minor fixes in ActionTintBy.cs

new actions:
ActionFadeBy.cs
ActionTintTo.cs

src/ActionsInterval/ActionFadeBy.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using UnityEngine;
+
+class ActionFadeBy : ActionInterval
+{
+    public float delta;
+
+    public ActionFadeBy(float tgtDelta, float tgtDuration)
+        : base(tgtDuration)
+    {
+        delta = tgtDelta;
+    }
+
+    public override Action clone()
+    {
+        return new ActionFadeBy(delta, duration);
+    }
+
+    public override Action reverse()
+    {
+        return new ActionFadeBy(-delta, duration);
+    }
+
+    public override void start()
+    {
+        base.start();
+    }
+
+    public override void stepInterval(float dt)
+    {
+        float d = dt / duration;
+        Color tgtColor = target.gameObject.renderer.material.color;
+        tgtColor[3] += delta * d;
+        target.gameObject.renderer.material.color = tgtColor;
+    }
+}

src/ActionsInterval/ActionTintBy.cs

@@ -13,6 +13,11 @@ class ActionTintBy : ActionInterval
         color = tgtColor * coeff;
     }
 
+    public ActionTintBy(Vector3 tgtColor, float tgtDuration)
+        : this(new Vector4(tgtColor.x, tgtColor.y, tgtColor.z), tgtDuration)
+    {
+    }
+
     public override Action clone()
     {
         return new ActionTintBy(color / coeff, duration);

src/ActionsInterval/ActionTintTo.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using UnityEngine;
+
+class ActionTintTo : ActionInterval
+{
+    public Vector4 color;
+    public Vector4 path;
+    protected const float coeff = 1F / 255F;
+
+    public ActionTintTo(Vector4 tgtColor, float tgtDuration)
+        : base(tgtDuration)
+    {
+        color = tgtColor * coeff;
+        path = Vector4.zero;
+    }
+
+    public ActionTintTo(Vector3 tgtColor, float tgtDuration)
+        : this(new Vector4(tgtColor.x, tgtColor.y, tgtColor.z), tgtDuration)
+    {
+    }
+
+    public override Action clone()
+    {
+        return new ActionTintTo(color / coeff, duration);
+    }
+
+    public override void start()
+    {
+        base.start();
+        Color tgtColor = target.gameObject.renderer.material.color;
+        path[0] = color[0] - tgtColor[0];
+        path[1] = color[1] - tgtColor[1];
+        path[2] = color[2] - tgtColor[2];
+        path[3] = color[3] - tgtColor[3];
+    }
+
+    public override void stepInterval(float dt)
+    {
+        float d = dt / duration;
+        Vector4 tgt = path * d;
+        Color tgtColor = target.gameObject.renderer.material.color;
+        tgtColor[0] += tgt[0];
+        tgtColor[1] += tgt[1];
+        tgtColor[2] += tgt[2];
+        tgtColor[3] += tgt[3];
+        target.gameObject.renderer.material.color = tgtColor;
+    }
+}