How can i move a Keyframe on an Animation Curve with overwriting the key on the target time?

Question

When i move a key (keyA) on curve, and the target time already has an other key (keyB), keyA stays at the original time. How can i move keyA to overwrite keyB? The docs on AnimationCurve.MoveKey says "This is the desired behaviour for dragging keyframes in a curve editor." But the curve editor does the complete oposite: when i move keyA to a frame with keyB, simply overwrites it. How can i do the same runtime? Do i need to remove keyB manually and insert keyA? Any hints on the best practice...? Thanks! (ps.: I don't understand, why there is not an "overwrite" parameter for MoveKey...)

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Best Answer

Answer by Yword · 3 days ago

Hi yale3d, I think AnimationCurve.MoveKey will not overwrite existing key at the target time, so you need to remove that existing key first before moving the selected key.

Or maybe you can take a look at the following extension method, MoveKeyOverwrite.

 using UnityEngine;
 
 public class TestAnimCurve : MonoBehaviour
 {
     public AnimationCurve curve = new AnimationCurve(
         new Keyframe(0, 0),
         new Keyframe(1, 1));
 
     private void Update()
     {
         if (Input.GetKeyDown(KeyCode.Z))
         {
             // Move key0 to time:1
 
             int selectedKeyIndex = 0;
             Keyframe selectedKey = curve.keys[selectedKeyIndex];
             selectedKey.time = 1;
 
             curve.MoveKeyOverwrite(selectedKeyIndex, selectedKey);
         }
     }
 }
 
 
 public static class AnimationCurveExtensions
 { 
     public static void MoveKeyOverwrite(this AnimationCurve curve, int index, Keyframe key)
     {
         if (curve.keys != null && curve.keys.Length > 0)
         {
             for (int i = 0; i < curve.keys.Length; i++)
             {
                 if (Mathf.Approximately(curve.keys[i].time, key.time))
                 {
                     curve.RemoveKey(i);
                 }
             }
         }
 
         curve.MoveKey(index, key);
     }
 }

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yale3d · 3 days ago 0

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Hello! I came to the same conclusion finally, no easier way to do this, i need to remove the existing key. (My approach wasn't this clean though - very nice, thank you!) What still bothers me a bit is that if i want to achieve the same functionality as in the Curve editor, i need to store the original Curve and rebuild a temporary one with each Drag Event. Which is ok, but i don't really understand, why they stated "This is the desired behaviour for dragging keyframes in a curve editor." Actually, what they did is the oposite of desired behavior, as i see... :) Anyway, thank you for your help, i really appreciate it!

How can i move a Keyframe on an Animation Curve with overwriting the key on the target time?

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