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https://bitbucket.org/s_l_teichmann/mtsatellite
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Simplified area coverage calculation a great deal.
This commit is contained in:
Sascha L. Teichmann
parent
4b92a6c722
commit
ca634f28ef
126
common/area.go
126
common/area.go
@ -4,7 +4,9 @@
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package common
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import "math"
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import (
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"math"
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)
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type Area struct {
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X1, Z1 int16
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@ -28,79 +30,73 @@ func areasContain(areas []Area, x, z int16) bool {
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return false
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}
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// UncoveredAreas implements a greedy algorithm to figure out
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// recalculate implements a greedy algorithm to figure out
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// a list of disjunct areas of free regions in the domain
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// to the (x, z) block plane.
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// oldAreas are searched and found free areas are appended
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// to newAreas which ist return.
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// This is useful to spatial query only blocks from db
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// that are not below already rendered blocks.
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func UncoveredAreas(r *Renderer, newAreas, oldAreas []Area) []Area {
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func (area Area) recalculate(r *Renderer, nareas []Area) []Area {
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yM := r.yMin
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// Scan old areas.
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for _, oldArea := range oldAreas {
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for z := oldArea.Z1; z <= oldArea.Z2; z++ {
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row := z * int16(r.width)
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for x := oldArea.X1; x <= oldArea.X2; x++ {
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// Uncovered and not in list of new areas?
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if yM[row+x] > math.MinInt32 || areasContain(newAreas, x, z) {
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continue
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}
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area := Area{X1: x, Z1: z, X2: x, Z2: z}
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// Try to extend the area in x and/or z till no further extension is possible.
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for extendDirs := 1 | 2; extendDirs != 0; {
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var xFirst bool
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// Try to extend in the direction with most gain
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// of blocks.
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if area.higher() { // Higher means to win more blocks in x direction.
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xFirst = true
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}
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dirs:
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for i := 0; i < 2; i++ {
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if xFirst {
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// Extension in x possible?
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if extendDirs&1 == 1 {
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nx := area.X2 + 1
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if nx > oldArea.X2 {
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extendDirs &= ^1
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continue
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}
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// Scan line below current area if its fully free.
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for nz := area.Z1; nz <= area.Z2; nz++ {
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if yM[nz*int16(r.width)+nx] > math.MinInt32 || areasContain(newAreas, nx, nz) {
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extendDirs &= ^1
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continue dirs
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}
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}
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// free -> extend
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area.X2 = nx
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}
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} else if extendDirs&2 == 2 {
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// Symmetric case in z direction
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nz := area.Z2 + 1
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if nz > oldArea.Z2 {
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extendDirs &= ^2
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continue
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}
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// Scan line right beside the area if its free.
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row2 := nz * int16(r.width)
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for nx := area.X1; nx <= area.X2; nx++ {
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if yM[row2+nx] > math.MinInt32 || areasContain(newAreas, nx, nz) {
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extendDirs &= ^2
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continue dirs
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}
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}
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area.Z2 = nz
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}
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// Switch to other search direction (x -> z or z -> x)
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xFirst = !xFirst
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}
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}
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// At this point the area is extended to max.
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newAreas = append(newAreas, area)
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const ex = 1
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const ez = 2
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nas := len(nareas)
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for z := area.Z1; z <= area.Z2; z++ {
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row := z * int16(r.width)
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for x := area.X1; x <= area.X2; x++ {
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// Uncovered and not in list of new areas?
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if yM[row+x] > math.MinInt32 || areasContain(nareas[nas:], x, z) {
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continue
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}
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a := Area{X1: x, Z1: z, X2: x, Z2: z}
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// Try to extend the area in x and/or z till no further extension is possible.
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ext:
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for extend := ex | ez; extend != 0; {
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// If we extending in both directions a the current area
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// is higher than wide we gain more block if extend
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// in the x direction first.
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if (extend == ex|ez && a.higher()) || extend&ex == ex { // check x
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nx := a.X2 + 1
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if nx > area.X2 { // reached border of area
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extend &= ^ex
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continue
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}
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// Check column right of the current area if its fully free.
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for nz := a.Z1; nz <= a.Z2; nz++ {
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if yM[nz*int16(r.width)+nx] > math.MinInt32 ||
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areasContain(nareas[nas:], nx, nz) {
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extend &= ^ex
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continue ext
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}
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}
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// free -> extend
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a.X2 = nx
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} else if extend&ez == ez { // check z
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nz := a.Z2 + 1
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if nz > area.Z2 {
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extend &= ^ez
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continue
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}
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// Check line right below the current area if its free.
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row2 := nz * int16(r.width)
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for nx := a.X1; nx <= a.X2; nx++ {
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if yM[row2+nx] > math.MinInt32 ||
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areasContain(nareas[nas:], nx, nz) {
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extend &= ^ez
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continue ext
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}
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}
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// free -> extend
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a.Z2 = nz
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}
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}
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// At this point the area is extended to max.
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nareas = append(nareas, a)
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}
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}
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return newAreas
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return nareas
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}
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@ -103,10 +103,10 @@ func (btc *BaseTileCreator) CreateTile(x, z int16, i, j int) (bool, error) {
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var c1, c2 Coord
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oareas := make([]Area, 0, tileWidth*tileHeight/2)
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nareas := make([]Area, 1, tileWidth*tileHeight/2)
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nareas := make([]Area, 0, tileWidth*tileHeight/2)
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areas := make([]Area, 1, tileWidth*tileHeight/2)
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nareas[0] = Area{
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areas[0] = Area{
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X1: 0, Z1: 0,
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X2: int16(tileWidth) - 1, Z2: int16(tileHeight) - 1}
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@ -118,9 +118,7 @@ func (btc *BaseTileCreator) CreateTile(x, z int16, i, j int) (bool, error) {
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c1.Y = max16(yRange[0], btc.yMin)
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c2.Y = min16(yRange[1], btc.yMax)
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var allCount int
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for _, area := range nareas {
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for _, area := range areas {
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c1.X = area.X1 + x
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c1.Z = area.Z1 + z
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c2.X = area.X2 + x
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@ -131,18 +129,22 @@ func (btc *BaseTileCreator) CreateTile(x, z int16, i, j int) (bool, error) {
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if count, err = btc.client.QueryCuboid(query, btc.drawBlock); err != nil {
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return false, err
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}
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allCount += count
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if err = btc.yOrder.Drain(btc.colors); err != nil {
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log.Printf("WARN: rendering block failed: %s\n", err)
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}
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}
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if allCount > 0 {
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xareas := UncoveredAreas(btc.renderer, oareas, nareas)
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if len(xareas) == 0 {
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break
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// If there where loaded blocks in this area recalculate coverage.
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if count > 0 {
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nareas = area.recalculate(btc.renderer, nareas)
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} else {
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nareas = append(nareas, area)
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}
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nareas, oareas = xareas, nareas[:0]
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}
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if len(nareas) == 0 {
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break
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}
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areas, nareas = nareas, areas[:0]
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}
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path := filepath.Join(btc.baseDir, strconv.Itoa(i), strconv.Itoa(j)+".png")
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