[orx-shapes] Add custom tensions to HobbyCurve and related 2D/3D demos and tests

orx-shapes/src/commonTest/kotlin/TestHobbyCurve.kt

@@ -0,0 +1,19 @@
+import org.openrndr.extra.shapes.hobbycurve.hobbyCurve
+import org.openrndr.shape.Rectangle
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class TestHobbyCurve {
+
+    @Test
+    fun testSymmetric() {
+        val rectangle = Rectangle(0.0, 0.0, 100.0, 100.0).contour
+        val h = rectangle.hobbyCurve()
+        assertTrue(h.closed)
+        assertEquals(4, h.segments.size)
+        assertEquals(-1.0, h.direction(0.25).dot(h.direction(0.75)), 1e-6)
+        assertEquals(-1.0, h.direction(0.125).dot(h.direction(0.625)), 1e-6)
+        assertEquals(-1.0, h.direction(0.375).dot(h.direction(0.875)), 1e-6)
+    }
+}