up3

server/world/chunk/heightmap.go

@@ -0,0 +1,46 @@
+package chunk
+
+import (
+	"math"
+)
+
+// HeightMap represents the height map of a chunk. It holds the y value of all the highest blocks in the chunk
+// that diffuse or obstruct light.
+type HeightMap []int16
+
+// At returns the height map value at a specific column in the chunk.
+func (h HeightMap) At(x, z uint8) int16 {
+	return h[(uint16(x)<<4)|uint16(z)]
+}
+
+// Set changes the height map value at a specific column in the chunk.
+func (h HeightMap) Set(x, z uint8, val int16) {
+	h[(uint16(x)<<4)|uint16(z)] = val
+}
+
+// HighestNeighbour returns the height map value of the highest directly neighbouring column of the x and z values
+// passed.
+func (h HeightMap) HighestNeighbour(x, z uint8) int16 {
+	highest := int16(math.MinInt16)
+	if x != 15 {
+		if val := h.At(x+1, z); val > highest {
+			highest = val
+		}
+	}
+	if x != 0 {
+		if val := h.At(x-1, z); val > highest {
+			highest = val
+		}
+	}
+	if z != 15 {
+		if val := h.At(x, z+1); val > highest {
+			highest = val
+		}
+	}
+	if z != 0 {
+		if val := h.At(x, z-1); val > highest {
+			highest = val
+		}
+	}
+	return highest
+}