61 lines
1.5 KiB
Go
61 lines
1.5 KiB
Go
package utils
|
|
|
|
import (
|
|
"image"
|
|
"image/color"
|
|
"image/png"
|
|
"os"
|
|
"unsafe"
|
|
)
|
|
|
|
func Img2rgba(img *image.RGBA) []color.RGBA {
|
|
return unsafe.Slice((*color.RGBA)(unsafe.Pointer(unsafe.SliceData(img.Pix))), len(img.Pix)/4)
|
|
}
|
|
|
|
func loadPng(path string) (*image.RGBA, error) {
|
|
f, err := os.Open(path)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
img, err := png.Decode(f)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return (*image.RGBA)(img.(*image.NRGBA)), nil
|
|
}
|
|
|
|
// LERP is a linear interpolation function
|
|
func LERP(p1, p2, alpha float64) float64 {
|
|
return (1-alpha)*p1 + alpha*p2
|
|
}
|
|
|
|
func blendColorValue(c1, c2, a uint8) uint8 {
|
|
return uint8(LERP(float64(c1), float64(c2), float64(a)/float64(0xff)))
|
|
}
|
|
|
|
func blendAlphaValue(a1, a2 uint8) uint8 {
|
|
return uint8(LERP(float64(a1), float64(0xff), float64(a2)/float64(0xff)))
|
|
}
|
|
|
|
func BlendColors(c1, c2 color.RGBA) (ret color.RGBA) {
|
|
ret.R = blendColorValue(c1.R, c2.R, c2.A)
|
|
ret.G = blendColorValue(c1.G, c2.G, c2.A)
|
|
ret.B = blendColorValue(c1.B, c2.B, c2.A)
|
|
ret.A = blendAlphaValue(c1.A, c2.A)
|
|
return ret
|
|
}
|
|
|
|
// DrawImgScaledPos draws src onto dst at bottomLeft, scaled to size
|
|
func DrawImgScaledPos(dst *image.RGBA, src *image.RGBA, bottomLeft image.Point, sizeScaled int) {
|
|
sbx := src.Bounds().Dx()
|
|
ratio := int(float64(sbx) / float64(sizeScaled))
|
|
|
|
for xOut := bottomLeft.X; xOut < bottomLeft.X+sizeScaled; xOut++ {
|
|
for yOut := bottomLeft.Y; yOut < bottomLeft.Y+sizeScaled; yOut++ {
|
|
xIn := (xOut - bottomLeft.X) * ratio
|
|
yIn := (yOut - bottomLeft.Y) * ratio
|
|
dst.Set(xOut, yOut, src.At(xIn, yIn))
|
|
}
|
|
}
|
|
}
|