Continue adding opengl font support.

README.md

@@ -51,7 +51,7 @@ In `xdg-shell-protocol.cpp` - we need access to `xdg_wm_base_interface` so expor
 #### 3D Rendering
 
 ```bash
-sudo apt-get install libgl-dev libegl1-mesa-dev libglu1-mesa-dev
+sudo apt-get install libgl-dev libegl1-mesa-dev libglu1-mesa-dev libglm-dev
 ```
 
 #### fonts

src/core/Color.h

@@ -7,7 +7,7 @@
 class Color
 {
 public:
-    Color(unsigned r, unsigned g, unsigned b, double a = 1.0);
+    Color(unsigned r = 0, unsigned g = 0, unsigned b = 0, double a = 1.0);
 
     static std::shared_ptr<Color> CreateShared(unsigned r, unsigned g, unsigned b, double a = 1.0);
     static std::unique_ptr<Color> Create(unsigned r, unsigned g, unsigned b, double a = 1.0);

src/core/file_utilities/File.cpp

@@ -113,6 +113,22 @@ std::vector<std::string> File::readLines()
     return content;
 }
 
+std::string File::read()
+{
+    if (!PathExists())
+    {
+        return {};
+    }
+
+    Open(false);
+
+    std::stringstream buffer;
+    buffer << mInHandle->rdbuf();
+
+    Close();
+    return buffer.str();
+}
+
 std::string File::getBaseFilename(const Path& path)
 {
     return path.stem().string();

src/core/file_utilities/File.h

@@ -36,6 +36,8 @@ public:
 
     std::vector<std::string> readLines();
 
+    std::string read();
+
     static std::string getBaseFilename(const Path& path);
 
     bool PathExists() const;

src/fonts/BasicFontEngine.h

@@ -3,6 +3,7 @@
 #include "IFontEngine.h"
 
 #include "Image.h"
+#include "FontGlyph.h"
 
 class BasicFontEngine : public IFontEngine
 {
@@ -10,5 +11,5 @@ class BasicFontEngine : public IFontEngine
 
     virtual void loadFontFace(const std::filesystem::path& fontFile, int penSize = 16){};
 
-    virtual std::unique_ptr<Image<unsigned char> > loadGlyph(unsigned charCode){return nullptr;};
+    virtual std::unique_ptr<FontGlyph> loadGlyph(unsigned charCode){return nullptr;};
 };

src/fonts/CMakeLists.txt

@@ -5,6 +5,7 @@ list(APPEND fonts_LIB_INCLUDES
     FontReader.cpp
     TrueTypeFont.cpp
     FontsManager.cpp
+    FontGlyph.cpp
     )
     
 if(UNIX)

src/fonts/FontGlyph.cpp

@@ -0,0 +1,43 @@
+#include "FontGlyph.h"
+
+FontGlyph::FontGlyph(unsigned width, unsigned height, unsigned bearingX, unsigned bearingY,
+        unsigned advanceX, std::unique_ptr<Image<unsigned char> > image)
+    : mImage(std::move(image)),
+      mWidth(width),
+      mHeight(height),
+      mBearingX(mBearingX),
+      mBearingY(mBearingY),
+      mAdvanceX(mAdvanceX)
+{
+
+}
+
+Image<unsigned char>* FontGlyph::getImage() const
+{
+    return mImage.get();
+}
+
+unsigned FontGlyph::getWidth() const
+{
+    return mWidth;
+}
+
+unsigned FontGlyph::getHeight() const
+{
+    return mHeight;
+}
+
+unsigned FontGlyph::getBearingX() const
+{
+    return mBearingX;
+}
+
+unsigned FontGlyph::getBearingY() const
+{
+    return mBearingY;
+}
+
+unsigned FontGlyph::getAdvanceX() const
+{
+    return mAdvanceX;
+}

src/fonts/FontGlyph.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <memory>
+
+#include "Image.h"
+
+class FontGlyph
+{
+
+public:
+    FontGlyph(unsigned width, unsigned height, unsigned bearingX, unsigned bearingY,
+            unsigned advanceX, std::unique_ptr<Image<unsigned char> > image);
+
+    Image<unsigned char>* getImage() const;
+
+    unsigned getWidth() const;
+    unsigned getHeight() const;
+    unsigned getBearingX() const;
+    unsigned getBearingY() const;
+    unsigned getAdvanceX() const;
+
+private:
+    unsigned mWidth{0};
+    unsigned mHeight{0};
+    unsigned mBearingX{0};
+    unsigned mBearingY{0};
+    unsigned mAdvanceX{0};
+    std::unique_ptr<Image<unsigned char> > mImage;
+};

src/fonts/FontItem.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <filesystem>
+#include <string>
+
+class FontItem
+{
+public:
+    FontItem(const std::string& faceName = "Arial", unsigned size = 16)
+        : mFaceName(faceName),
+          mSize(size)
+    {
+
+    }
+
+    bool hasPath() const
+    {
+        return !mPath.empty();
+    }
+
+    const std::filesystem::path& getPath() const
+    {
+        return mPath;
+    }
+
+    void setPath(std::filesystem::path path)
+    {
+        mPath = path;
+    }
+
+private:
+    unsigned mSize{16};
+    std::string mFaceName;
+    std::filesystem::path mPath;
+};

src/fonts/FontReader.h

@@ -3,8 +3,8 @@
 #include <string>
 #include <memory>
 #include <vector>
-#include "IFont.h"
 #include "File.h"
+#include "IFont.h"
 
 class File;
 

src/fonts/FontsManager.cpp

@@ -20,4 +20,20 @@ IFontEngine* FontsManager::getFontEngine() const
     return mFontEngine.get();
 }
 
+FontGlyph* FontsManager::getGlyph(char c)
+{
+    auto iter = mGlyphs.find(c);
+    if(iter != mGlyphs.end())
+    {
+        return iter->second.get();
+    }
+    else
+    {
+        auto glyph = mFontEngine->loadGlyph(c);
+        auto glyph_ptr = glyph.get();
+        mGlyphs[c] = std::move(glyph);
+        return glyph_ptr;
+    }
+}
+
 

src/fonts/FontsManager.h

@@ -2,8 +2,10 @@
 
 #include <memory>
 #include <string>
+#include <unordered_map>
 
 class IFontEngine;
+class FontGlyph;
 
 class FontsManager
 {
@@ -13,8 +15,12 @@ public:
 
     IFontEngine* getFontEngine() const;
 
+    FontGlyph* getGlyph(char c);
+
 private:
     std::unique_ptr<IFontEngine> mFontEngine;
+
+    std::unordered_map<char, std::unique_ptr<FontGlyph> > mGlyphs;
 };
 
 using FontsManagerPtr = std::unique_ptr<FontsManager>;

src/fonts/FreeTypeFontEngine.cpp

@@ -2,6 +2,7 @@
 
 #include "Image.h"
 #include "FileLogger.h"
+#include "FontGlyph.h"
 
 void FreeTypeFontEngine::initialize()
 {
@@ -37,7 +38,7 @@ void FreeTypeFontEngine::loadFontFace(const std::filesystem::path& fontFile, int
     FT_Set_Pixel_Sizes(mWorkingFontFace, penSize, 0);
 }
 
-std::unique_ptr<Image<unsigned char> > FreeTypeFontEngine::loadGlyph(unsigned charCode)
+std::unique_ptr<FontGlyph> FreeTypeFontEngine::loadGlyph(unsigned charCode)
 {
     auto glyph_index = FT_Get_Char_Index( mWorkingFontFace, 65 );
     if (glyph_index == 0)
@@ -83,5 +84,13 @@ std::unique_ptr<Image<unsigned char> > FreeTypeFontEngine::loadGlyph(unsigned ch
         }
     }
     image->setData(data);
-    return image;
+
+    auto glyph = std::make_unique<FontGlyph>(mWorkingFontFace->glyph->bitmap.width,
+            mWorkingFontFace->glyph->bitmap.rows,
+            mWorkingFontFace->glyph->bitmap_left,
+            mWorkingFontFace->glyph->bitmap_top,
+            mWorkingFontFace->glyph->advance.x,
+            std::move(image));
+
+    return glyph;
 }

src/fonts/FreeTypeFontEngine.h

@@ -19,7 +19,7 @@ public:
 
     void loadFontFace(const std::filesystem::path& fontFile, int penSize = 16) override;
 
-    std::unique_ptr<Image<unsigned char> > loadGlyph(unsigned charCode) override;
+    std::unique_ptr<FontGlyph> loadGlyph(unsigned charCode) override;
 
 private:
     std::filesystem::path mSystemFontLocation{"/usr/share/fonts/"};

src/fonts/IFontEngine.h

@@ -3,8 +3,7 @@
 #include <memory>
 #include <filesystem>
 
-template<typename T>
-class Image;
+class FontGlyph;
 
 class IFontEngine
 {
@@ -16,5 +15,5 @@ public:
 
     virtual void loadFontFace(const std::filesystem::path& fontFile, int penSize = 16) = 0;
 
-    virtual std::unique_ptr<Image<unsigned char> > loadGlyph(unsigned charCode) = 0;
+    virtual std::unique_ptr<FontGlyph> loadGlyph(unsigned charCode) = 0;
 };

src/fonts/TrueTypeFont.h

@@ -1,9 +1,8 @@
 #pragma once
 
-#include "IFont.h"
-
 #include <iostream>
 #include <stdint.h>
+#include "IFont.h"
 
 class TrueTypeFont : public IFont
 {

src/graphics/CMakeLists.txt

@@ -19,8 +19,14 @@ set(OpenGL_GL_PREFERENCE "GLVND")
 find_package(OpenGL QUIET)
 if (OpenGL_FOUND)
     list(APPEND platform_LIBS OpenGL::GL OpenGL::GLU)
-    list(APPEND graphics_LIB_INCLUDES opengl/OpenGlPainter.cpp)
-    list(APPEND graphics_HEADERS opengl/OpenGlPainter.h)
+    list(APPEND graphics_LIB_INCLUDES 
+            opengl/OpenGlPainter.cpp
+            opengl/OpenGlFontTexture.cpp
+            opengl/OpenGlShaderProgram.cpp)
+    list(APPEND graphics_HEADERS 
+        opengl/OpenGlPainter.h
+        opengl/OpenGlFontTexture.h
+        opengl/OpenGlShaderProgram.h)
 else()
     message(STATUS "OpenGL headers not found - skipping OpenGL support")
 endif()

src/graphics/DrawingContext.cpp

@@ -2,6 +2,8 @@
 
 #include "AbstractPainter.h"
 #include "OpenGlPainter.h"
+#include "OpenGlShaderProgram.h"
+#include "OpenGlFontTexture.h"
 #include "RasterPainter.h"
 #include "Grid.h"
 #include "TriMesh.h"
@@ -40,6 +42,11 @@ DrawingSurface* DrawingContext::getSurface() const
     return mSurface;
 }
 
+FontsManager* DrawingContext::getFontsManager() const
+{
+    return mFontsManager;
+}
+
 void DrawingContext::paint()
 {
     mScene->update(mFontsManager, mDrawingMode == DrawingMode::RASTER ? mSurface->getImage() : nullptr);

src/graphics/DrawingContext.h

@@ -25,6 +25,8 @@ public:
 
     DrawingSurface* getSurface() const;
 
+    FontsManager* getFontsManager() const;
+
     void paint();
 
 private:

src/graphics/opengl/OpenGlFontTexture.cpp

@@ -0,0 +1,36 @@
+#include "OpenGlFontTexture.h"
+
+#include "FontGlyph.h"
+#include "Image.h"
+
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+
+OpenGlFontTexture::OpenGlFontTexture(FontGlyph* glyph)
+    : mGlyph(glyph)
+{
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+
+    glGenTextures(1, &mHandle);
+    glBindTexture(GL_TEXTURE_2D, mHandle);
+
+    auto buffer = glyph->getImage()->getDataPtr();
+
+    glTexImage2D(
+        GL_TEXTURE_2D,
+        0,
+        GL_RED,
+        mGlyph->getWidth(),
+        mGlyph->getHeight(),
+        0,
+        GL_RED,
+        GL_UNSIGNED_BYTE,
+        buffer
+    );
+
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+}

src/graphics/opengl/OpenGlFontTexture.h

@@ -0,0 +1,13 @@
+#pragma once
+
+class FontGlyph;
+
+class OpenGlFontTexture
+{
+public:
+    OpenGlFontTexture(FontGlyph* glyph);
+
+private:
+    unsigned int mHandle{0};
+    FontGlyph* mGlyph{nullptr};
+};

src/graphics/opengl/OpenGlPainter.cpp

@@ -5,6 +5,15 @@
 #include "Scene.h"
 #include "TriMesh.h"
 
+#include "FontsManager.h"
+#include "FontGlyph.h"
+
+#include "OpenGlFontTexture.h"
+#include "OpenGlShaderProgram.h"
+#include "TextData.h"
+
+#include "File.h"
+
 #ifdef _WIN32
 #include <windows.h>
 #endif
@@ -14,30 +23,18 @@
 #include <GL/glu.h>
 #include <GL/glx.h>
 
+#include <glm/glm.hpp>
+#include <glm/gtc/matrix_transform.hpp>
+#include <glm/gtc/type_ptr.hpp>
+
 #include <iostream>
 
-const char* vertexShaderSource = "#version 330 core\n"
-    "layout (location = 0) in vec3 aPos;\n"
-    "void main()\n"
-    "{\n"
-    "   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
-    "}\0";
-
-
-const char* fragmentShaderSource = "#version 330 core\n"
-        "out vec4 FragColor;\n"
-        "void main()\n"
-        "{\n"
-        "FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
-        "}\n";
-
-
 OpenGlPainter::OpenGlPainter()
 {
 
 }
 
-void OpenGlPainter::initialize()
+void OpenGlPainter::initializeMeshShader()
 {
     if (auto context = glXGetCurrentContext())
     {
@@ -54,99 +51,70 @@ void OpenGlPainter::initialize()
     glGetIntegerv(GL_MINOR_VERSION, &minor_version);
     std::cout << "Using opengl version " << major_version << "|" << minor_version << std::endl;
 
-    std::cout << "Creating opengl painter" << std::endl;
-    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
-    glShaderSource(vertexShader, 1, &vertexShaderSource, nullptr);
-    glCompileShader(vertexShader);
+    auto vert_shader_path = std::filesystem::path(__FILE__).parent_path() / "shaders/default.vert";
+    auto frag_shader_path = std::filesystem::path(__FILE__).parent_path() / "shaders/default.frag";
 
-    int  success;
-    char infoLog[512];
-    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
-    if(!success)
-    {
-        glGetShaderInfoLog(vertexShader, 512, nullptr, infoLog);
-        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED: " << std::string(infoLog) << std::endl;
-
-        if (auto errCode = glGetError(); errCode != GL_NO_ERROR)
-        {
-            auto errString = gluErrorString(errCode);
-            std::cout << "Got gl error" << errString << std::endl;
+    mMeshShaderProgram = std::make_unique<OpenGlShaderProgram>(vert_shader_path, frag_shader_path);
 }
+
+void OpenGlPainter::initializeTextShader()
+{
+    auto vert_shader_path = std::filesystem::path(__FILE__).parent_path() / "shaders/text.vert";
+    auto frag_shader_path = std::filesystem::path(__FILE__).parent_path() / "shaders/text.frag";
+
+    mTextShaderProgram = std::make_unique<OpenGlShaderProgram>(vert_shader_path, frag_shader_path);
+}
+
+void OpenGlPainter::renderTextLayer(const TextData& textData, DrawingContext* context)
+{
+    if (!mTextShaderProgram)
+    {
+        initializeTextShader();
+    }
+
+    auto first_char = textData.mContent[0];
+    auto iter = mFontTextures.find(first_char);
+    OpenGlFontTexture* working_texture{nullptr};
+    if (iter == mFontTextures.end())
+    {
+        auto glyph = context->getFontsManager()->getGlyph(first_char);
+        auto new_texture = std::make_unique<OpenGlFontTexture>(nullptr);
+        working_texture = new_texture.get();
+        mFontTextures[first_char] = std::move(new_texture);
     }
     else
     {
-        std::cout << "Shader compiled ok" << std::endl;
-        if (auto errCode = glGetError(); errCode != GL_NO_ERROR)
+        working_texture = iter->second.get();
+    }
+
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+}
+
+void OpenGlPainter::renderMeshLayer(TriMesh* mesh, DrawingContext* context)
 {
-            auto errString = gluErrorString(errCode);
-            std::cout << "Got gl error after ok" << errString << std::endl;
-        }
-    }
-
-    unsigned int fragmentShader;
-    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
-    glShaderSource(fragmentShader, 1, &fragmentShaderSource, nullptr);
-    glCompileShader(fragmentShader);
-
-    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
-
-    if(!success)
+    if (!mMeshShaderProgram)
     {
-        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
-        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED: " << infoLog << std::endl;
+        initializeMeshShader();
     }
 
-    mShaderProgram = glCreateProgram();
-
-    glAttachShader(mShaderProgram, vertexShader);
-    glAttachShader(mShaderProgram, fragmentShader);
-    glLinkProgram(mShaderProgram);
-
-    glGetProgramiv(mShaderProgram, GL_LINK_STATUS, &success);
-    if(!success)
-    {
-        glGetProgramInfoLog(mShaderProgram, 512, NULL, infoLog);
-        std::cout << "Shader linking FAILED\n" << infoLog << std::endl;
-    }
-
-    glDeleteShader(vertexShader);
-    glDeleteShader(fragmentShader);
-
-    mInitialized = true;
-}
-
-void OpenGlPainter::paint(DrawingContext* context)
-{
-    if (!mInitialized)
-    {
-        initialize();
-    }
-
-    auto surface = context->getSurface();
-    const auto width = double(surface->getWidth());
-    const auto height = double(surface->getHeight());
-    const auto num_mesh = context->getScene()->getNumMeshes();
-
-    glViewport(0, 0, width, height);
-    //glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
-    //glScissor(0, 0, width, height);
-    //glMatrixMode(GL_PROJECTION);
-    //glLoadIdentity();
-
-    glClearColor(0.5, 0.5, 1.0, 0.0);
-    glClear(GL_COLOR_BUFFER_BIT);
-
-    //glMatrixMode(GL_MODELVIEW);
-   //glLoadIdentity();
-
     float vertices[] = {
-        -0.5f, -0.5f, 0.0f,
-         0.5f, -0.5f, 0.0f,
-         0.0f,  0.5f, 0.0f
+         0.5f,  0.5f, 0.0f,  // top right
+         0.5f, -0.5f, 0.0f,  // bottom right
+        -0.5f, -0.5f, 0.0f,  // bottom left
+        -0.5f,  0.5f, 0.0f   // top left
+    };
+
+    unsigned int indices[] = {  // note that we start from 0!
+        0, 1, 3,   // first triangle
+        1, 2, 3    // second triangle
     };
     unsigned int vbo{0};
     glGenBuffers(1, &vbo);
 
+    unsigned int EBO;
+    glGenBuffers(1, &EBO);
+
     unsigned int VAO;
     glGenVertexArrays(1, &VAO);
     glBindVertexArray(VAO);
@@ -154,14 +122,22 @@ void OpenGlPainter::paint(DrawingContext* context)
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
+    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
+
     glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(0);
 
-    glUseProgram(mShaderProgram);
+    int vertexColorLocation = glGetUniformLocation(mMeshShaderProgram->getHandle(), "ourColor");
+
+    glUseProgram(mMeshShaderProgram->getHandle());
     glBindVertexArray(VAO);
 
-    glDrawArrays(GL_TRIANGLES, 0, 3);
+    glUniform4f(vertexColorLocation, 0.0f, 1.0, 0.0f, 1.0f);
 
+    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
+    glBindVertexArray(0);
     /*
     std::cout << "Bounds are : " << width << " | " << height << std::endl;
 
@@ -207,6 +183,31 @@ void OpenGlPainter::paint(DrawingContext* context)
         break;
     }
     */
+}
+
+void OpenGlPainter::paint(DrawingContext* context)
+{
+    auto surface = context->getSurface();
+    const auto width = double(surface->getWidth());
+    const auto height = double(surface->getHeight());
+
+    glViewport(0, 0, width, height);
+    //glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
+    //glScissor(0, 0, width, height);
+    //glMatrixMode(GL_PROJECTION);
+    //glLoadIdentity();
+
+    glClearColor(0.5, 0.5, 1.0, 0.0);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    //glMatrixMode(GL_MODELVIEW);
+   //glLoadIdentity();
+
+    const auto num_mesh = context->getScene()->getNumMeshes();
+    //renderMeshLayer(nullptr, context);
+
+    auto text_data = context->getScene()->getTextData();
+    renderTextLayer(text_data[0], context);
 
     glFlush();
 }

src/graphics/opengl/OpenGlPainter.h

@@ -2,21 +2,33 @@
 
 #include "AbstractPainter.h"
 
+#include <unordered_map>
+#include <memory>
+
 class DrawingContext;
+class OpenGlFontTexture;
+class OpenGlShaderProgram;
+
+class TextData;
+class TriMesh;
 
 class OpenGlPainter : public AbstractPainter
 {
 public:
-
     OpenGlPainter();
 
-
-    void initialize();
     void paint(DrawingContext* context) override;
 
 private:
-    bool mInitialized{false};
-    unsigned int mShaderProgram{0};
+    void initializeMeshShader();
+    void initializeTextShader();
+
+    void renderTextLayer(const TextData& textData, DrawingContext* context);
+    void renderMeshLayer(TriMesh* mesh, DrawingContext* context);
+
+    std::unique_ptr<OpenGlShaderProgram> mMeshShaderProgram;
+    std::unique_ptr<OpenGlShaderProgram> mTextShaderProgram;
+    std::unordered_map<char, std::unique_ptr<OpenGlFontTexture> > mFontTextures;
 };
 
 

src/graphics/opengl/OpenGlShaderProgram.cpp

@@ -0,0 +1,68 @@
+#include "OpenGlShaderProgram.h"
+
+#include "File.h"
+#include "FileLogger.h"
+
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glu.h>
+
+OpenGlShaderProgram::OpenGlShaderProgram(const Path& vertShaderPath, const Path& fragShaderPath)
+{
+    const auto vert_shader_source = File(vertShaderPath).read();
+    const auto frag_shader_source = File(fragShaderPath).read();
+
+    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
+
+    const char* vert_source = vert_shader_source.c_str();
+    glShaderSource(vertexShader, 1, &vert_source, nullptr);
+    glCompileShader(vertexShader);
+
+    int  success;
+    char infoLog[512];
+    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
+    if(!success)
+    {
+        glGetShaderInfoLog(vertexShader, 512, nullptr, infoLog);
+        MLOG_ERROR("ERROR::SHADER::VERTEX::COMPILATION_FAILED: " << infoLog);
+        if (auto errCode = glGetError(); errCode != GL_NO_ERROR)
+        {
+            auto errString = gluErrorString(errCode);
+            MLOG_ERROR("Got gl error " << errString);
+        }
+    }
+
+    unsigned int fragmentShader;
+    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+    const char* frag_source = frag_shader_source.c_str();
+    glShaderSource(fragmentShader, 1, &frag_source, nullptr);
+    glCompileShader(fragmentShader);
+
+    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
+    if(!success)
+    {
+        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
+        MLOG_ERROR("ERROR::SHADER::FRAGMENT::COMPILATION_FAILED: " << infoLog);
+    }
+
+    mHandle = glCreateProgram();
+
+    glAttachShader(mHandle, vertexShader);
+    glAttachShader(mHandle, fragmentShader);
+    glLinkProgram(mHandle);
+
+    glGetProgramiv(mHandle, GL_LINK_STATUS, &success);
+    if(!success)
+    {
+        glGetProgramInfoLog(mHandle, 512, NULL, infoLog);
+        MLOG_ERROR("Shader linking FAILED: " << infoLog);
+    }
+
+    glDeleteShader(vertexShader);
+    glDeleteShader(fragmentShader);
+}
+
+unsigned int OpenGlShaderProgram::getHandle() const
+{
+    return mHandle;
+}

src/graphics/opengl/OpenGlShaderProgram.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <filesystem>
+
+using Path = std::filesystem::path;
+
+class OpenGlShaderProgram
+{
+public:
+    OpenGlShaderProgram(const Path& vertShaderPath, const Path& fragShaderPath);
+
+    unsigned int getHandle() const;
+private:
+    unsigned int mHandle{0};
+};

src/graphics/opengl/shaders/default.frag

@@ -0,0 +1,11 @@
+#version 330 core
+out vec4 FragColor;
+  
+in vec4 vertexColor; // the input variable from the vertex shader (same name and same type)  
+
+uniform vec4 ourColor; // we set this variable in the OpenGL code.
+
+void main()
+{
+    FragColor = ourColor;
+} 

src/graphics/opengl/shaders/default.vert

@@ -0,0 +1,10 @@
+#version 330 core
+layout (location = 0) in vec3 aPos; // the position variable has attribute position 0
+  
+out vec4 vertexColor; // specify a color output to the fragment shader
+
+void main()
+{
+    gl_Position = vec4(aPos, 1.0); // see how we directly give a vec3 to vec4's constructor
+    vertexColor = vec4(aPos.x, aPos.y, 0.0, 1.0); // set the output variable to a dark-red color
+}

src/graphics/opengl/shaders/text.frag

@@ -0,0 +1,12 @@
+#version 330 core
+in vec2 TexCoords;
+out vec4 color;
+
+uniform sampler2D text;
+uniform vec3 textColor;
+
+void main()
+{    
+    vec4 sampled = vec4(1.0, 1.0, 1.0, texture(text, TexCoords).r);
+    color = vec4(textColor, 1.0) * sampled;
+} 

src/graphics/opengl/shaders/text.vert

@@ -0,0 +1,11 @@
+#version 330 core
+layout (location = 0) in vec4 vertex; // <vec2 pos, vec2 tex>
+out vec2 TexCoords;
+
+uniform mat4 projection;
+
+void main()
+{
+    gl_Position = projection * vec4(vertex.xy, 0.0, 1.0);
+    TexCoords = vertex.zw;
+}  

src/visual_elements/Scene.cpp

@@ -34,25 +34,28 @@ void Scene::update(FontsManager* fontsManager, Image<unsigned char>* image)
                     node->update(fontsManager);
                     layer->setIsDirty(false);
                 }
-
                 mWorkingMeshs.push_back(dynamic_cast<TriMesh*>(node->getMesh()));
                 mTextures.push_back(nullptr);
             }
             else
             {
-                auto node = layer->getTextNode();
+                auto node = dynamic_cast<TextNode*>(layer->getTextNode());
                 if (layer->getIsDirty())
                 {
                     node->update(fontsManager);
                     layer->setIsDirty(false);
                 }
-                mWorkingMeshs.push_back(dynamic_cast<TriMesh*>(node->getMesh()));
-                mTextures.push_back(node->getTexture());
+                mTextData.push_back(node->getTextData());
             }
         }
     }
 }
 
+const std::vector<TextData>& Scene::getTextData() const
+{
+    return mTextData;
+}
+
 void Scene::processRectangleNode(RectangleNode* node)
 {
 

src/visual_elements/Scene.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include "TextData.h"
+
 #include <vector>
 #include <memory>
 
@@ -15,6 +17,7 @@ class Image;
 class Scene
 {
 public:
+
     Scene() = default;
 
     void syncLayers(const std::vector<VisualLayer*>& layers);
@@ -27,11 +30,14 @@ public:
 
     Image<unsigned char>* getTexture(std::size_t idx) const;
 
-private:
+    const std::vector<TextData>& getTextData() const;
 
+private:
     void processRectangleNode(RectangleNode* node);
 
-    std::vector<TriMesh*> mWorkingMeshs;
     std::vector<VisualLayer*> mLayers;
+    std::vector<TriMesh*> mWorkingMeshs;
     std::vector<Image<unsigned char>* >  mTextures;
+
+    std::vector<TextData> mTextData;
 };

src/visual_elements/TextData.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "DiscretePoint.h"
+#include "Color.h"
+#include "FontItem.h"
+
+class TextData
+{
+public:
+    TextData() = default;
+    DiscretePoint mLocation;
+    std::string mContent;
+    Color mFillColor;
+    Color mStrokeColor;
+    FontItem mFont;
+};

src/visual_elements/TextNode.cpp

@@ -4,17 +4,18 @@
 #include "FontsManager.h"
 #include "IFontEngine.h"
 #include "MeshPrimitives.h"
+#include "FontItem.h"
 
 #include "Color.h"
 
 TextNode::TextNode(const std::string& content, const DiscretePoint& loc)
-    :   AbstractVisualNode(loc),
-        mContent(content),
-        mFontLabel("fixed"),
-        mFillColor(Color(255, 255, 255)),
-        mStrokeColor(Color(0, 0, 0))
+    :   AbstractVisualNode(loc)
 {
-// https://en.wikipedia.org/wiki/Fixed_(typeface)#:~:text=misc%2Dfixed%20is%20a%20collection,to%20a%20single%20font%20family.
+    mTextData.mContent = content;
+    mTextData.mFont = FontItem("Arial", 16);
+    mTextData.mLocation = loc;
+    mTextData.mFillColor = Color(255, 255, 255);
+    mTextData.mStrokeColor = Color(0, 0, 0);
 }
 
 TextNode::~TextNode()
@@ -29,36 +30,36 @@ std::unique_ptr<TextNode> TextNode::Create(const std::string& content, const Dis
 
 const Color&  TextNode::getFillColor() const
 {
-    return mFillColor;
+    return mTextData.mFillColor;
 }
 const Color&  TextNode::getStrokeColor() const
 {
-    return mStrokeColor;
+    return mTextData.mStrokeColor;
 }
 
 std::string TextNode::getFontLabel() const
 {
-    return mFontLabel;
+    return {};
 }
 
 std::string TextNode::getContent() const
 {
-    return mContent;
+    return mTextData.mContent;
 }
 
 void TextNode::setContent(const std::string& content)
 {
-    mContent = content;
+    mTextData.mContent = content;
 }
 
 void TextNode::setFillColor(const Color& color)
 {
-    mFillColor = color;
+    mTextData.mFillColor = color;
 }
 
 void TextNode::setStrokeColor(const Color& color)
 {
-    mStrokeColor = color;
+    mTextData.mStrokeColor = color;
 }
 
 void TextNode::update(FontsManager* drawingManager)
@@ -67,32 +68,17 @@ void TextNode::update(FontsManager* drawingManager)
     updateTexture(drawingManager);
 }
 
+const TextData& TextNode::getTextData() const
+{
+    return mTextData;
+}
+
 void TextNode::updateMesh()
 {
-    double font_height = 16;
-    double font_width = 16;
 
-    double text_width = mContent.size() * font_width;
-
-    const auto rect = Rectangle(mLocation, text_width, font_height);
-
-    auto mesh = MeshPrimitives::build(rect);
-    auto color = Color(0, 0, 0, 1.0);
-
-    mesh->addConstantFaceVectorAttribute("Color", color.getAsVectorDouble());
-    mMesh = std::move(mesh);
 }
 
 void TextNode::updateTexture(FontsManager* fontsManager)
 {
-    fontsManager->getFontEngine()->loadFontFace("truetype/msttcorefonts/arial.ttf");
-    auto glyph = fontsManager->getFontEngine()->loadGlyph('A');
 
-    if (!glyph)
-    {
-        return;
-    }
-
-    mTexture = std::make_unique<Image<unsigned char> >(glyph->getWidth(), glyph->getHeight());
-    mTexture->setData(glyph->getData());
 }

src/visual_elements/TextNode.h

@@ -4,12 +4,12 @@
 
 #include "AbstractVisualNode.h"
 #include "Color.h"
+#include "FontItem.h"
+#include "TextData.h"
 
 #include <memory>
 #include <string>
 
-class Color;
-
 class TextNode : public AbstractVisualNode
 {
 public:
@@ -24,6 +24,9 @@ public:
 
     std::string getContent() const;
     std::string getFontLabel() const;
+
+    const TextData& getTextData() const;
+
     void setContent(const std::string& content);
     void setFillColor(const Color& color);
     void setStrokeColor(const Color& color);
@@ -34,10 +37,7 @@ private:
     void updateMesh() override;
     void updateTexture(FontsManager* fontsManager) override;
 
-    std::string mContent;
-    std::string mFontLabel;
-    Color mFillColor;
-    Color mStrokeColor;
+    TextData mTextData;
 };
 
 using TextNodetr = std::unique_ptr<TextNode>;

src/windows/ui_interfaces/AbstractUiInterface.h

@@ -3,6 +3,7 @@
 #include <memory>
 #include "IFontEngine.h"
 #include "FontsManager.h"
+#include "FontGlyph.h"
 
 namespace mt
 {

test/fonts/TestFreeTypeFontEngine.cpp

@@ -1,5 +1,6 @@
 
 #include "FreeTypeFontEngine.h"
+#include "FontGlyph.h"
 #include "Image.h"
 
 #include <iostream>