noita-mapcap/bin/stitch/util.go

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// Copyright (c) 2019-2022 David Vogel
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//
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT
package main
import (
"fmt"
"image"
"math"
"os"
"sort"
"github.com/google/hilbert"
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)
// Source: https://gist.github.com/sergiotapia/7882944
func getImageFileDimension(imagePath string) (int, int, error) {
file, err := os.Open(imagePath)
if err != nil {
return 0, 0, fmt.Errorf("can't open file %v: %w", imagePath, err)
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}
defer file.Close()
image, _, err := image.DecodeConfig(file)
if err != nil {
return 0, 0, fmt.Errorf("error decoding config of image file %v: %w", imagePath, err)
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}
return image.Width, image.Height, nil
}
// getImageDifferenceValue returns the average quadratic difference of the (sub)pixels.
// 0 means the images are identical, +inf means that the images don't intersect.
func getImageDifferenceValue(a, b *image.RGBA, offsetA image.Point) float64 {
intersection := a.Bounds().Add(offsetA).Intersect(b.Bounds())
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if intersection.Empty() {
return math.Inf(1)
}
aSub := a.SubImage(intersection.Sub(offsetA)).(*image.RGBA)
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bSub := b.SubImage(intersection).(*image.RGBA)
intersectionWidth := intersection.Dx() * 4
intersectionHeight := intersection.Dy()
var value int64
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for iy := 0; iy < intersectionHeight; iy++ {
aSlice := aSub.Pix[iy*aSub.Stride : iy*aSub.Stride+intersectionWidth]
bSlice := bSub.Pix[iy*bSub.Stride : iy*bSub.Stride+intersectionWidth]
for ix := 0; ix < intersectionWidth; ix += 3 {
diff := int64(aSlice[ix]) - int64(bSlice[ix])
value += diff * diff
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}
}
return float64(value) / float64(intersectionWidth*intersectionHeight)
}
func gridifyRectangle(rect image.Rectangle, gridSize int) (result []image.Rectangle) {
for y := divideFloor(rect.Min.Y, gridSize); y < divideCeil(rect.Max.Y, gridSize); y++ {
for x := divideFloor(rect.Min.X, gridSize); x < divideCeil(rect.Max.X, gridSize); x++ {
tempRect := image.Rect(x*gridSize, y*gridSize, (x+1)*gridSize, (y+1)*gridSize)
intersection := tempRect.Intersect(rect)
if !intersection.Empty() {
result = append(result, intersection)
}
}
}
return
}
func hilbertifyRectangle(rect image.Rectangle, gridSize int) ([]image.Rectangle, error) {
grid := gridifyRectangle(rect, gridSize)
gridX := divideFloor(rect.Min.X, gridSize)
gridY := divideFloor(rect.Min.Y, gridSize)
// Size of the grid in chunks
gridWidth := divideCeil(rect.Max.X, gridSize) - divideFloor(rect.Min.X, gridSize)
gridHeight := divideCeil(rect.Max.Y, gridSize) - divideFloor(rect.Min.Y, gridSize)
s, err := hilbert.NewHilbert(int(math.Pow(2, math.Ceil(math.Log2(math.Max(float64(gridWidth), float64(gridHeight)))))))
if err != nil {
return nil, err
}
sort.Slice(grid, func(i, j int) bool {
// Ignore out of range errors, as they shouldn't happen.
hilbertIndexA, _ := s.MapInverse(grid[i].Min.X/gridSize-gridX, grid[i].Min.Y/gridSize-gridY)
hilbertIndexB, _ := s.MapInverse(grid[j].Min.X/gridSize-gridX, grid[j].Min.Y/gridSize-gridY)
return hilbertIndexA < hilbertIndexB
})
return grid, nil
}
// Integer division that rounds to the next integer towards negative infinity.
func divideFloor(a, b int) int {
temp := a / b
if ((a ^ b) < 0) && (a%b != 0) {
return temp - 1
}
return temp
}
// Integer division that rounds to the next integer towards positive infinity.
func divideCeil(a, b int) int {
temp := a / b
if ((a ^ b) >= 0) && (a%b != 0) {
return temp + 1
}
return temp
}