refactor font code into classes

engine/font.cpp

@@ -1,5 +1,92 @@
 #include "pch.h"
 #include "font.h"
 
+std::map<kFont, Font> FontManager::m_fonts;
 
+bool Font::load(const char* ttf)
+{
+    FILE* font_file = fopen(ttf, "rb");
+    if (font_file)
+    {
+        fseek(font_file, 0, SEEK_END);
+        long sz = ftell(font_file);
+        auto data = std::make_unique<uint8_t[]>(sz);
+        fseek(font_file, 0, SEEK_SET);
+        auto bytes = fread(data.get(), 1, sz, font_file);
+        assert(bytes==sz);
+        auto bitmap = std::make_unique<uint8_t[]>(w*h);
+        chars.resize(num_chars);
+        int ret = stbtt_BakeFontBitmap(data.get(), 0, 50, bitmap.get(), w, h, start_char, num_chars, chars.data());
+        font_tex.create(w, h, GL_RED, bitmap.get());
+        fclose(font_file);
+        return true;
+    }
+    return false;
+}
 
+bool FontManager::load(kFont id, const char *ttf)
+{
+    return m_fonts[id].load(ttf);
+}
+
+const Font& FontManager::get(kFont id)
+{
+    return m_fonts[id];
+}
+
+bool TextMesh::create()
+{
+    glGenBuffers(2, font_buffers);
+    glGenVertexArrays(1, &font_array);
+    
+    glBindVertexArray(font_array);
+    glEnableVertexAttribArray(0);
+    glEnableVertexAttribArray(1);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, font_buffers[1]);
+    glBindBuffer(GL_ARRAY_BUFFER, font_buffers[0]);
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(glm::vec4), (GLvoid*)0);
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(glm::vec4), (GLvoid*)(sizeof(float)*2));
+    glBindVertexArray(0);
+    return true;
+}
+
+void TextMesh::update(kFont id, const char* text)
+{
+    auto& f = FontManager::get(id);
+    if (f.chars.size())
+    {
+        static char str[64];
+        static int counter = 0;
+        counter++;
+        sprintf(str, "frame %04d", counter);
+        const auto len = strlen(str);
+        float x = 0;
+        float y = 0;
+        std::vector<glm::vec4> v;
+        std::vector<GLushort> idx;
+        for (int i = 0; i < len; i++)
+        {
+            int c = str[i] - f.start_char;
+            stbtt_aligned_quad q;
+            stbtt_GetBakedQuad((stbtt_bakedchar*)f.chars.data(), f.w, f.h, c, &x, &y, &q, true);
+            auto n = v.size();
+            v.emplace_back(q.x0, q.y1, q.s0, q.t1);
+            v.emplace_back(q.x0, q.y0, q.s0, q.t0);
+            v.emplace_back(q.x1, q.y0, q.s1, q.t0);
+            v.emplace_back(q.x1, q.y1, q.s1, q.t1);
+            idx.push_back(n+0);
+            idx.push_back(n+1);
+            idx.push_back(n+2);
+            idx.push_back(n+0);
+            idx.push_back(n+2);
+            idx.push_back(n+3);
+        }
+        font_array_count = (int)idx.size();
+        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, font_buffers[1]);
+        glBufferData(GL_ELEMENT_ARRAY_BUFFER, idx.size() * sizeof(GLushort), idx.data(), GL_STATIC_DRAW);
+        glBindBuffer(GL_ARRAY_BUFFER, font_buffers[0]);
+        glBufferData(GL_ARRAY_BUFFER, v.size() * sizeof(glm::vec4), v.data(), GL_STATIC_DRAW);
+        glBindBuffer(GL_ARRAY_BUFFER, 0);
+        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
+    }
+}