diff --git a/README.md b/README.md
index 4b8d946..fcecebe 100644
--- a/README.md
+++ b/README.md
@@ -8,10 +8,6 @@
 
 A rewrite of the original CAD package [`sdfx`](https://github.com/deadsy/sdfx) for generating 2D and 3D geometry using [Go](https://go.dev/).
 
- * Objects are modelled with 2d and 3d signed distance functions (SDFs).
- * Objects are defined with Go code.
- * Objects are rendered to an STL file to be viewed and/or 3d printed.
-
 ## Highlights
 * 3d and 2d objects modelled with signed distance functions (SDFs).
 * Minimal and idiomatic API.
diff --git a/render/form3_test.go b/render/form3_test.go
index b91d39b..d668622 100644
--- a/render/form3_test.go
+++ b/render/form3_test.go
@@ -110,7 +110,7 @@ func cylinderToSTL(t testing.TB, filename string) {
 }
 
 func boxToSTL(t testing.TB, filename string) {
-	object := form3.Box(r3.Vec{1, 2, 1}, .3)
+	object := form3.Box(r3.Vec{X: 1, Y: 2, Z: 1}, .3)
 	err := render.CreateSTL(filename, render.NewOctreeRenderer(object, quality))
 	if err != nil {
 		t.Fatal(err)
diff --git a/render/kdrender_test.go b/render/kdrender_test.go
index bc96601..e79f924 100644
--- a/render/kdrender_test.go
+++ b/render/kdrender_test.go
@@ -34,10 +34,10 @@ func TestKDSDF(t *testing.T) {
 	kdf := NewKDSDF(model)
 	t.Log(kdf.Bounds())
 	start := time.Now()
-	outside := kdf.Evaluate(r3.Vec{2, 0, 0}) // evaluate point outside bounds
-	inside := kdf.Evaluate(r3.Vec{0, 0, 0})  // evaluate point inside bounds
+	outside := kdf.Evaluate(r3.Vec{X: 2, Y: 0, Z: 0}) // evaluate point outside bounds
+	inside := kdf.Evaluate(r3.Vec{X: 0, Y: 0, Z: 0})  // evaluate point inside bounds
 
-	surface := kdf.Evaluate(r3.Vec{1, 0, 0}) // evaluate point on surface
+	surface := kdf.Evaluate(r3.Vec{X: 1, Y: 0, Z: 0}) // evaluate point on surface
 
 	t.Logf("outside:%.2g, inside:%.2g, surface:%.2g in %s", outside, inside, surface, time.Since(start))
 	// render.CreateSTL("kd_after.stl", render.NewOctreeRenderer(sdf, quality/6))
@@ -133,7 +133,6 @@ func (k kdTriangles) Len() int { return len(k) }
 func (k kdTriangles) Pivot(d kdtree.Dim) int {
 	p := kdPlane{dim: int(d), triangles: k}
 	return kdtree.Partition(p, kdtree.MedianOfMedians(p))
-	return 0
 }
 
 // Slice returns a slice of the list using zero-based half
@@ -143,8 +142,8 @@ func (k kdTriangles) Slice(start, end int) kdtree.Interface {
 }
 
 func (k kdTriangles) Bounds() *kdtree.Bounding {
-	max := r3.Vec{-math.MaxFloat64, -math.MaxFloat64, -math.MaxFloat64}
-	min := r3.Vec{math.MaxFloat64, math.MaxFloat64, math.MaxFloat64}
+	max := r3.Vec{X: -math.MaxFloat64, Y: -math.MaxFloat64, Z: -math.MaxFloat64}
+	min := r3.Vec{X: math.MaxFloat64, Y: math.MaxFloat64, Z: math.MaxFloat64}
 	for _, tri := range k {
 		tbounds := tri.Bounds()
 		tmin := tbounds.Min.(kdTriangle)