//BackProjectGray computes back projection of img
// in Gray16 by performing an addition
// of backprojection by line.
// 16Gray avoids white noise.
func BackProjectGray(img image.Gray) (*image.Gray16, error) {
size := img.Bounds().Size()
width := size.Y
nbProj := size.X
step := 180.0 / float64(nbProj)
out := image.NewGray16(image.Rect(0, 0, width, width))
for X := 0; X < nbProj; X++ {
//Extract a 1D-projection (one row Y of sinogram)
line := img.SubImage(image.Rect(X, 0, X+1, width)).(*image.Gray)
// 3- Do the backprojection and rotate accordingly
wideLine := resize.Resize(uint(width), uint(width), line, resize.Lanczos3).(*image.Gray)
θ := manipulator.Rad(float64(X)*step) + math.Pi/2
rotatedWideLine := image.NewGray(image.Rect(0, 0, width, width))
err := graphics.Rotate(rotatedWideLine, wideLine, &graphics.RotateOptions{Angle: θ})
if err != nil {
return out, err
}
// 4- Add the rotated backprojection in the output image
for x := 0; x < width; x++ {
for y := 0; y < width; y++ {
point := uint16(out.At(x, y).(color.Gray16).Y) + uint16(rotatedWideLine.At(x, y).(color.Gray).Y)
out.Set(x, y, color.Gray16{uint16(point)})
}
}
}
return out, nil
}
func (g *generator) buildTerrain(mpath minecraft.Path, level *level, terrain, biomes, plants *image.Paletted, height, water *image.Gray, c chan paint) error {
b := terrain.Bounds()
proceed := make(chan uint8, 10)
errChan := make(chan error, 1)
go func() {
defer close(proceed)
cc := newCache(g.Terrain.Blocks)
for j := 0; j < b.Max.Y; j += 16 {
chunkZ := int32(j >> 4)
for i := 0; i < b.Max.X; i += 16 {
chunkX := int32(i >> 4)
h := int32(meanHeight(height.SubImage(image.Rect(i, j, i+16, j+16)).(*image.Gray)))
wh := int32(meanHeight(water.SubImage(image.Rect(i, j, i+16, j+16)).(*image.Gray)))
var t uint8
if wh >= h<<1 { // more water than land...
c <- paint{
color.RGBA{0, 0, 255, 255},
chunkX, chunkZ,
}
t = uint8(len(g.Terrain.Blocks) - 1)
h = wh
} else {
t = modeTerrain(terrain.SubImage(image.Rect(i, j, i+16, j+16)).(*image.Paletted), len(g.Terrain.Palette))
c <- paint{
g.Terrain.Palette[t],
chunkX, chunkZ,
}
}
if err := mpath.SetChunk(cc.getFromCache(chunkX, chunkZ, t, h)); err != nil {
errChan <- err
return
}
proceed <- t
}
}
}()
ts := make([]uint8, 0, 1024)
for i := 0; i < (b.Max.X>>4)+2; i++ {
ts = append(ts, <-proceed) // get far enough ahead so all chunks are surrounded before shaping, to get correct lighting
}
select {
case err := <-errChan:
return err
default:
}
for j := int32(0); j < int32(b.Max.Y); j += 16 {
chunkZ := j >> 4
for i := int32(0); i < int32(b.Max.X); i += 16 {
chunkX := i >> 4
var totalHeight int32
ot := ts[0]
ts = ts[1:]
oy, _ := level.GetHeight(i, j)
for x := i; x < i+16; x++ {
for z := j; z < j+16; z++ {
if biomes != nil {
level.SetBiome(x, z, g.Biomes.Values[biomes.ColorIndexAt(int(x), int(z))])
}
h := int32(height.GrayAt(int(x), int(z)).Y)
totalHeight += h
wl := int32(water.GrayAt(int(x), int(z)).Y)
y := oy
if h > y {
y = h
}
if wl > y {
y = wl
}
for ; y > h && y > wl; y-- {
level.SetBlock(x, y, z, minecraft.Block{})
}
if plants != nil {
p := g.Plants.Blocks[plants.ColorIndexAt(int(x), int(z))]
py := int32(1)
for ; py <= int32(p.Level); py++ {
level.SetBlock(x, y+py, z, p.Base)
}
level.SetBlock(x, y+py, z, p.Top)
}
for ; y > h; y-- {
level.SetBlock(x, y, z, minecraft.Block{ID: 9})
}
t := terrain.ColorIndexAt(int(x), int(z))
tb := g.Terrain.Blocks[t]
for ; y > h-int32(tb.Level); y-- {
level.SetBlock(x, y, z, tb.Top)
}
if t != ot {
h = 0
} else {
h = oy
}
for ; y >= h; y-- {
level.SetBlock(x, y, z, tb.Base)
}
}
}
c <- paint{
color.Alpha{uint8(totalHeight >> 8)},
chunkX, chunkZ,
}
select {
case p, ok := <-proceed:
if ok {
ts = append(ts, p)
}
case err := <-errChan:
return err
}
}
}
return nil
}
func blobAt(x, y int, img *image.Gray, vis []bool) *Blob {
if img.GrayAt(x, y) == white {
return nil
}
width := img.Bounds().Max.X
height := img.Bounds().Max.Y
r := image.Rect(x, y, x, y)
q := newQueue()
q.q(point{x, y})
for q.length != 0 {
p := q.dq()
if vis[p.x+width*p.y] {
continue
}
vis[p.x+width*p.y] = true
if p.x > r.Max.X {
r.Max.X = p.x
}
if p.x < r.Min.X {
r.Min.X = p.x
}
if p.y > r.Max.Y {
r.Max.Y = p.y
}
if p.y < r.Min.Y {
r.Min.Y = p.y
}
// Up
if p.y-1 >= 0 {
if !vis[p.x+(p.y-1)*width] && img.GrayAt(p.x, p.y-1) == black {
q.q(point{p.x, p.y - 1})
}
}
// Right
if p.x+1 < width {
if !vis[p.x+1+p.y*width] && img.GrayAt(p.x+1, p.y) == black {
q.q(point{p.x + 1, p.y})
}
}
// Down
if p.y+1 < height {
if !vis[p.x+(p.y+1)*width] && img.GrayAt(p.x, p.y+1) == black {
q.q(point{p.x, p.y + 1})
}
}
// Left
if p.x-1 >= 0 {
if !vis[p.x-1+p.y*width] && img.GrayAt(p.x-1, p.y) == black {
q.q(point{p.x - 1, p.y})
}
}
}
r.Max.Y += 1
r.Max.X += 1
return &Blob{Bounds: r, Img: img.SubImage(r)}
}