LoadGlyph has unexpected size on certain glyphs

[Yuria-Shikibe]

I wonder if this is cause by mistakes in my code.

Here is the effect I expected to get, using freetype render sdf:

This one uses msdf:

Two character here have obvious size difference:

And here is my code generating a msdf bitmap:

export
[[nodiscard]] bitmap load_glyph(
	msdfgen::FontHandle* face,
	msdfgen::unicode_t code,
	unsigned w,
	unsigned h,
	unsigned l,
	unsigned top,
	double range = sdf_image_range
	){
	using namespace msdfgen;
	Shape shape;

	if(loadGlyph(shape, face, code, FONT_SCALING_NONE)){
		bitmap bitmap = {w + sdf_image_boarder, h + sdf_image_boarder};

		shape.inverseYAxis = true;
		shape.orientContours();
		shape.normalize();

		auto bound = shape.getBounds();

		double width = bound.r - bound.l;
		double height = bound.t - bound.b;

		auto scale = bitmap.extent().as<double>().sub(sdf_image_boarder, sdf_image_boarder).div(width, height);

		using sdf_bitmap = Bitmap<float, 3>;

		edgeColoringSimple(shape, 2.5);
		sdf_bitmap msdf(bitmap.width(), bitmap.height());

		auto offx = -bound.l + sdf_image_boarder / 2. / scale.x;
		auto offy = -bound.b + sdf_image_boarder / 2. / scale.y;

		SDFTransformation t(
			Projection(
				Vector2{
					scale.x,
					scale.y
				}, Vector2(
					offx,
					offy
				)), Range(range));
		msdfgen::generateMSDF(msdf, shape, t);
		msdfgen::simulate8bit(msdf);

		msdf::write_to_bitmap(bitmap, msdf);

		return bitmap;
	}

	return {};
}

[Chlumsky]

You are literally setting a different scale for each glyph based on its visual size. Are you sure you have any idea what you're doing? Maybe try adding this symbol: "。" and you will see what the problem is.

[Yuria-Shikibe]

@Chlumsky

You are literally setting a different scale for each glyph based on its visual size. Are you sure you have any idea what you're doing? Maybe try adding this symbol: "。" and you will see what the problem is.

by freetype:

by msdf

I can't tell the difference about the typesettings

[Yuria-Shikibe]

Does this have anything to do with the way I used to layout the glyphs?
I am migrating from my old code using FT_Glyph_Metrics and other freetype things to do the typesetting works. Is this not compatible with msdf loadGlyph ?

[Chlumsky]

I don't know what you're doing exactly, but you definitely need to use the same scale.x, scale.y for all characters.

[Yuria-Shikibe]

I don't know what you're doing exactly, but you definitely need to use the same scale.x, scale.y for all characters.

That did work. Thanks for the correction

changed code:

load_glyph(msdfgen::FontHandle* face, msdfgen::unicode_t code,
	unsigned target_w, unsigned target_h, unsigned font_w, unsigned font_h, double range){

	using namespace msdfgen;
	Shape shape;

	if(loadGlyph(shape, face, code, FONT_SCALING_EM_NORMALIZED)){
		bitmap bitmap = {target_w + sdf_image_boarder, target_h + sdf_image_boarder};

		shape.orientContours();
		shape.normalize();

		const auto bound = shape.getBounds();
		const double height = bound.t - bound.b;
		const auto scale = math::vector2{font_w, font_h}.as<double>();
		
		edgeColoringSimple(shape, 2.5);
		Bitmap<float, 3> msdf(bitmap.width(), bitmap.height());

		auto offx = -bound.l + sdf_image_boarder / 2. / scale.x;
		auto offy = -bound.b - height - sdf_image_boarder / 2. / scale.y;

		SDFTransformation t(
			Projection(
				Vector2{
					scale.x,
					-scale.y
				}, Vector2(
					offx,
					offy
				)), Range(range));
		generateMSDF(msdf, shape, t);
		simulate8bit(msdf);

		write_to_bitmap(bitmap, msdf);

		return bitmap;
	}

	return {};
}