reduce roughness of sketch connections

ci/release/changelogs/next.md

@@ -4,6 +4,7 @@
 #### Improvements 🧹
 
 - `dagre` layouts that have a connection where one endpoint is a container is much improved. [#1011](https://github.com/terrastruct/d2/pull/1011)
+- `sketch` draws connections with less roughness, which especially improves look of corner bends in ELK. [#1014](https://github.com/terrastruct/d2/pull/1014)
 
 #### Bugfixes ⛑️
 

d2renderers/d2sketch/sketch.go

@@ -316,7 +316,7 @@ func Paths(r *Runner, shape d2target.Shape, paths []string) (string, error) {
 }
 
 func Connection(r *Runner, connection d2target.Connection, path, attrs string) (string, error) {
-	roughness := 1.0
+	roughness := 0.5
 	js := fmt.Sprintf(`node = rc.path("%s", {roughness: %f, seed: 1});`, path, roughness)
 	paths, err := computeRoughPathData(r, js)
 	if err != nil {

d2renderers/d2sketch/sketch_test.go

@@ -18,6 +18,7 @@ import (
 	"oss.terrastruct.com/util-go/go2"
 
 	"oss.terrastruct.com/d2/d2layouts/d2dagrelayout"
+	"oss.terrastruct.com/d2/d2layouts/d2elklayout"
 	"oss.terrastruct.com/d2/d2lib"
 	"oss.terrastruct.com/d2/d2renderers/d2fonts"
 	"oss.terrastruct.com/d2/d2renderers/d2svg"
@@ -39,6 +40,15 @@ func TestSketch(t *testing.T) {
 			script: `winter.snow -> summer.sun
 		`,
 		},
+		{
+			name:   "elk corners",
+			engine: "elk",
+			script: `a -> b
+b -> c
+a -> c
+c -> a
+		`,
+		},
 		{
 			name: "animated",
 			script: `winter.snow -> summer.sun -> trees -> winter.snow: { style.animated: true }
@@ -1057,6 +1067,7 @@ type testCase struct {
 	themeID int64
 	script  string
 	skip    bool
+	engine  string
 }
 
 func runa(t *testing.T, tcs []testCase) {
@@ -1083,9 +1094,13 @@ func run(t *testing.T, tc testCase) {
 		return
 	}
 
+	layout := d2dagrelayout.DefaultLayout
+	if strings.EqualFold(tc.engine, "elk") {
+		layout = d2elklayout.DefaultLayout
+	}
 	diagram, _, err := d2lib.Compile(ctx, tc.script, &d2lib.CompileOptions{
 		Ruler:      ruler,
-		Layout:     d2dagrelayout.DefaultLayout,
+		Layout:     layout,
 		FontFamily: go2.Pointer(d2fonts.HandDrawn),
 	})
 	if !tassert.Nil(t, err) {