Add draft for text rendering

SConstruct

@@ -19,7 +19,7 @@ env = Environment(tools=['default', 'compilation_db'])
 env.CompilationDatabase()
 
 env.Append(CPPPATH=['cpp/', 'include/'])
-env.Append(LIBS=['glfw', 'dl'])
+env.Append(LIBS=['glfw', 'dl', 'freetype'])
 
 add_third_party_includes(env)
 add_strict_compile_flags(env)

cpp/RenderBackend.cpp

@@ -15,6 +15,11 @@ void RenderBackend::initialize_window(unsigned int width, unsigned int height, S
     window = glfwCreateWindow(width, height, title, NULL, NULL);
     glfwMakeContextCurrent(window);
     gladLoadGLLoader((GLADloadproc)glfwGetProcAddress);
+
+    glEnable(GL_DEPTH_TEST);
+    glEnable(GL_CULL_FACE);
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 }
 
 bool RenderBackend::is_window_created() {

cpp/TextLabel.cpp

@@ -0,0 +1,128 @@
+// Must be the first include
+#include <glad/glad.h>
+
+// Other includes
+#include <GLFW/glfw3.h>
+#include <glm/ext/matrix_clip_space.hpp>
+#include <glm/gtc/type_ptr.hpp>
+
+#include "Gedeng/Logger.h"
+#include "Gedeng/TextLabel.h"
+
+namespace Gedeng {
+
+TextLabel::TextLabel() : shader(Shader("Shader/text.vs", "Shader/text.fs")) {
+    FT_Library ft;
+    if (FT_Init_FreeType(&ft)) {
+        GG_CORE_ERROR("Couldn't create font library!");
+        return;
+    }
+
+    FT_Face face;
+    if (FT_New_Face(ft, "Resources/Fonts/Inter.ttf", 0, &face)) {
+        GG_CORE_ERROR("Couldn't load font from path!");
+        return;
+    }
+
+    // Set size
+    FT_Set_Pixel_Sizes(face, 0, 48);
+
+    // Load first 128 ASCII Characters
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1); // disable byte-alignment restriction
+
+    for (unsigned char c = 0; c < 128; c++) {
+        // load character glyph
+        if (FT_Load_Char(face, c, FT_LOAD_RENDER)) {
+            GG_CORE_ERROR("Couldn't load character glyph!");
+            continue;
+        }
+        // generate texture
+        unsigned int texture;
+        glGenTextures(1, &texture);
+        glBindTexture(GL_TEXTURE_2D, texture);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, face->glyph->bitmap.width, face->glyph->bitmap.rows, 0, GL_RED,
+                     GL_UNSIGNED_BYTE, face->glyph->bitmap.buffer);
+        // set texture options
+        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);
+        // now store character for later use
+        Character character = {texture, glm::ivec2(face->glyph->bitmap.width, face->glyph->bitmap.rows),
+                               glm::ivec2(face->glyph->bitmap_left, face->glyph->bitmap_top),
+                               static_cast<unsigned int>(face->glyph->advance.x)};
+        characters.insert(std::pair<char, Character>(c, character));
+    }
+
+    glBindTexture(GL_TEXTURE_2D, 0);
+
+    // destroy FreeType once we're finished
+    FT_Done_Face(face);
+    FT_Done_FreeType(ft);
+
+    // configure VAO/VBO for texture quads
+    // -----------------------------------
+    glGenVertexArrays(1, &vao);
+    glGenBuffers(1, &vbo);
+    glBindVertexArray(vao);
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 6 * 4, NULL, GL_DYNAMIC_DRAW);
+    glEnableVertexAttribArray(0);
+    glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    glBindVertexArray(0);
+
+    valid = true;
+}
+
+void TextLabel::render_text(String text, float x, float y, float scale, Vector3 color) {
+    // activate corresponding render state
+    shader.use();
+
+    glUniform3f(glGetUniformLocation(shader.ID, "textColor"), color.x, color.y, color.z);
+
+    // FIXME: We need the screen size here... (or UI module size?)
+    glm::mat4 projection = glm::ortho(0.0f, static_cast<float>(500), 0.0f, static_cast<float>(500));
+    glUniformMatrix4fv(glGetUniformLocation(shader.ID, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
+
+    glActiveTexture(GL_TEXTURE0);
+    glBindVertexArray(vao);
+
+    // iterate through all characters
+    for (size_t i = 0; i < text.get_length(); i++) {
+        Character ch = characters[text[i]];
+
+        float xpos = x + ch.bearing.x * scale;
+        float ypos = y - (ch.size.y - ch.bearing.y) * scale;
+
+        float w = ch.size.x * scale;
+        float h = ch.size.y * scale;
+        // update VBO for each character
+        float vertices[6][4] = {
+            {xpos, ypos + h, 0.0f, 0.0f}, {xpos, ypos, 0.0f, 1.0f},     {xpos + w, ypos, 1.0f, 1.0f},
+
+            {xpos, ypos + h, 0.0f, 0.0f}, {xpos + w, ypos, 1.0f, 1.0f}, {xpos + w, ypos + h, 1.0f, 0.0f}};
+        // render glyph texture over quad
+        glBindTexture(GL_TEXTURE_2D, ch.texture_id);
+        // update content of VBO memory
+        glBindBuffer(GL_ARRAY_BUFFER, vbo);
+        glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices),
+                        vertices); // be sure to use glBufferSubData and not glBufferData
+
+        glBindBuffer(GL_ARRAY_BUFFER, 0);
+        // render quad
+        glDrawArrays(GL_TRIANGLES, 0, 6);
+        // now advance cursors for next glyph (note that advance is number of 1/64 pixels)
+        x += (ch.advance >> 6) * scale; // bitshift by 6 to get value in pixels (2^6 = 64 (divide amount of 1/64th
+                                        // pixels by 64 to get amount of pixels))
+    }
+
+    glBindVertexArray(0);
+    glBindTexture(GL_TEXTURE_2D, 0);
+}
+
+bool TextLabel::is_valid() {
+    return valid;
+}
+
+} // namespace Gedeng

include/Gedeng/TextLabel.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <ft2build.h>
+#include <glm/glm.hpp>
+#include <map>
+#include FT_FREETYPE_H
+
+#include "Gedeng/Shader.h"
+#include "Gedeng/String.h"
+#include "Gedeng/Vector3.h"
+
+namespace Gedeng {
+
+class TextLabel {
+  public:
+    TextLabel();
+
+    void render_text(String text, float x, float y, float scale, Vector3 color);
+
+    bool is_valid();
+
+  private:
+    struct Character {
+        unsigned int texture_id; // ID handle of the glyph texture
+        glm::ivec2 size;         // Size of glyph
+        glm::ivec2 bearing;      // Offset from baseline to left/top of glyph
+        unsigned int advance;    // Offset to advance to next glyph
+    };
+
+    std::map<char, Character> characters;
+    unsigned int vao, vbo;
+    bool valid;
+
+    Shader shader;
+};
+
+} // namespace Gedeng

include/Gedeng/Vector3.h

@@ -2,6 +2,14 @@
 
 namespace Gedeng {
 
-class Vector3 {};
+class Vector3 {
+  public:
+    Vector3(float x, float y, float z) : x(x), y(y), z(z) {
+    }
+
+    float x;
+    float y;
+    float z;
+};
 
 } // namespace Gedeng

test/parallax-demo/main.cpp

@@ -1,4 +1,6 @@
 #include "Gedeng/Logger.h"
+#include "Gedeng/TextLabel.h"
+#include "Gedeng/Vector3.h"
 #define GEDENG_MAIN
 #include <Gedeng.h>
 
@@ -68,6 +70,9 @@ class ParallaxApp : public Gedeng::Application {
         // Quad which is rendered onto
         quad_mesh.rotate(delta * 25.0f, glm::normalize(glm::vec3(0.0, 0.0, 1.0)));
         quad_mesh.render(render_shader);
+
+        debug_text.render_text(Gedeng::String("This is sample text"), 25.0f, 25.0f, 1.0f,
+                               Gedeng::Vector3(1.0, 1.0, 0.0));
     }
 
   private:
@@ -86,6 +91,8 @@ class ParallaxApp : public Gedeng::Application {
     Gedeng::Texture normal;
 
     Gedeng::QuadMesh quad_mesh;
+
+    Gedeng::TextLabel debug_text;
 };
 
 Gedeng::Application *Gedeng::create_application() {