From 8723de8a30dc8d65547ace18c86e61cd5b095cea Mon Sep 17 00:00:00 2001
From: izawartka <59137928+izawartka@users.noreply.github.com>
Date: Thu, 13 Aug 2026 21:27:58 +0200
Subject: [PATCH] Implement switch slope calculation

- Implemented track slope calculation in switch tracks
---
 src/helpers/curveHelper.js         | 19 +++++++++++++++++++
 src/model/switch.js                | 17 ++++++++++++++---
 src/model/tracks/standard-track.js | 12 +++++++++---
 3 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/src/helpers/curveHelper.js b/src/helpers/curveHelper.js
index 4780d22..0c9ed18 100644
--- a/src/helpers/curveHelper.js
+++ b/src/helpers/curveHelper.js
@@ -50,10 +50,29 @@ function transformStart(globalStart, globalRotationDeg, localStart, localRotatio
     };
 }
 
+function calculateSlopesFromQuaternion(rotationQuat, radius, length) {
+    const startTangent = new Vector3(0, 0, 1);
+    const endTangent = radius === 0
+        ? startTangent
+        : Vector3.fromAngleY(-length / radius);
+
+    const worldStart = rotationQuat.rotateVector(startTangent);
+    const worldEnd = rotationQuat.rotateVector(endTangent);
+
+    const startHorizontal = Math.hypot(worldStart.x, worldStart.z);
+    const endHorizontal = Math.hypot(worldEnd.x, worldEnd.z);
+
+    return {
+        startSlope: startHorizontal === 0 ? 0 : (worldStart.y / startHorizontal) * 1000,
+        endSlope: endHorizontal === 0 ? 0 : (worldEnd.y / endHorizontal) * 1000,
+    };
+}
+
 const CurveHelper = {
     calculateCurveEnd,
     calculateCurveEndStandard,
     transformStart,
+    calculateSlopesFromQuaternion
 };
 
 export default CurveHelper;
diff --git a/src/model/switch.js b/src/model/switch.js
index 259316d..57b2c90 100644
--- a/src/model/switch.js
+++ b/src/model/switch.js
@@ -152,7 +152,18 @@ export default class Switch extends SceneryObject {
         }
         const trackId = ids[trackDef.dataIndex][0];
         const connections = this._createTrackConnections(switchDef, trackDef, ids);
-        const { startPos, rotationDeg } = CurveHelper.transformStart(this.pos, this.rot, trackDef.pos, trackDef.rot);
+        const { startPos, rotationQuat, rotationDeg } = CurveHelper.transformStart(
+            this.pos,
+            this.rot,
+            trackDef.pos,
+            trackDef.rot
+        );
+
+        const calculatedSlopes = CurveHelper.calculateSlopesFromQuaternion(
+            rotationQuat,
+            trackDef.radius,
+            trackDef.length
+        );
 
         const track = StandardTrack.createSwitchTrack(
             this,
@@ -162,8 +173,8 @@ export default class Switch extends SceneryObject {
             trackDef.length,
             trackDef.radius,
             connections,
-            trackDef.slope1 ?? 0,
-            trackDef.slope2 ?? 0,
+            calculatedSlopes.startSlope,
+            calculatedSlopes.endSlope,
             trackDef.speedLimit ?? 999
         );
         scenery.addObject(track);
diff --git a/src/model/tracks/standard-track.js b/src/model/tracks/standard-track.js
index e54a63c..22c9570 100644
--- a/src/model/tracks/standard-track.js
+++ b/src/model/tracks/standard-track.js
@@ -25,10 +25,16 @@ export default class StandardTrack extends Track  {
     }
 
     getPointAtDist(dist, fromEnd = TrackConnectionEnd.START) {
-        if (fromEnd === TrackConnectionEnd.END) return this.getPointAtDist(this.len - dist, TrackConnectionEnd.START)
+        if (fromEnd === TrackConnectionEnd.END) {
+            return this.getPointAtDist(this.len - dist, TrackConnectionEnd.START);
+        }
+
         const curveEnd = CurveHelper.calculateCurveEndStandard(this.r, dist).endPos;
-        // TODO: Verify slope logic
-        curveEnd.y += (this.start_slope + this.end_slope) / 2000 * dist;
+
+        if (this.source === TrackSource.STANDARD) {
+            curveEnd.y += (this.start_slope + this.end_slope) / 2000 * dist;
+        }
+
         return this._transformPoint(curveEnd);
     }