How to generate MSDF texture directly from FreeType FT_Outline?

[ffbh123456]

Hi, I am trying to generate MSDF glyphs directly from FreeType using msdfgen.
I load the glyph outline like this:

FT_Error error = FT_Load_Glyph(face, glyphIndex, FT_LOAD_NO_BITMAP);
if (error) {
    return;
}

FT_GlyphSlot slot = face->glyph;
if (slot->format != FT_GLYPH_FORMAT_OUTLINE) {
    return;
}

const FT_Outline& outline = slot->outline;

I would like to generate MSDF texture data directly from the FreeType outline.
Is there an example for it.

[Chlumsky]

You can pretty much use the first example in the readme but you can skip the initialize / loadFont / destroy parts and instead of loadGlyph you would use the function readFreetypeOutline, that's pretty much it.

[ffbh123456]

        msdfgen::Shape shape{};
        msdfgen::readFreetypeOutline(shape, &face->glyph->outline);
        shape.normalize();
        edgeColoringSimple(shape, 3.0);
        msdfgen::SDFTransformation transformation(msdfgen::Projection(64.0, msdfgen::Vector2(0.125, 0.125)),
                                                  msdfgen::Range(0.125));

        msdfgen::Bitmap<Float, 3> msdf(64, 64);
        generateMSDF(msdf, shape, transformation);

        MipData colors{};
        colors.Reinitialize(msdf.width(), msdf.height());
        for (Int i = 0; i < msdf.width(); ++i)
        {
            for (Int j = 0; j < msdf.height(); ++j)
            {
                Float r = msdf(i, j)[0];
                Float g = msdf(i, j)[1];
                Float b = msdf(i, j)[2];
                colors.SetPixel(i, j, Color(r, g, b, 1));
            }
        }

@Chlumsky
I tried code like this, and the resulting font texture is this, seems wrong?
below image is 12 font text in total.

[Chlumsky]

You have to set the transformation so that the glyph is actually in the frame.

[ffbh123456]

I'm new to msdfgen and not sure how to set the transformation correctly, Could you show how to modify this code so it actually works?

[Chlumsky]

I'm not ChatGPT. The outline coordinates are spread out over some area depending on the font. You need to transform them to the rectangle between [0, 0] and [SDF width, height]. This is the purpose of the Projection object, which consists of scale and translation. This is a pretty general concept. Also, you should set the third argument of readFreetypeOutline to 1 or the scale is different.

[ffbh123456]

I finally got it working.

I tried many approaches during that time, and at one point my Mac seemed broken — my app hit a segfault on startup and tools like CMake stopped working. After restarting macOS everything was fine again. I can’t remember exactly what I did, but the only issue I recall is that I called Bitmap->T *operator()(int x, int y); many times with out-of-range x and y. Before using your project, I never encountered this even once. Have you experienced anything like this?