Implement basic pathfinding

bot/path/blocks.go

@@ -0,0 +1,49 @@
+package path
+
+import (
+	"github.com/Tnze/go-mc/bot/world"
+	"github.com/Tnze/go-mc/data/block"
+)
+
+var (
+	safeStepBlocks = make(map[world.BlockStatus]struct{}, 1024)
+	blocks         = []block.Block{
+		block.Stone,
+		block.Granite,
+		block.PolishedGranite,
+		block.Diorite,
+		block.PolishedDiorite,
+		block.Andesite,
+		block.PolishedAndesite,
+		block.GrassBlock,
+		block.Dirt,
+		block.CoarseDirt,
+		block.Cobblestone,
+		block.OakPlanks,
+		block.SprucePlanks,
+		block.BirchPlanks,
+		block.JunglePlanks,
+		block.AcaciaPlanks,
+		block.DarkOakPlanks,
+		block.Bedrock,
+		block.GoldOre,
+		block.IronOre,
+		block.CoalOre,
+		block.Glass,
+		block.LapisOre,
+		block.Sandstone,
+		block.RedstoneOre,
+	}
+)
+
+func init() {
+	for _, b := range blocks {
+		if b.MinStateID == b.MaxStateID {
+			safeStepBlocks[world.BlockStatus(b.MinStateID)] = struct{}{}
+		} else {
+			for i := b.MinStateID; i <= b.MaxStateID; i++ {
+				safeStepBlocks[world.BlockStatus(i)] = struct{}{}
+			}
+		}
+	}
+}

bot/path/path.go

@@ -0,0 +1,157 @@
+// Package path implements pathfinding.
+package path
+
+import (
+	"github.com/Tnze/go-mc/bot/world"
+	"github.com/Tnze/go-mc/data/block"
+	"github.com/beefsack/go-astar"
+)
+
+type V3 struct {
+	X, Y, Z int
+}
+
+func (v V3) Cost(other V3) float64 {
+	x, y, z := v.X-other.X, v.Y-other.Y, v.Z-other.Z
+	return float64(x*x+z*z) + 1.2*float64(y*y)
+}
+
+// Nav represents a navigation to a position.
+type Nav struct {
+	World       *world.World
+	Start, Dest V3
+}
+
+func (n *Nav) Path() (path []astar.Pather, distance float64, found bool) {
+	return astar.Path(
+		Tile{ // Start point
+			Nav:      n,
+			Movement: Waypoint,
+			Pos:      n.Start,
+		},
+		Tile{ // Destination point
+			Nav:      n,
+			Movement: Waypoint,
+			Pos:      n.Dest,
+		})
+}
+
+// Movement represents a single type of movement in a path.
+type Movement uint8
+
+var allMovements = []Movement{TraverseNorth, TraverseSouth, TraverseEast, TraverseWest}
+
+// Valid movement values.
+const (
+	Waypoint Movement = iota
+	TraverseNorth
+	TraverseSouth
+	TraverseEast
+	TraverseWest
+)
+
+// Tile represents a point in a path. All tiles in a path are adjaceent their
+// preceeding tiles.
+type Tile struct {
+	Nav *Nav
+
+	Movement Movement
+	Pos      V3
+}
+
+func (t Tile) PathNeighborCost(to astar.Pather) float64 {
+	other := to.(Tile)
+	return 1 + other.Movement.BaseCost()
+}
+
+func (t Tile) PathEstimatedCost(to astar.Pather) float64 {
+	other := to.(Tile)
+	cost := t.Pos.Cost(other.Pos)
+	return cost + other.Movement.BaseCost()
+}
+
+func (t Tile) PathNeighbors() []astar.Pather {
+	possibles := make([]astar.Pather, 0, 8)
+
+	if t.Pos == t.Nav.Dest && t.Movement != Waypoint {
+		dupe := t
+		dupe.Movement = Waypoint
+		return []astar.Pather{dupe}
+	}
+
+	for _, m := range allMovements {
+		x, y, z := m.Offset()
+		pos := V3{X: t.Pos.X + x, Y: t.Pos.Y + y, Z: t.Pos.Z + z}
+		if m.Possible(t.Nav, pos.X, pos.Y, pos.Z) {
+			possibles = append(possibles, Tile{
+				Nav:      t.Nav,
+				Movement: m,
+				Pos:      pos,
+			})
+		}
+	}
+
+	// fmt.Printf("%v.Neighbours(): %+v\n", t.Pos, possibles)
+	return possibles
+}
+
+func (m Movement) Possible(nav *Nav, x, y, z int) bool {
+	// fmt.Printf("%s.Possible(%d,%d,%d)\n", m, x, y, z)
+	switch m {
+	case Waypoint, TraverseNorth, TraverseSouth, TraverseEast, TraverseWest:
+		b := nav.World.GetBlockStatus(x, y, z)
+		if _, safe := safeStepBlocks[b]; !safe {
+			return false
+		}
+		above1 := uint32(nav.World.GetBlockStatus(x, y+1, z))
+		above2 := uint32(nav.World.GetBlockStatus(x, y+2, z))
+		return above1 == block.Air.MinStateID && above2 == block.Air.MinStateID
+	default:
+		panic(m)
+	}
+}
+
+func (m Movement) Offset() (x, y, z int) {
+	switch m {
+	case Waypoint:
+		return 0, 0, 0
+	case TraverseNorth:
+		return 0, 0, -1
+	case TraverseSouth:
+		return 0, 0, 1
+	case TraverseEast:
+		return 1, 0, 0
+	case TraverseWest:
+		return -1, 0, 0
+	default:
+		panic(m)
+	}
+}
+
+func (m Movement) BaseCost() float64 {
+	switch m {
+	case Waypoint:
+		return 0
+	case TraverseNorth, TraverseSouth, TraverseEast, TraverseWest:
+		return 1
+	default:
+		panic(m)
+	}
+}
+
+func (m Movement) String() string {
+	switch m {
+	case Waypoint:
+		return "waypoint"
+	case TraverseNorth:
+		return "traverse-north"
+	case TraverseSouth:
+		return "traverse-south"
+	case TraverseEast:
+		return "traverse-east"
+	case TraverseWest:
+		return "traverse-west"
+	default:
+		panic(m)
+	}
+}