Day 3 (11/20/2010)
7. Aiming With The Mouse
Now that I got the camera set up yesterday and played a lot of Vindictus, its time to get back to work. The next step is to get the player to aim towards where their mouse instead of in the direction the player camera is facing. This way movement and aim will be separated and allow for interaction with the world with the freedom of rotation but locking movement to the camera axis. Basically, the player will be controlled like most top-down shooters. Now for this project I am currently using the September build of UDK even though the October build is out as this project is also meant to help some classmates with their project which is currently September based. The reason I bring this up is that the October build of UDK strips out all UIScene functionality completely and everything related to it and in the past the class UIRoot was my primary way of accessing mouse coordinates. This means that for my project to not need a major reworking in the future I would have to find a new way to grab mouse coordinates. Now I looked all over the UDK development code and I could not find a straightforward way to do so. If there is a easier way than the process that I went to that I will go over, please let me know. The way I did it relies on a SWF to store mouse coordinates which then UnrealScript grabs. Its a little odd but it works flawlessly once set up correctly. I figured that if I used ScaleForm to grab mouse coordinates, Epic won't be scrapping ScaleForm any time soon.
The first thing we are going to need to do is to replace the UT HUD with our own ScaleForm based HUD. As fancy as the UT HUD is, I'd rather have my own. Also, I need to create mouse coordinate functionality without relying on the old hud's Canvas to use DeProject, which I'll get into later. For now, I don't need anything fancy in my HUD except a mouse cursor which will indicate where the player is aiming and will also serve as a cursor for UI interaction with HUD menus and things. Time to start up Flash and build me a HUD. I am using a trial version of Flash CS5 at the moment.
With Flash CS5, I have already set up my ScaleForm extension and my ActionScript settings. If you have not dealt with ScaleForm and Flash before, I strongly encourage checking out my ScaleForm series here. With my new flash document open, I went ahead and drew myself a cursor with the flash tools, and this is what I came up with:
