[orx-shapes] Add Path3D.projectToContour, Segment3D.projectToContour

orx-shapes/src/commonMain/kotlin/path3d/Path3DExtensions.kt

@@ -0,0 +1,70 @@
+package org.openrndr.extra.shapes.path3d
+
+import org.openrndr.math.Matrix44
+import org.openrndr.math.Vector2
+import org.openrndr.math.Vector3
+import org.openrndr.shape.*
+
+private val Segment2D.vertices: List<Vector2>
+    get() {
+        return when (type) {
+            SegmentType.LINEAR -> listOf(start, end)
+            SegmentType.QUADRATIC -> listOf(start, control[0], end)
+            SegmentType.CUBIC -> listOf(start, control[0], control[1], end)
+        }
+    }
+
+/**
+ * Projects [Path3D] to [ShapeContour]
+ * @param projection The projection matrix to use
+ * @param view The view matrix to use
+ * @param width The viewport width
+ * @param height The viewport height
+ * @since orx 0.4.5
+ */
+
+fun Path3D.projectToContour(projection: Matrix44, view: Matrix44, width: Int, height: Int): ShapeContour {
+    val ps = segments.map { it.projectToSegment2D(projection, view, width, height) }
+    val ok = (ps.asSequence().flatMap { it.vertices }.all { it.x == it.x && it.y == it.y })
+
+    if (ok)
+        return ShapeContour(ps, closed)
+    else
+        return ShapeContour.EMPTY
+}
+
+
+/**
+ * Projects [Segment3D] to [Segment2D]
+ * @param projection The projection matrix to use
+ * @param view The view matrix to use
+ * @param width The viewport width
+ * @param height The viewport height
+ * @since orx 0.4.5
+ */
+
+fun Segment3D.projectToSegment2D(projection: Matrix44, view: Matrix44, width: Int, height: Int): Segment2D {
+    fun Vector3.project(): Vector2 {
+        val p3 = org.openrndr.math.transforms.project(this, projection, view, width, height)
+        return p3.xy
+    }
+
+    return when (control.size) {
+        0 -> Segment2D(start.project(), end.project())
+        1 -> Segment2D(start.project(), control[0].project(), end.project())
+        2 -> Segment2D(start.project(), control[0].project(), control[1].project(), end.project())
+        else -> error("not supported")
+    }
+}
+
+/**
+ * Convert [ShapeContour] to [Path3D]
+ * @since orx 0.4.5
+ */
+fun ShapeContour.toPath3D(): Path3D = Path3D.fromSegments(segments.map { it.toSegment3D() }, closed)
+
+/**
+ * Convert [Segment2D to [Segment3D]
+ * @since orx 0.4.5
+ */
+fun Segment2D.toSegment3D(): Segment3D = Segment3D(start.xy0, control.map { c -> c.xy0 }, end.xy0)

orx-shapes/src/jvmDemo/kotlin/path3d/DemoPath3DProjection.kt

@@ -0,0 +1,41 @@
+package path3d
+
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+import org.openrndr.draw.LineJoin
+import org.openrndr.extra.camera.Orbital
+import org.openrndr.extra.noise.uniformRing
+import org.openrndr.extra.shapes.path3d.projectToContour
+import org.openrndr.math.Vector3
+import org.openrndr.shape.path3D
+
+fun main() {
+    application {
+        configure {
+            width = 720
+            height = 720
+        }
+        program {
+            val path = path3D {
+                var p = Vector3(1.0, 0.0, 0.0)
+                moveTo(p * 6.0)
+                for (i in 0 until 400) {
+                    p += Vector3.uniformRing(0.2, 0.5)
+                    p = p.normalized
+                    arcTo(5.0, cursor.atan2(p * 6.0), false, false, p * 6.0)
+                }
+            }
+            extend(Orbital())
+            extend {
+                drawer.stroke = ColorRGBa.PINK
+                drawer.path(path)
+                val c = path.projectToContour(drawer.projection, drawer.view, width, height)
+                drawer.defaults()
+                drawer.stroke = ColorRGBa.WHITE
+                drawer.lineJoin = LineJoin.ROUND
+                drawer.strokeWeight = 2.0
+                drawer.contour(c)
+            }
+        }
+    }
+}