From e2fa39af086b6733fca6cbed8097dff51cfc0ef1 Mon Sep 17 00:00:00 2001
From: Abe Pazos <abe@hamoid.com>
Date: Sun, 13 Jul 2025 11:59:44 +0200
Subject: [PATCH] [orx-composition] Add test and demo for PR#360

---
 .../src/demo/kotlin/DemoClipping.kt           | 43 ++++++++++++++++
 .../src/commonTest/kotlin/TestComposition.kt  | 51 ++++++++++++++++++-
 2 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 openrndr-demos/src/demo/kotlin/DemoClipping.kt

diff --git a/openrndr-demos/src/demo/kotlin/DemoClipping.kt b/openrndr-demos/src/demo/kotlin/DemoClipping.kt
new file mode 100644
index 00000000..c224aa3b
--- /dev/null
+++ b/openrndr-demos/src/demo/kotlin/DemoClipping.kt
@@ -0,0 +1,43 @@
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+import org.openrndr.extra.composition.ClipMode
+import org.openrndr.extra.composition.composition
+import org.openrndr.extra.composition.drawComposition
+import org.openrndr.math.Vector2
+import org.openrndr.shape.Circle
+import org.openrndr.shape.LineSegment
+import org.openrndr.shape.Shape
+
+fun main() = application {
+    program {
+        val outline = Shape(
+            listOf(
+                Circle(drawer.bounds.center, 70.0).contour.reversed,
+                Circle(drawer.bounds.center, 100.0).contour,
+            )
+        )
+
+        val radius = outline.bounds.dimensions.length / 2
+        val off = outline.bounds.center
+        val num = radius.toInt()
+
+        val svg = drawComposition {
+            lineSegments(List(num) { segNum ->
+                val yNorm = (segNum / (num - 1.0))
+                val x = ((segNum % 2) * 2.0 - 1.0) * radius
+                val y = (yNorm * 2.0 - 1.0) * radius
+                val start = Vector2(-x, y) + off
+                val end = Vector2(x, y) + off
+                LineSegment(start, end)
+            })
+            clipMode = ClipMode.INTERSECT
+            shape(outline)
+        }
+        extend {
+            drawer.clear(ColorRGBa.PINK)
+            drawer.fill = null
+            drawer.shape(outline)
+            drawer.composition(svg)
+        }
+    }
+}
\ No newline at end of file
diff --git a/orx-composition/src/commonTest/kotlin/TestComposition.kt b/orx-composition/src/commonTest/kotlin/TestComposition.kt
index 21ab4391..f22ac170 100644
--- a/orx-composition/src/commonTest/kotlin/TestComposition.kt
+++ b/orx-composition/src/commonTest/kotlin/TestComposition.kt
@@ -1,7 +1,14 @@
 package org.openrndr.extra.composition
 
+import org.openrndr.math.Vector2
+import org.openrndr.shape.Circle
+import org.openrndr.shape.LineSegment
+import org.openrndr.shape.Rectangle
 import org.openrndr.shape.Shape
-import kotlin.test.*
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
 
 class TestComposition {
     val composition = let { _ ->
@@ -35,4 +42,46 @@ class TestComposition {
         assertNull(composition.findImage("outer"))
         assertNull(composition.findImage("shape"))
     }
+}
+
+class TestCompositionIntersections {
+    val bounds = Rectangle(Vector2.ZERO, 640.0, 480.0)
+    val outline = Shape(
+        listOf(
+            Circle(bounds.center, 70.0).contour.reversed,
+            Circle(bounds.center, 100.0).contour,
+        )
+    )
+
+    val radius = outline.bounds.dimensions.length / 2
+    val off = outline.bounds.center
+    val num = radius.toInt()
+
+    @Test
+    fun `use a shape as a mask for line segments`() {
+        // Make sure intersections do not fail randomly, which was fixed in
+        // https://github.com/openrndr/orx/commit/e8f50b3dd153ed82de121e9017cf42f6ea95ac8e
+        val svg = List(100) {
+            drawComposition {
+                lineSegments(List(num) { segNum ->
+                    val yNorm = (segNum / (num - 1.0))
+                    val x = ((segNum % 2) * 2.0 - 1.0) * radius
+                    val y = (yNorm * 2.0 - 1.0) * radius
+                    val start = Vector2(-x, y) + off
+                    val end = Vector2(x, y) + off
+                    LineSegment(start, end)
+                })
+                clipMode = ClipMode.INTERSECT
+                shape(outline)
+            }
+        }
+
+        val shapes = svg[50].findShapes()
+        val dimensions = svg[50].bounds.dimensions
+
+        assertTrue(shapes.isNotEmpty())
+        assertTrue(shapes.first().shape.contours.isNotEmpty())
+        assertTrue(dimensions.x > 0.0)
+        assertTrue(dimensions.y > 0.0)
+    }
 }
\ No newline at end of file