Freetype with C++ not loading all glyphs correctly

Question

I'm using FreeType to load the glyph textures, basically using FT_Load_Char to get the texture, then creating an instance of my custom class Character that contains all the metrics and texture for rendering later:

  for (unsigned int c = min; c < max; c++)
  {
    if (FT_Get_Char_Index(faces[faceIndex].second, c) == 0)
      continue;
    if (FT_Load_Char(faces[faceIndex].second, c, FT_LOAD_RENDER))
    {
      cout << "Error: Failed to load Glyph: " << c << endl;
      continue;
    }
    FT_GlyphSlot glyph = faces[faceIndex].second->glyph;
    GLuint texture;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, glyph->bitmap.width, glyph->bitmap.rows, 0, GL_RED, GL_UNSIGNED_BYTE, glyph->bitmap.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);

    Character character;
    character.texture = texture;
    character.bearingX = glyph->bitmap_left;
    character.bearingY = glyph->bitmap_top;
    character.width = glyph->bitmap.width;
    character.height = glyph->bitmap.rows;
    character.advance = glyph->advance.x;

    characters[faceIndex][c] = character;
    count++;
  }

This works correctly for a vast majority of characters, but typing something like asd-=_+123 will produce the following:

So it's not loading some glyphs correctly like +=-, I am using NotoMono-Regular so it obviously has these basic glyphs

Further debugging by printing out the glyph bitmap buffer gives the following for "bad" characters: bitmap buffer of - gives: α α α α α α α α α α

While for "good" characters it's something like: bitmap buffer of 1 gives: 94

So I think the problem is here, but not sure how to fix it

Answer 1

Character character;
character.texture = texture;
character.bearingX = glyph->bitmap_left;
character.bearingY = glyph->bitmap_top;
character.width = glyph->bitmap.width;
character.height = glyph->bitmap.rows;
character.advance = glyph->advance.x;

As it turns out, using unsigned int for the height and int for bearingY is semantically correct, however, there's is arithmetic down the line that goes like

transformation.translation().y() - (ch.height - ch.bearingY) * size * renderer->aspectRatio

where ch.height - ch.bearingY is implicit "promoted" to unsigned int, then implicitly converted to float, as you can guess, if the expected result of ch.height - ch.bearingY is negative bad things will happen. Who decided unsigned int is greater conversion rank anyways....