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// Std. Includes
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#include <iostream>
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#include <map>
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#include <string>
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// GLEW
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#define GLEW_STATIC
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#include <GL/glew.h>
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// GLFW
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#include <GLFW/glfw3.h>
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// GLM
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#include <glm/glm.hpp>
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#include <glm/gtc/matrix_transform.hpp>
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#include <glm/gtc/type_ptr.hpp>
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// FreeType
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#include <ft2build.h>
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#include FT_FREETYPE_H
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// GL includes
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#include "Shader.h"
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// Properties
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const GLuint WIDTH = 800, HEIGHT = 600;
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/// Holds all state information relevant to a character as loaded using FreeType
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struct Character {
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GLuint TextureID; // ID handle of the glyph texture
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glm::ivec2 Size; // Size of glyph
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glm::ivec2 Bearing; // Offset from baseline to left/top of glyph
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GLuint Advance; // Horizontal offset to advance to next glyph
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};
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std::map<GLchar, Character> Characters;
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GLuint VAO, VBO;
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void RenderText(Shader &shader, std::string text, GLfloat x, GLfloat y, GLfloat scale, glm::vec3 color);
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// The MAIN function, from here we start our application and run the Game loop
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int main()
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{
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// Init GLFW
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glfwInit();
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glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
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glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
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glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
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GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "CubeWorld", nullptr, nullptr); // Windowed
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glfwMakeContextCurrent(window);
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// Initialize GLEW to setup the OpenGL Function pointers
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glewExperimental = GL_TRUE;
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glewInit();
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// Define the viewport dimensions
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glViewport(0, 0, WIDTH, HEIGHT);
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// Set OpenGL options
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glEnable(GL_CULL_FACE);
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glEnable(GL_BLEND);
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glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
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// Compile and setup the shader
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Shader shader("shaders/text.vs", "shaders/text.frag");
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glm::mat4 projection = glm::ortho(0.0f, static_cast<GLfloat>(WIDTH), 0.0f, static_cast<GLfloat>(HEIGHT));
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shader.Use();
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glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
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// FreeType
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FT_Library ft;
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// All functions return a value different than 0 whenever an error occurred
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if (FT_Init_FreeType(&ft))
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std::cout << "ERROR::FREETYPE: Could not init FreeType Library" << std::endl;
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// Load font as face
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FT_Face face;
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if (FT_New_Face(ft, "arial.ttf", 0, &face))
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std::cout << "ERROR::FREETYPE: Failed to load font" << std::endl;
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// Set size to load glyphs as
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FT_Set_Pixel_Sizes(face, 0, 48);
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// Disable byte-alignment restriction
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glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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// Load first 128 characters of ASCII set
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for (GLubyte c = 0; c < 128; c++)
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{
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// Load character glyph
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if (FT_Load_Char(face, c, FT_LOAD_RENDER))
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{
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std::cout << "ERROR::FREETYTPE: Failed to load Glyph" << std::endl;
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continue;
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}
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// Generate texture
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GLuint texture;
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glGenTextures(1, &texture);
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glBindTexture(GL_TEXTURE_2D, texture);
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glTexImage2D(
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GL_TEXTURE_2D,
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0,
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GL_RED,
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face->glyph->bitmap.width,
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face->glyph->bitmap.rows,
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0,
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GL_RED,
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GL_UNSIGNED_BYTE,
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face->glyph->bitmap.buffer
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);
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// Set texture options
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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// Now store character for later use
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Character character = {
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texture,
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glm::ivec2(face->glyph->bitmap.width, face->glyph->bitmap.rows),
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glm::ivec2(face->glyph->bitmap_left, face->glyph->bitmap_top),
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face->glyph->advance.x
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};
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Characters.insert(std::pair<GLchar, Character>(c, character));
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}
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glBindTexture(GL_TEXTURE_2D, 0);
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// Destroy FreeType once we're finished
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FT_Done_Face(face);
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FT_Done_FreeType(ft);
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// Configure VAO/VBO for texture quads
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glGenVertexArrays(1, &VAO);
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glGenBuffers(1, &VBO);
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glBindVertexArray(VAO);
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glBindBuffer(GL_ARRAY_BUFFER, VBO);
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glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat)* 6 * 4, NULL, GL_DYNAMIC_DRAW);
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glEnableVertexAttribArray(0);
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glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), 0);
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glBindBuffer(GL_ARRAY_BUFFER, 0);
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glBindVertexArray(0);
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// Game loop
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while (!glfwWindowShouldClose(window))
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{
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// Check and call events
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glfwPollEvents();
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// Clear the colorbuffer
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glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
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glClear(GL_COLOR_BUFFER_BIT);
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RenderText(shader, "This is group UI", 25.0f, 25.0f, 1.0f, glm::vec3(0.5, 0.8f, 0.2f));
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RenderText(shader, "Digital Media class1301", 540.0f, 570.0f, 0.5f, glm::vec3(0.3, 0.7f, 0.9f));
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// Swap the buffers
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glfwSwapBuffers(window);
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}
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glfwTerminate();
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return 0;
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}
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void RenderText(Shader &shader, std::string text, GLfloat x, GLfloat y, GLfloat scale, glm::vec3 color)
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{
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// Activate corresponding render state
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shader.Use();
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glUniform3f(glGetUniformLocation(shader.Program, "textColor"), color.x, color.y, color.z);
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glActiveTexture(GL_TEXTURE0);
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glBindVertexArray(VAO);
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// Iterate through all characters
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std::string::const_iterator c;
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for (c = text.begin(); c != text.end(); c++)
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{
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Character ch = Characters[*c];
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GLfloat xpos = x + ch.Bearing.x * scale;
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GLfloat ypos = y - (ch.Size.y - ch.Bearing.y) * scale;
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GLfloat w = ch.Size.x * scale;
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GLfloat h = ch.Size.y * scale;
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// Update VBO for each character
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GLfloat vertices[6][4] = {
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{ xpos, ypos + h, 0.0, 0.0 },
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{ xpos, ypos, 0.0, 1.0 },
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{ xpos + w, ypos, 1.0, 1.0 },
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{ xpos, ypos + h, 0.0, 0.0 },
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{ xpos + w, ypos, 1.0, 1.0 },
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{ xpos + w, ypos + h, 1.0, 0.0 }
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};
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// Render glyph texture over quad
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glBindTexture(GL_TEXTURE_2D, ch.TextureID);
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// Update content of VBO memory
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glBindBuffer(GL_ARRAY_BUFFER, VBO);
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glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices); // Be sure to use glBufferSubData and not glBufferData
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glBindBuffer(GL_ARRAY_BUFFER, 0);
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// Render quad
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glDrawArrays(GL_TRIANGLES, 0, 6);
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// Now advance cursors for next glyph (note that advance is number of 1/64 pixels)
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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))
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}
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glBindVertexArray(0);
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glBindTexture(GL_TEXTURE_2D, 0);
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}
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