58 lines
1.1 KiB
Go
58 lines
1.1 KiB
Go
|
package main
|
||
|
|
|
||
|
|
import (
|
||
|
|
"image"
|
||
|
|
"image/color"
|
||
|
|
"math"
|
||
|
|
)
|
||
|
|
|
||
|
|
// GenerateBumpMap creates a bump map from a heightmap.
|
||
|
|
func GenerateBumpMap(heightmap *image.RGBA, width, height int, depth float64) *image.RGBA {
|
||
|
|
bumpMap := image.NewRGBA(image.Rect(0, 0, width, height))
|
||
|
|
|
||
|
|
sobelX := [][]int{
|
||
|
|
{-1, 0, 1},
|
||
|
|
{-2, 0, 2},
|
||
|
|
{-1, 0, 1},
|
||
|
|
}
|
||
|
|
|
||
|
|
sobelY := [][]int{
|
||
|
|
{-1, -2, -1},
|
||
|
|
{0, 0, 0},
|
||
|
|
{1, 2, 1},
|
||
|
|
}
|
||
|
|
|
||
|
|
for y := 1; y < height-1; y++ {
|
||
|
|
for x := 1; x < width-1; x++ {
|
||
|
|
var gx, gy float64
|
||
|
|
|
||
|
|
for i := 0; i < 3; i++ {
|
||
|
|
for j := 0; j < 3; j++ {
|
||
|
|
gray, _, _, _ := heightmap.At(x+i-1, y+j-1).RGBA()
|
||
|
|
intensity := float64(gray >> 8)
|
||
|
|
gx += intensity * float64(sobelX[j][i])
|
||
|
|
gy += intensity * float64(sobelY[j][i])
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
nx := gx
|
||
|
|
ny := gy
|
||
|
|
nz := 1.0 / depth
|
||
|
|
|
||
|
|
length := math.Sqrt(nx*nx + ny*ny + nz*nz)
|
||
|
|
if length > 0 {
|
||
|
|
nx /= length
|
||
|
|
ny /= length
|
||
|
|
nz /= length
|
||
|
|
}
|
||
|
|
|
||
|
|
r := uint8((nx + 1.0) * 127.5)
|
||
|
|
g := uint8((ny + 1.0) * 127.5)
|
||
|
|
b := uint8(nz * 255.0)
|
||
|
|
|
||
|
|
bumpMap.Set(x, y, color.RGBA{R: r, G: g, B: b, A: 255})
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return bumpMap
|
||
|
|
}
|