[orx-shapes] Add RectifiedContour

orx-shapes/src/commonMain/kotlin/rectify/RectifiedContour.kt

@@ -0,0 +1,81 @@
+package org.openrndr.extra.shapes.rectify
+
+import org.openrndr.math.Matrix44
+import org.openrndr.math.Vector2
+import org.openrndr.math.clamp
+import org.openrndr.shape.Segment
+import org.openrndr.shape.ShapeContour
+import kotlin.math.floor
+
+/**
+ * RectifiedContour provides an approximately uniform parameterization for [ShapeContour]
+ */
+class RectifiedContour(val contour: ShapeContour, lengthScale: Double = 1.0, distanceTolerance: Double = 0.5) {
+    val points = contour.equidistantPositionsWithT((contour.length * lengthScale).toInt(), distanceTolerance)
+
+    private fun safe(t: Double): Double {
+        return if (contour.closed) {
+            t.mod(1.0)
+        } else {
+            t.clamp(0.0, 1.0)
+        }
+    }
+
+    /**
+     * computes a rectified t-value for [contour]
+     */
+    fun rectify(t: Double): Double {
+        if (t <= 0.0) {
+            return 0.0
+        }
+        val fi = t * (points.size - 1.0)
+        val fr = fi.mod(1.0)
+        val i0 = fi.toInt()
+        val i1 = i0 + 1
+
+        return if (i0 >= points.size - 1) {
+            1.0
+        } else {
+            (points[i0].second * (1.0 - fr) + points[i1].second * fr)
+        }
+    }
+
+    fun position(t: Double): Vector2 {
+        return contour.position(rectify(safe(t)))
+    }
+
+    fun velocity(t: Double): Vector2 {
+        val (segment, st) = contour.segment(rectify(safe(t)))
+        return contour.segments[segment].direction(st)
+    }
+
+    fun normal(t: Double): Vector2 {
+        return contour.normal(rectify(safe(t)))
+    }
+
+    fun pose(t: Double): Matrix44 {
+        return contour.pose(rectify(safe(t)))
+    }
+
+    fun sub(t0: Double, t1: Double): ShapeContour {
+        return if (contour.closed) {
+            contour.sub(rectify(t0.mod(1.0)) + floor(t0), rectify(t1.mod(1.0)) + floor(t1))
+        } else {
+            contour.sub(rectify(t0), rectify(t1))
+        }
+    }
+}
+
+/** create a rectified contour
+ * @param distanceTolerance distance tolerance to use, 0.5 is the default distance tolerance
+ **/
+fun ShapeContour.rectified(distanceTolerance: Double = 0.5): RectifiedContour {
+    return RectifiedContour(this, distanceTolerance = distanceTolerance)
+}
+
+/**  create a rectified contour
+ *   @param distanceTolerance distance tolerance to use, 0.5 is the default distance tolerance
+ * */
+fun Segment.rectified(distanceTolerance: Double = 0.5): RectifiedContour {
+    return RectifiedContour(this.contour, distanceTolerance = distanceTolerance)
+}