Tooling

Tools/Terrain/internal/field/datamap.go

@@ -20,7 +20,8 @@ import (
 type DataMapOptions struct {
 	// Sea marks cells to render as flat water rather than data. Optional.
 	Sea []bool
-	// Size is the output side in pixels; the field is point-sampled down to it.
+	// Size is the output width in pixels; the field is point-sampled down to it and the height follows the
+	// field's own aspect.
 	Size int
 	// Log renders log10 of the value, for anything with a heavy tail — drainage area spans seven decades and
 	// is unreadable linearly.
@@ -64,9 +65,10 @@ func WriteDataMap(path string, f *Field, opt DataMapOptions) error {
 		span = 1
 	}
 
-	img := image.NewRGBA(image.Rect(0, 0, size, size))
-	for y := 0; y < size; y++ {
-		sy := y * f.H / size
+	sizeH := aspectH(f, size)
+	img := image.NewRGBA(image.Rect(0, 0, size, sizeH))
+	for y := 0; y < sizeH; y++ {
+		sy := y * f.H / sizeH
 		for x := 0; x < size; x++ {
 			sx := x * f.W / size
 			i := sy*f.W + sx
@@ -123,9 +125,13 @@ func WriteBasinMap(path string, w, h int, receiver []int32, sea []bool, size int
 		}
 	}
 
-	img := image.NewRGBA(image.Rect(0, 0, size, size))
-	for y := 0; y < size; y++ {
-		sy := y * h / size
+	sizeH := int(float64(size)*float64(h)/float64(w) + 0.5)
+	if sizeH < 1 {
+		sizeH = 1
+	}
+	img := image.NewRGBA(image.Rect(0, 0, size, sizeH))
+	for y := 0; y < sizeH; y++ {
+		sy := y * h / sizeH
 		for x := 0; x < size; x++ {
 			sx := x * w / size
 			i := sy*w + sx
@@ -191,6 +197,10 @@ func sampleStops(s [][3]float64, t float64) [3]float64 {
 	return [3]float64{a[0] + (b[0]-a[0])*u, a[1] + (b[1]-a[1])*u, a[2] + (b[2]-a[2])*u}
 }
 
+// HSV is exported because the region map colours its regions the same way the basin map colours its basins:
+// a hash of the id straight to a hue, so neighbours get unrelated colours and a boundary is a hard edge.
+func HSV(hue, sat, val float64) [3]float64 { return hsv(hue, sat, val) }
+
 func hsv(hue, sat, val float64) [3]float64 {
 	h6 := hue * 6
 	i := int(h6)