Tooling

Tools/Terrain/internal/thermal/thermal.go

@@ -34,6 +34,12 @@ func Apply(h []float32, w, hgt int, cellM, talus float64, passes int, fixed []bo
 	if passes <= 0 || talus <= 0 {
 		return
 	}
+	// The scratch is the caller's so a pass inside a loop does not allocate a grid every time; it is optional
+	// because every other caller of this package passes one and the one that did not spent its first run in a
+	// panic (slice bounds out of range) rather than in a weather simulation.
+	if cap(scratch) < len(h) {
+		scratch = make([]float32, len(h))
+	}
 	delta := scratch[:len(h)]
 	card := cellM
 	diag := cellM * math.Sqrt2