One of the things we wanted to achieve in Grapple was to have a very non-intrusive HUD with minimal, if any, UI (we did have to make some exceptions). With that said, we needed a way to show players where lantern thieves were in the environment.
Within the game’s fiction, we had talked about the power lanterns giving off a kind of gaseous material or vapor of some sort. I took that idea and made a particle out of it. The idea was that the sparkly blue gas would rise into the air, high enough for the player to see, and the player could follow the trail down to find the lantern thief.
A few weeks later, I made another effect to potentially be used for the same purpose. I made a giant pillar of light that would emanate from the lantern thieves into the sky for players to see. I included several parameters in the beam’s material, such as tiling, panning speed, and color so that we could have easy control over the look of the beams.
After considering both options, the team decided on the beams of light. More people liked how they looked, and they were less expensive (since they were just single planes rather than particles).
Once that decision was made, I created two UDK actors in UnrealScript to make it even easier to use and control the beams of light. One actor was simply a plane with the material assigned. This allowed us to drag it into the scene already made (rather than having to recreate planes and reassign the material), and it could be spawned, controlled, and destroyed via code. The second actor housed all of the different parameters in the material plus an XYZ scale for the plane. Changes made in this actor would affect all instances of the beams of light in the game at once, allowing us to quickly and easily globally affect the look of the beams.