world view ray casting

internal/world/block.go

@@ -23,7 +23,8 @@ type BlockAppearance struct {
 	NotSolid    bool   // Is block not solid, i.e., has no hitbox at all? (this makes the zero value reasonable)
 	Light       int    // The light level it emits, 0 is none
 
-	Hitbox []itype.Boxd // Hitbox, in block-local coordinates; empty slice means a default hitbox of 1x1x1
+	Hitbox  []itype.Boxd // Hitbox, in block-local coordinates; empty slice means a default hitbox of 1x1x1
+	Lookbox []itype.Boxd // Selection hitbox, hit only by the view ray; empty means Hitbox[]
 
 	RenderType BlockRenderType // Rendering type, defaults to OneTexture (zero value)
 
@@ -130,6 +131,9 @@ func GetBlockAppearance(position itype.Vec3i, id, aux int, data itype.Dataset, w
 				SizeX: 1, SizeY: 1, SizeZ: 1,
 			}}
 		}
+		if len(app.Lookbox) == 0 {
+			app.Lookbox = app.Hitbox
+		}
 		return app
 	}
 
@@ -146,6 +150,9 @@ func GetBlockAppearance(position itype.Vec3i, id, aux int, data itype.Dataset, w
 			SizeX: 1, SizeY: 1, SizeZ: 1,
 		}}
 	}
+	if len(app.Lookbox) == 0 {
+		app.Lookbox = app.Hitbox
+	}
 	return app
 }
 
@@ -172,6 +179,16 @@ func (b Block) Appearance(position itype.Vec3i) BlockAppearance {
 			SizeX: 1, SizeY: 1, SizeZ: 1,
 		}}
 	}
+	if len(app.Lookbox) == 0 {
+		if len(app.Hitbox) == 0 {
+			app.Lookbox = []itype.Boxd{{
+				OffX: 0, OffY: 0, OffZ: 0,
+				SizeX: 1, SizeY: 1, SizeZ: 1,
+			}}
+		} else {
+			app.Lookbox = app.Hitbox
+		}
+	}
 	return app
 }
 

internal/world/viewray.go

@@ -0,0 +1,48 @@
+package world
+
+import "edgaru089.ml/go/gl01/internal/util/itype"
+
+// CastViewRay
+func (w *World) CastViewRay(from, dir itype.Vec3d, maxlen float64) (ok bool, blockcoord itype.Vec3i, face itype.Direction, where itype.Vec3d, dist float64) {
+
+	bfrom := from.Floor()
+	bfromdir := itype.Direction(-1)
+	for bfrom.ToFloat64().Addv(0.5, 0.5, 0.5).Add(from.Negative()).Length() < maxlen {
+		for todir := itype.Direction(0); todir < 6; todir++ {
+			if todir == bfromdir {
+				continue
+			}
+
+			bto := bfrom.Add(itype.DirectionVeci[todir])
+			block := w.Block(bto)
+
+			if block.Id != 0 {
+				outbox := itype.Boxd{
+					OffX:  float64(bto[0]),
+					OffY:  float64(bto[1]),
+					OffZ:  float64(bto[2]),
+					SizeX: 1,
+					SizeY: 1,
+					SizeZ: 1,
+				}
+				var outface itype.Direction
+				if ok, outface, _, _ = outbox.IntersectRay(from, dir, maxlen); ok {
+					app := block.Appearance(bto)
+					for _, lb := range app.Lookbox {
+						if ok, face, where, dist = lb.IntersectRay(from, dir, maxlen); ok {
+							blockcoord = bto
+							return
+						}
+					}
+				}
+
+				bfromdir = outface.Opposite()
+				bfrom = bto
+				break
+			}
+		}
+	}
+
+	ok = false
+	return
+}