head.go

package skin

import (
	"image"
	"math"
)

// RenderHead renders a 3-dimensional image of the head of a Minecraft player's skin.
func RenderHead(img *image.NRGBA, opts Options) *image.NRGBA {
	if err := validateSkin(img); err != nil {
		panic(err)
	}

	var (
		skin        *image.NRGBA = convertToNRGBA(img)
		scaleDouble float64      = float64(opts.Scale)
		output      *image.NRGBA = image.NewNRGBA(image.Rect(0, 0, 13*opts.Scale+int(math.Floor(scaleDouble*0.855)), 16*opts.Scale))
		frontHead   *image.NRGBA = removeTransparency(extract(skin, HeadFront))
		topHead     *image.NRGBA = rotate90(flipHorizontal(removeTransparency(extract(skin, HeadTop))))
		rightHead   *image.NRGBA = removeTransparency(extract(skin, HeadRight))
	)

	if opts.Overlay {
		overlaySkin := fixTransparency(skin)

		composite(frontHead, extract(overlaySkin, HeadOverlayFront), 0, 0)
		composite(topHead, rotate90(flipHorizontal(extract(overlaySkin, HeadOverlayTop))), 0, 0)
		composite(rightHead, extract(overlaySkin, HeadOverlayRight), 0, 0)
	}

	// Front Head
	compositeTransform(output, scale(frontHead, opts.Scale), frontMatrix, 8*scaleDouble, 12*scaleDouble)

	// Top Head
	compositeTransform(output, scale(topHead, opts.Scale), plantMatrix, 4*scaleDouble, -4*scaleDouble)

	// Right Head
	compositeTransform(output, scale(rightHead, opts.Scale), sideMatrix, 0, 4*scaleDouble)

	if opts.Square {
		return squareAndCenter(output)
	}

	return output
}