// loadFont loads the given font data. This does not deal with font scaling.
// Scaling should be handled by the independent Bitmap/Truetype loaders.
// We therefore expect the supplied image and charset to already be adjusted
// to the correct font scale.
//
// The image should hold a sprite sheet, defining the graphical layout for
// every glyph. The config describes font metadata.
func loadFont(img *image.RGBA, config *FontConfig) (f *Font, err error) {
f = new(Font)
f.Config = config
// Resize image to next power-of-two.
img = glh.Pow2Image(img).(*image.RGBA)
ib := img.Bounds()
f.Width = ib.Dx()
f.Height = ib.Dy()
// Create the texture itself. It will contain all glyphs.
// Individual glyph-quads display a subset of this texture.
f.Texture = gl.GenTexture()
f.Texture.Bind(gl.TEXTURE_2D)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, ib.Dx(), ib.Dy(), 0,
gl.RGBA, gl.UNSIGNED_BYTE, img.Pix)
// file, err := os.Create("font.png")
// if err != nil {
// log.Fatal(err)
// }
// err = png.Encode(file, img)
// if err != nil {
// log.Fatal(err)
// }
return
}
// loadFont loads the given font data. This does not deal with font scaling.
// Scaling should be handled by the independent Bitmap/Truetype loaders.
// We therefore expect the supplied image and charset to already be adjusted
// to the correct font scale.
//
// The image should hold a sprite sheet, defining the graphical layout for
// every glyph. The config describes font metadata.
func loadFont(img *image.RGBA, config *FontConfig) (f *Font, err error) {
f = new(Font)
f.config = config
// Resize image to next power-of-two.
img = glh.Pow2Image(img).(*image.RGBA)
ib := img.Bounds()
// Create the texture itself. It will contain all glyphs.
// Individual glyph-quads display a subset of this texture.
f.texture = gl.GenTexture()
f.texture.Bind(gl.TEXTURE_2D)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, ib.Dx(), ib.Dy(), 0,
gl.RGBA, gl.UNSIGNED_BYTE, img.Pix)
// Create display lists for each glyph.
f.listbase = gl.GenLists(len(config.Glyphs))
texWidth := float32(ib.Dx())
texHeight := float32(ib.Dy())
for index, glyph := range config.Glyphs {
// Update max glyph bounds.
if glyph.Width > f.maxGlyphWidth {
f.maxGlyphWidth = glyph.Width
}
if glyph.Height > f.maxGlyphHeight {
f.maxGlyphHeight = glyph.Height
}
// Quad width/height
vw := float32(glyph.Width)
vh := float32(glyph.Height)
// Texture coordinate offsets.
tx1 := float32(glyph.X) / texWidth
ty1 := float32(glyph.Y) / texHeight
tx2 := (float32(glyph.X) + vw) / texWidth
ty2 := (float32(glyph.Y) + vh) / texHeight
// Advance width (or height if we render top-to-bottom)
adv := float32(glyph.Advance)
gl.NewList(f.listbase+uint(index), gl.COMPILE)
{
gl.Begin(gl.QUADS)
{
gl.TexCoord2f(tx1, ty2)
gl.Vertex2f(0, 0)
gl.TexCoord2f(tx2, ty2)
gl.Vertex2f(vw, 0)
gl.TexCoord2f(tx2, ty1)
gl.Vertex2f(vw, vh)
gl.TexCoord2f(tx1, ty1)
gl.Vertex2f(0, vh)
}
gl.End()
switch config.Dir {
case LeftToRight:
gl.Translatef(adv, 0, 0)
case RightToLeft:
gl.Translatef(-adv, 0, 0)
case TopToBottom:
gl.Translatef(0, -adv, 0)
}
}
gl.EndList()
}
err = glh.CheckGLError()
return
}