Golang Pow2Image Examples

Example #1

File: font.go Project: nobonobo/gltext

// 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
}

Example #2

File: font.go Project: nullboundary/gltext

// 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
}