Fixed ship facing angle animation (avoid a 360 turn)

src/scripts/game/Tools.ts

@@ -3,6 +3,8 @@ module SpaceTac.Game {
 
     // Generic tools functions
     export class Tools {
+
+        // Copy an object (only a shallow copy of immediate properties)
         static copyObject<T> (object: T): T {
             var objectCopy = <T>{};
 

src/scripts/view/battle/ArenaShip.ts

@@ -76,7 +76,7 @@ module SpaceTac.View {
                 var tween_sprite = this.game.tweens.create(this.sprite);
                 tween_group.to({x: x, y: y});
                 tween_group.start();
-                tween_sprite.to({rotation: facing_angle});
+                Tools.rotationTween(tween_sprite, facing_angle);
                 tween_sprite.start();
             } else {
                 this.x = x;

src/scripts/view/common/Tools.ts

@@ -0,0 +1,39 @@
+module SpaceTac.View {
+    "use strict";
+
+    // Common UI tools functions
+    export class Tools {
+
+        // Constraint an angle in radians the ]-pi;pi] range.
+        static normalizeAngle(angle: number): number {
+            angle = angle % (2 * Math.PI);
+            if (angle <= -Math.PI) {
+                return angle + 2 * Math.PI;
+            } else if (angle >  Math.PI) {
+                return angle - 2 * Math.PI;
+            } else {
+                return angle;
+            }
+        }
+
+        // Interpolate a rotation value
+        //  This will take into account the 2*pi modulo
+        static rotationTween(tween: Phaser.Tween, dest: number, property: string = "rotation"): void {
+            // Immediately change the object's current rotation to be in range (-pi,pi)
+            var value = Tools.normalizeAngle(tween.target[property]);
+            tween.target[property] = value;
+
+            // Update the tween
+            dest = Tools.normalizeAngle(dest);
+            if (value - dest > Math.PI) {
+                dest += 2 * Math.PI;
+            } else if (value - dest < -Math.PI) {
+                dest -= 2 * Math.PI;
+            }
+            console.log(value, dest);
+            var changes: Object = {};
+            changes[property] = dest;
+            tween.to(changes);
+        }
+    }
+}

src/scripts/view/specs/Tools.spec.ts

@@ -0,0 +1,16 @@
+/// <reference path="../../definitions/jasmine.d.ts"/>
+
+module SpaceTac.View.Specs {
+    "use strict";
+
+    describe("Tools", () => {
+        it("normalizes angles", () => {
+            expect(Tools.normalizeAngle(0)).toEqual(0);
+            expect(Tools.normalizeAngle(0.1)).toBeCloseTo(0.1, 0.000001);
+            expect(Tools.normalizeAngle(Math.PI)).toBeCloseTo(Math.PI, 0.000001);
+            expect(Tools.normalizeAngle(Math.PI + 0.5)).toBeCloseTo(-Math.PI + 0.5, 0.000001);
+            expect(Tools.normalizeAngle(-Math.PI)).toBeCloseTo(Math.PI, 0.000001);
+            expect(Tools.normalizeAngle(-Math.PI - 0.5)).toBeCloseTo(Math.PI - 0.5, 0.000001);
+        });
+    });
+}