From dda653b2cf9b56447517aee3757dc42209bdb2ad Mon Sep 17 00:00:00 2001
From: Edwin Jakobs <edwin@rndr.studio>
Date: Sun, 21 Apr 2024 09:37:35 +0200
Subject: [PATCH] [orx-fcurve] Fix bug in Segment2D.tForX

---
 orx-fcurve/src/commonMain/kotlin/FCurve.kt      | 5 ++++-
 orx-fcurve/src/commonTest/kotlin/TestEFCurve.kt | 8 ++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/orx-fcurve/src/commonMain/kotlin/FCurve.kt b/orx-fcurve/src/commonMain/kotlin/FCurve.kt
index 304282b1..58cffaa6 100644
--- a/orx-fcurve/src/commonMain/kotlin/FCurve.kt
+++ b/orx-fcurve/src/commonMain/kotlin/FCurve.kt
@@ -11,6 +11,9 @@ import kotlin.math.abs
  * Find the (first) t value for a given [x] value
  */
 private fun Segment2D.tForX(x: Double): Double {
+    if (x == start.x) return 0.0
+    if (x == end.x) return 1.0
+
     if (linear) {
         return (x - start.x) / (end.x - start.x)
     } else {
@@ -155,7 +158,7 @@ data class FCurve(val segments: List<Segment2D>) {
         if (segments.isEmpty()) {
             return Pair(0.0, null)
         }
-        if (t < segments.first().start.x) {
+        if (t <= segments.first().start.x) {
             val segment = segments.first()
             return Pair(segment.start.y, segment)
         } else if (t > segments.last().end.x) {
diff --git a/orx-fcurve/src/commonTest/kotlin/TestEFCurve.kt b/orx-fcurve/src/commonTest/kotlin/TestEFCurve.kt
index ce46b794..d318bee6 100644
--- a/orx-fcurve/src/commonTest/kotlin/TestEFCurve.kt
+++ b/orx-fcurve/src/commonTest/kotlin/TestEFCurve.kt
@@ -1,4 +1,5 @@
 import org.openrndr.extra.fcurve.efcurve
+import org.openrndr.extra.fcurve.fcurve
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
@@ -30,4 +31,11 @@ class TestEFCurve {
         assertEquals("M0 L1.0, ${0.0} L1.0, ${1.0}", efcurve("M0 (L1.0, {it})[2]"))
         assertEquals("M0 L1.0, ${0.0} L1.0, ${1.0} L1.0, ${0.0} L1.0, ${1.0} L1.0, ${0.0} L1.0, ${1.0}", efcurve("M0 ((L1.0, {it})[2])[3]"))
     }
+
+    @Test
+    fun testContinuity() {
+        val fc = fcurve("Q1 25% 3 100 Q1 25% 3 0 Q1 25% 3 100 Q1 25% 3 0")
+        val s = fc.sampler()
+        assertEquals(0.0,  s(6.0))
+    }
 }
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