Plant launch lerp animation

core/src/mindustry/graphics/g3d/PlanetParams.java

@@ -10,6 +10,10 @@ import mindustry.type.*;
 public class PlanetParams{
     /** Camera direction relative to the planet. Length is determined by zoom. */
     public Vec3 camPos = new Vec3(0f, 0f, 4f);
+    /** If not null, this is the position of the "previous" planet for smooth camera movement. */
+    public @Nullable Vec3 otherCamPos;
+    /** Interpolation value for otherCamPos. */
+    public float otherCamAlpha = 0f;
     /** Camera up vector. */
     public Vec3 camUp = new Vec3(0f, 1f, 0f);
     /** the unit length direction vector of the camera **/

core/src/mindustry/graphics/g3d/PlanetRenderer.java

@@ -69,7 +69,12 @@ public class PlanetRenderer implements Disposable{
 
         cam.resize(w, h);
         params.camPos.setLength((params.planet.radius + params.planet.camRadius) * camLength + (params.zoom-1f) * (params.planet.radius + params.planet.camRadius) * 2);
-        cam.position.set(params.planet.position).add(params.camPos);
+
+        if(params.otherCamPos != null){
+            cam.position.set(params.otherCamPos).lerp(params.planet.position, params.otherCamAlpha).add(params.camPos);
+        }else{
+            cam.position.set(params.planet.position).add(params.camPos);
+        }
         //cam.up.set(params.camUp); //TODO broken
         cam.lookAt(params.planet.position);
         cam.update();