Tooling

Tools/Terrain/internal/fluvial/mfd_bench_test.go

@@ -0,0 +1,27 @@
+package fluvial
+
+import "testing"
+
+// What the two accumulators cost per cell, which is the number a bake's wall clock is spent against. Both are
+// measured on the same surface with the receivers and the stack already built, because those are shared.
+func benchAccumulate(b *testing.B, mfd bool) {
+	const n = 1024
+	h := planarRamp(n, 8.0, 0.1, 22.5)
+	g := NewGrid(n, n, 8.0, nil)
+	g.SetSeed(37125)
+	g.FillDepressions(h, 1e-3)
+	g.ComputeReceivers(h)
+	g.BuildStack()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		if mfd {
+			g.AccumulateMFD(h, 1)
+		} else {
+			g.Accumulate()
+		}
+	}
+	b.ReportMetric(float64(b.Elapsed().Nanoseconds())/float64(b.N)/float64(n*n), "ns/cell")
+}
+
+func BenchmarkAccumulateD8(b *testing.B)  { benchAccumulate(b, false) }
+func BenchmarkAccumulateMFD(b *testing.B) { benchAccumulate(b, true) }