private static float CalcPixelSize(TopologyFace face, int height)
{
// See http://www.freetype.org/freetype2/docs/tutorial/step2.html
// Chapter: Scaling Distances to Device Space
// BBox suits better than Height (baseline-to-baseline distance), because it can enclose all the glyphs in the font face.
var designHeight = (float)face.BBox.Top - (float)face.BBox.Bottom;
var scale = height / designHeight;
var pixelSize = scale * face.UnitsPerEM;
return(pixelSize);
}
private void RenderFont(Font font, TopologyFace face)
{
var pixels = new Color4[TextureSize * TextureSize];
int x = 0;
int y = 0;
foreach (var @char in Characters)
{
uint glyphIndex = face.GetCharIndex(@char);
face.LoadGlyph(glyphIndex, LoadFlags.Default, LoadTarget.Normal);
if (face.Glyph.Metrics.Width == 0)
{
continue;
}
face.Glyph.RenderGlyph(RenderMode.Normal);
var bitmap = face.Glyph.Bitmap;
if (x + bitmap.Width + 1 >= TextureSize)
{
x = 0;
y += Height + 1;
}
if (y + Height + 1 >= TextureSize)
{
AddFontTexture(font, pixels);
pixels = new Color4[TextureSize * TextureSize];
x = y = 0;
}
var verticalOffset = Height - face.Glyph.BitmapTop + face.Size.Metrics.Descender.Round();
CopyBitmap(bitmap, pixels, x, y + verticalOffset);
var uv0 = new Vector2(x, y) / TextureSize;
var uv1 = new Vector2(x + bitmap.Width, y + Height) / TextureSize;
var bearingX = (float)face.Glyph.Metrics.HorizontalBearingX;
var fontChar = new FontChar()
{
Char = @char,
Width = bitmap.Width,
Height = Height,
TextureIndex = font.Textures.Count,
ACWidths = new Vector2(
bearingX.Round(),
((float)face.Glyph.Metrics.HorizontalAdvance - (float)face.Glyph.Metrics.Width - bearingX).Round()
),
UV0 = uv0,
UV1 = uv1,
};
x += bitmap.Width + 1;
// Iterate through kerning pairs
foreach (var prevChar in Characters)
{
uint prevGlyphIndex = face.GetCharIndex(prevChar);
var kerning = (float)face.GetKerning(prevGlyphIndex, glyphIndex, KerningMode.Default).X;
// Round kerning to prevent blurring
kerning = kerning.Round();
if (kerning != 0)
{
if (fontChar.KerningPairs == null)
{
fontChar.KerningPairs = new List <KerningPair>();
}
fontChar.KerningPairs.Add(new KerningPair()
{
Char = prevChar, Kerning = kerning
});
}
}
font.CharSource.Add(fontChar);
}
AddFontTexture(font, pixels);
// Add the whitespace character
font.CharSource.Add(new FontChar()
{
Char = ' ',
Width = ((float)Height / 5).Round(),
Height = Height,
});
}
