Added Codecs to Easing and EasingGroup

src/main/java/dev/latvian/mods/kmath/util/Easing.java

@@ -1,7 +1,9 @@
 package dev.latvian.mods.kmath.util;
 
+import com.mojang.serialization.Codec;
 import dev.latvian.mods.kmath.KMath;
 import it.unimi.dsi.fastutil.doubles.Double2DoubleFunction;
+import net.minecraft.util.dynamic.Codecs;
 import net.minecraft.util.math.Vec3d;
 
 import java.util.LinkedHashMap;
@@ -12,6 +14,7 @@
  */
 public final class Easing {
 	public static final Map<String, Easing> FUNCTIONS = new LinkedHashMap<>();
+	public static final Codec<Easing> CODEC = Codecs.idChecked(Easing::toString, FUNCTIONS::get);
 
 	public static Easing add(String id, Double2DoubleFunction function) {
 		var easing = add(id, function);
@@ -99,4 +102,9 @@ public Vec3d lerp(double t, Vec3d a, Vec3d b) {
 		var e = function.get(t);
 		return new Vec3d(KMath.lerp(e, a.x, b.x), KMath.lerp(e, a.y, b.y), KMath.lerp(e, a.z, b.z));
 	}
+
+	@Override
+	public String toString() {
+		return id;
+	}
 }

src/main/java/dev/latvian/mods/kmath/util/EasingGroup.java

@@ -1,10 +1,14 @@
 package dev.latvian.mods.kmath.util;
 
+import com.mojang.serialization.Codec;
+import net.minecraft.util.dynamic.Codecs;
+
 import java.util.LinkedHashMap;
 import java.util.Map;
 
 public class EasingGroup {
 	public static final Map<String, EasingGroup> GROUPS = new LinkedHashMap<>();
+	public static final Codec<EasingGroup> CODEC = Codecs.idChecked(EasingGroup::toString, GROUPS::get);
 
 	public static EasingGroup add(String id, Easing in, Easing out, Easing inOut) {
 		var group = new EasingGroup(id, in, out, inOut);
@@ -42,4 +46,9 @@ private EasingGroup(String id, Easing in, Easing out, Easing inOut) {
 		this.out = out;
 		this.inOut = inOut;
 	}
+
+	@Override
+	public String toString() {
+		return id;
+	}
 }