up3

server/block/model/fence.go

@@ -0,0 +1,75 @@
+package model
+
+import (
+	"github.com/df-mc/dragonfly/server/block/cube"
+	"github.com/df-mc/dragonfly/server/world"
+)
+
+// Fence is a model used by fences of any type. It can attach to blocks with solid faces and other fences of the same
+// type and has a model height just slightly over 1.
+type Fence struct {
+	// Wood specifies if the Fence is made from wood. This field is used to check if two fences are able to attach to
+	// each other.
+	Wood bool
+}
+
+const (
+	fenceHeight = 1.5
+	fenceInset  = 0.375
+)
+
+// BBox returns multiple physics.BBox depending on how many connections it has with the surrounding blocks.
+func (f Fence) BBox(pos cube.Pos, s world.BlockSource) []cube.BBox {
+	boxes := make([]cube.BBox, 0, 2)
+
+	connectWest, connectEast := f.checkConnection(pos, cube.FaceWest, s), f.checkConnection(pos, cube.FaceEast, s)
+	connectNorth, connectSouth := f.checkConnection(pos, cube.FaceNorth, s), f.checkConnection(pos, cube.FaceSouth, s)
+
+	// Check if we have any connections on the Z axis
+	if connectWest || connectEast {
+		sideBox := cube.Box(0, 0, 0, 1, fenceHeight, 1).Stretch(cube.Z, -fenceInset)
+		if connectWest {
+			boxes = append(boxes, sideBox.ExtendTowards(cube.FaceEast, -fenceInset))
+		}
+		if connectEast {
+			boxes = append(boxes, sideBox.ExtendTowards(cube.FaceWest, -fenceInset))
+		}
+	}
+
+	// Check if we have any connections on the X axis
+	if connectNorth || connectSouth {
+		sideBox := cube.Box(0, 0, 0, 1, fenceHeight, 1).Stretch(cube.X, -fenceInset)
+		if connectNorth {
+			boxes = append(boxes, sideBox.ExtendTowards(cube.FaceSouth, -fenceInset))
+		}
+		if connectSouth {
+			boxes = append(boxes, sideBox.ExtendTowards(cube.FaceNorth, -fenceInset))
+		}
+	}
+
+	// If no connections, create a center post box
+	if len(boxes) == 0 {
+		boxes = append(boxes, cube.Box(fenceInset, 0, fenceInset, 1-fenceInset, fenceHeight, 1-fenceInset))
+	}
+
+	return boxes
+}
+
+// FaceSolid returns true if the face is cube.FaceDown or cube.FaceUp.
+func (f Fence) FaceSolid(_ cube.Pos, face cube.Face, _ world.BlockSource) bool {
+	return face == cube.FaceDown || face == cube.FaceUp
+}
+
+// checkConnection checks if the block at the given position and face has a connection to the current fence block.
+func (f Fence) checkConnection(pos cube.Pos, face cube.Face, src world.BlockSource) bool {
+	sidePos := pos.Side(face)
+	sideBlock := src.Block(sidePos)
+	if fence, ok := sideBlock.Model().(Fence); ok && fence.Wood == f.Wood {
+		return true
+	}
+	if sideBlock.Model().FaceSolid(sidePos, face.Opposite(), src) {
+		return true
+	}
+	_, ok := sideBlock.Model().(FenceGate)
+	return ok
+}