs.meta

@@ -0,0 +1,3 @@
+{
+    "id": "b5b43fcb-0ec3-4f3a-9e90-a7b0b9978cc5"
+}

engine/assets/ui/text_element.vs

@@ -0,0 +1,25 @@
+#version 330 core
+
+in vec2 in_position;
+in vec2 in_texCoord;
+
+layout(std140) uniform PerElement
+{
+    vec2 xRange;
+    vec2 yRange;
+    vec4 color;
+    int depth;
+};
+
+out vec2 texCoord;
+
+uniform MVP
+{
+    mat4 mvp;
+};
+
+void main()
+{
+    gl_Position = mvp * (vec4(xRange.x, yRange.x, 0, 0) + vec4(in_position, depth, 1));
+    texCoord = in_texCoord;
+}

engine/assets/ui/text_element.vs.meta

@@ -0,0 +1,3 @@
+{
+    "id": "51c11c57-c819-4a51-806c-853178ec686a"
+}

engine/include/cubos/engine/font/atlas.hpp

@@ -0,0 +1,38 @@
+/// @file
+/// @brief Struct @ref cubos::engine::FontAtlas.
+/// @ingroup font-plugin
+
+#pragma once
+
+#include <unordered_map>
+
+#include <msdf-atlas-gen/msdf-atlas-gen.h>
+
+#include <cubos/core/gl/render_device.hpp>
+#include <cubos/core/reflection/reflect.hpp>
+
+#include <cubos/engine/api.hpp>
+
+namespace cubos::engine
+{
+    /// @brief Class that holds all the necessary data about a font atlas. This font atlas represents the texure
+    /// created from all the different glyphs in a font, that will be then used for drawing the text.
+    ///
+    /// @ingroup font-plugin
+    struct CUBOS_ENGINE_API FontAtlas
+    {
+        CUBOS_REFLECT;
+
+        FontAtlas(msdfgen::FontHandle* font, core::gl::RenderDevice& rd);
+
+        /// @brief GPU texture containing this font atlas.
+        cubos::core::gl::Texture2D texture;
+
+        /// @brief Map from unicode characters to their respective glyph geometry data.
+        std::unordered_map<msdf_atlas::unicode_t, msdf_atlas::GlyphGeometry> glyphs;
+
+        /// @brief Information about the bitmap used to generate the texture.
+        msdfgen::BitmapConstRef<msdfgen::byte, 3> bitmap;
+    };
+
+} // namespace cubos::engine

engine/include/cubos/engine/font/atlas_store.hpp

@@ -0,0 +1,37 @@
+/// @file
+/// @brief Resource @ref cubos::engine::FontAtlasStore.
+/// @ingroup font-plugin
+
+#pragma once
+
+#include <memory>
+#include <unordered_map>
+
+#include <uuid.h>
+
+#include <cubos/core/reflection/reflect.hpp>
+
+#include <cubos/engine/api.hpp>
+#include <cubos/engine/font/atlas.hpp>
+
+namespace cubos::engine
+{
+    struct CUBOS_ENGINE_API FontAtlasStore
+    {
+        CUBOS_REFLECT;
+
+        std::weak_ptr<FontAtlas> retrieve(const uuids::uuid& assetId);
+
+        bool contains(const uuids::uuid& assetId) const;
+
+        void store(const uuids::uuid& assetId, const std::shared_ptr<FontAtlas>& atlas);
+
+        void remove(const uuids::uuid& assetId);
+
+        const std::unordered_map<uuids::uuid, std::weak_ptr<FontAtlas>>& map() const;
+
+    private:
+        std::unordered_map<uuids::uuid, std::weak_ptr<FontAtlas>> mAtlas;
+    };
+
+} // namespace cubos::engine

engine/include/cubos/engine/font/bridge.hpp

@@ -0,0 +1,33 @@
+/// @file
+/// @brief Class @ref cubos::engine::FontBridge.
+/// @ingroup font-plugin
+
+#pragma once
+
+#include <cubos/engine/assets/bridges/file.hpp>
+#include <cubos/engine/font/font.hpp>
+
+namespace cubos::engine
+{
+    /// @brief Bridge which loads and saves @ref Font assets.
+    ///
+    /// @ingroup font-plugin
+    class CUBOS_ENGINE_API FontBridge : public FileBridge
+    {
+    public:
+        FontBridge()
+            : FileBridge(core::reflection::reflect<Font>())
+            , mFtHandle(msdfgen::initializeFreetype())
+        {
+        }
+
+        ~FontBridge() override;
+
+    protected:
+        bool loadFromFile(Assets& assets, const AnyAsset& handle, core::memory::Stream& stream) override;
+        bool saveToFile(const Assets& assets, const AnyAsset& handle, core::memory::Stream& stream) override;
+
+    private:
+        msdfgen::FreetypeHandle* mFtHandle;
+    };
+} // namespace cubos::engine

engine/include/cubos/engine/font/font.hpp

@@ -0,0 +1,30 @@
+/// @file
+/// @brief Struct @ref cubos::engine::Font.
+/// @ingroup font-plugin
+
+#pragma once
+
+#include <msdf-atlas-gen/msdf-atlas-gen.h>
+
+#include <cubos/core/memory/stream.hpp>
+#include <cubos/core/reflection/reflect.hpp>
+
+#include <cubos/engine/api.hpp>
+
+namespace cubos::engine
+{
+    /// @brief Asset containing font data.
+    ///
+    /// @ingroup font-plugin
+    struct CUBOS_ENGINE_API Font
+    {
+        CUBOS_REFLECT;
+
+        /// @brief The handle to the loaded font.
+        msdfgen::FontHandle* fontHandle{nullptr};
+
+        explicit Font(msdfgen::FreetypeHandle* ft, core::memory::Stream& stream);
+        Font(Font&& other) noexcept;
+        ~Font();
+    };
+} // namespace cubos::engine

engine/include/cubos/engine/font/plugin.hpp

@@ -0,0 +1,28 @@
+/// @dir
+/// @brief @ref font-plugin plugin directory.
+
+/// @file
+/// @brief Plugin entry point.
+/// @ingroup font-plugin
+
+#pragma once
+
+#include <cubos/engine/prelude.hpp>
+
+namespace cubos::engine
+{
+    /// @defgroup font-plugin Font
+    /// @ingroup engine
+    /// @brief Adds fonts to @b Cubos using msdfgen.
+    ///
+    /// ## Bridges
+    /// - @ref FontBridge - loads @ref Font assets.
+    ///
+    /// ## Dependencies
+    /// - @ref assets-plugin
+
+    /// @brief Plugin entry function.
+    /// @param cubos @b Cubos main class.
+    /// @ingroup font-plugin
+    CUBOS_ENGINE_API void fontPlugin(Cubos& cubos);
+} // namespace cubos::engine

engine/include/cubos/engine/ui/text/plugin.hpp

@@ -0,0 +1,23 @@
+/// @dir
+/// @brief @ref ui-text-plugin plugin directory.
+
+/// @file
+/// @brief Plugin entry point.
+/// @ingroup ui-text-plugin
+
+#pragma once
+
+#include <cubos/engine/prelude.hpp>
+
+namespace cubos::engine
+{
+    /// @defgroup ui-text-plugin
+    /// @ingroup ui-plugins
+    /// @brief Adds text element to UI.
+
+    /// @brief Plugin entry function.
+    /// @param cubos @b Cubos main class
+    /// @ingroup ui-text-plugin
+    CUBOS_ENGINE_API void uiTextPlugin(Cubos& cubos);
+
+} // namespace cubos::engine