C++字体库开发之字符显示四

freetype提取路径，转svg显示

std::string FontPath::toSvg(const Segment &seg) const
{if (seg.pts.empty())return "";std::ostringstream strStream;for (const auto &pt : seg.pts) {if (!strStream.view().empty())strStream << "__";strStream << pt.x;strStream << ",";strStream << pt.y;}return strStream.str();
}std::string FontPath::toSvg() const
{std::string svg;for (const auto &seg : m_points) {if (!svg.empty())svg.append(",");switch (seg.type) {case Type::MOVE:svg.append("M");break;case Type::LINE:svg.append("L");break;case Type::QUAD:svg.append("Q");break;case Type::CONIC:svg.append("C");break;case Type::CUBIC:svg.append("C");break;case Type::CLOSE:svg.append("C");break;default:;}svg.append(" ");svg.append(toSvg(seg));}return svg;
}

["M 31.23,79.50,C 31.23,35.59__77.57,0.00__134.73,0.00,C 191.89,0.00__188.73,35.59__188.73,79.50,C 188.73,123.41__226.89,221.50__169.73,221.50,C 141.98,221.50__35.81,200.32__8.73,171.50,C -19.96,140.96__31.23,102.09__31.23,79.50"]

freetype提取bitmap，控制台打印

void Draw_Bitmap(unsigned char *bitmap, int width, int height)
{std::cout << std::endl;if (bitmap == NULL)return;for (int i = 0; i < height; i++) {for (int j = 0; j < width; j++) {int color = bitmap[i * width + j];if (color == 0) {std::cout << " ";} else {std::cout << "*";}}std::cout << std::endl;}
}

freetype提取bitmap，转纹理贴图

#include <iostream>
#include <map>
#include <string>#include <glad/glad.h>
#include <GLFW/glfw3.h>#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "ftest.h"
#include "fontParse.h"#include "shader.h"void framebuffer_size_callback(GLFWwindow *window, int width, int height);
void processInput(GLFWwindow *window);
void RenderText(Shader &shader, std::string text, float x, float y, float scale, glm::vec3 color);// settings
const unsigned int SCR_WIDTH  = 800;
const unsigned int SCR_HEIGHT = 600;/// Holds all state information relevant to a character as loaded using FreeType
struct Character {unsigned int TextureID;  // ID handle of the glyph textureglm::ivec2   Size;       // Size of glyphglm::ivec2   Bearing;    // Offset from baseline to left/top of glyphunsigned int Advance;    // Horizontal offset to advance to next glyph
};std::map<GLchar, Character> Characters;
unsigned int                VAO, VBO;TEST(Render, TextRender)
{// glfw: initialize and configure// ------------------------------glfwInit();glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);#ifdef __APPLE__glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif// glfw window creation// --------------------GLFWwindow *window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);if (window == NULL) {std::cout << "Failed to create GLFW window" << std::endl;glfwTerminate();return;}glfwMakeContextCurrent(window);glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);// glad: load all OpenGL function pointers// ---------------------------------------if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {std::cout << "Failed to initialize GLAD" << std::endl;return;}// OpenGL state// ------------glEnable(GL_CULL_FACE);glEnable(GL_BLEND);glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);// compile and setup the shader// ----------------------------Shader    shader("text.vs", "text.fs");glm::mat4 projection = glm::ortho(0.0f, static_cast<float>(SCR_WIDTH), 0.0f, static_cast<float>(SCR_HEIGHT));shader.use();glUniformMatrix4fv(glGetUniformLocation(shader.ID, "projection"), 1, GL_FALSE, glm::value_ptr(projection));// disable byte-alignment restrictionglPixelStorei(GL_UNPACK_ALIGNMENT, 1);const char *path    = "D:\\fonts";auto        fontMap = createFontMap(path, FontMapType::FONT_MAP_TYPE_FT);// load first 128 characters of ASCII setfor (unsigned char c = 0; c < 128; c++) {// Load character glyphauto image = getImage(fontMap, c);// generate textureunsigned int texture;glGenTextures(1, &texture);glBindTexture(GL_TEXTURE_2D, texture);glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, image.pitch, image.rows, 0, GL_RED, GL_UNSIGNED_BYTE, image.bitmap);// set texture optionsglTexParameteri(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 useCharacter character = {texture,glm::ivec2(image.width, image.rows),glm::ivec2(image.x_bearing, image.y_bearing),static_cast<unsigned int>(image.bound.width)};Characters.insert(std::pair<char, Character>(c, character));}glBindTexture(GL_TEXTURE_2D, 0);// 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);// render loop// -----------while (!glfwWindowShouldClose(window)) {// input// -----processInput(window);// render// ------glClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);RenderText(shader, "This is sample text", 25.0f, 25.0f, 1.0f, glm::vec3(0.5, 0.8f, 0.2f));RenderText(shader, "(C) LearnOpenGL.com", 540.0f, 570.0f, 0.5f, glm::vec3(0.3, 0.7f, 0.9f));// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)// -------------------------------------------------------------------------------glfwSwapBuffers(window);glfwPollEvents();}glfwTerminate();return;
}// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)glfwSetWindowShouldClose(window, true);
}// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow *window, int width, int height)
{// make sure the viewport matches the new window dimensions; note that width and// height will be significantly larger than specified on retina displays.glViewport(0, 0, width, height);
}// render line of text
// -------------------
void RenderText(Shader &shader, std::string text, float x, float y, float scale, glm::vec3 color)
{// activate corresponding render stateshader.use();glUniform3f(glGetUniformLocation(shader.ID, "textColor"), color.x, color.y, color.z);glActiveTexture(GL_TEXTURE0);glBindVertexArray(VAO);// iterate through all charactersstd::string::const_iterator c;for (c = text.begin(); c != text.end(); c++) {Character ch = Characters[*c];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 characterfloat 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 quadglBindTexture(GL_TEXTURE_2D, ch.TextureID);// update content of VBO memoryglBindBuffer(GL_ARRAY_BUFFER, VBO);glBufferSubData(GL_ARRAY_BUFFER,0,sizeof(vertices),vertices);  // be sure to use glBufferSubData and not glBufferDataglBindBuffer(GL_ARRAY_BUFFER, 0);// render quadglDrawArrays(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))x += ch.Advance;}glBindVertexArray(0);glBindTexture(GL_TEXTURE_2D, 0);
}