[orx-shapes, orx-mesh-generator] Move frames code from orx-mesh-generator to orx-shapes

orx-shapes/src/commonMain/kotlin/frames/Frames.kt

@@ -0,0 +1,66 @@
+package org.openrndr.extra.shapes.frames
+
+import org.openrndr.math.Matrix44
+import org.openrndr.math.Vector3
+import org.openrndr.math.Vector4
+import org.openrndr.math.transforms.buildTransform
+
+/**
+ * Calculate frames (pose matrices) using parallel transport
+ * @param up0 initial up vector, should not be collinear with `this[1] - this[0]`
+ */
+
+fun List<Vector3>.frames(up0: Vector3): List<Matrix44> {
+    return frames(this, up0 = up0)
+}
+
+fun frames(positions: List<Vector3>, directions: List<Vector3> = emptyList(), up0: Vector3): List<Matrix44> {
+
+    require(up0.squaredLength > 0.0) {
+        "up0 ($up0) has 0 or NaN length"
+    }
+
+    val result = mutableListOf<Matrix44>()
+
+    if (positions.isEmpty()) {
+        return emptyList()
+    }
+
+    if (positions.size == 1) {
+        return listOf(Matrix44.IDENTITY)
+    }
+
+    var up = up0.normalized
+    run {
+        val current = positions[0]
+        val next = positions[1]
+        val forward = (directions.getOrNull(0) ?: (next - current)).normalized
+        val right = (forward cross up).normalized
+        up = ((right cross forward)).normalized
+        result.add(Matrix44.fromColumnVectors(right.xyz0, up.xyz0, forward.xyz0, current.xyz1))
+    }
+
+    for (i in 1 until positions.size - 1) {
+        val prev = positions[i - 1]
+        val current = positions[i]
+        val next = positions[i + 1]
+        val f1 = (next - current).normalized
+        val f0 = (current - prev).normalized
+
+        val forward = (directions.getOrNull(i) ?: (f0 + f1)).normalized
+        require(forward.length > 0.0) { "`forward.length` is zero or NaN in .frames()" }
+        val right = (forward cross up).normalized
+        up = ((right cross forward)).normalized
+
+        require(up.length > 0.0) { "`up.length` is zero or NaN in .frames()" }
+        require(right.length > 0.0) { "`right.length` is zero or NaN in .frames()" }
+
+        val m = buildTransform {
+            translate(current)
+            multiply(Matrix44.fromColumnVectors(right.xyz0, up.xyz0, forward.xyz0, Vector4.UNIT_W))
+        }
+
+        result.add(m)
+    }
+    return result
+}

orx-shapes/src/commonMain/kotlin/frames/Path3DExtensions.kt

@@ -0,0 +1,20 @@
+package org.openrndr.extra.shapes.frames
+
+import org.openrndr.extra.shapes.rectify.RectifiedPath3D
+import org.openrndr.math.Matrix44
+import org.openrndr.math.Vector3
+import org.openrndr.shape.Path3D
+
+fun Path3D.frames(ascendingTs: List<Double>, up0: Vector3, analyticalDirections: Boolean) : List<Matrix44> {
+    val positions = ascendingTs.map { this.position(it) }
+    val directions = if (analyticalDirections) ascendingTs.map { this.direction(it) } else emptyList()
+
+    return frames(positions, directions, up0)
+}
+
+fun RectifiedPath3D.frames(ascendingTs: List<Double>, up0: Vector3, analyticalDirections: Boolean = true) : List<Matrix44> {
+    val positions = ascendingTs.map { this.position(it) }
+    val directions = if (analyticalDirections) ascendingTs.map { this.direction(it) } else emptyList()
+
+    return frames(positions, directions, up0)
+}

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

@@ -92,6 +92,14 @@ abstract class RectifiedPath<T : EuclideanVector<T>>(
         }
     }
 
+    fun direction(t: Double): T {
+        return if (path.empty) {
+            path.infinity
+        } else {
+            path.direction(rectify(safe(t)))
+        }
+    }
+
     abstract fun sub(t0: Double, t1: Double): Path<T>
 
     /**