Friday, December 4, 2015

Unreal Engine Diaries #7

  • While working on the Top Down Stealth Toolkit, I noticed that sometimes the character animations that worked in the PIE mode did not work in the Standalone mode. One of the solutions that worked for me was to connect the 'Event Blueprint Update Animations' in all the child anim BPs to their parent update animation events.
  • To find the angle between two rotator variables, it is better not to use normal subtraction to get the difference as this could give odd results in certain scenarios owing to the fact that the rotator values for actor rotation and world rotation follow the (0,180) & (-180,0) range. For example, when you add two positive values, it could produce a negative output and vice versa. In order to work around this situation, the 'Delta (Rotator)' node can be used to get the absolute angular difference between the two rotators.
  • When working on Top Down games, the 'Orient rotation to movement' parameter in the character movement component of the player character can be unticked to have it face the direction of mouse cursor instead of the movement direction.
  • The following method can be used to get the dimensions of a landscape actor:
    1. First create a reference to the landscape actor either through the level blueprint or using the 'Get All Actors of Class' function.
    2. Get the landscape actor reference and then use 'Get Actor Bounds' function to get the box extent.
    3. Break the box extent vector into it's float values representing the magnitude on each axis and then multiply each by 2 in order to get the length, width and height of the landscape actor.
  • In the default First Person template, if we do a line trace towards the world space equivalent of the center of the screen, it could be seen that the impact location of the trace and the crosshair location on the screen are offset by a certain amount. This is because the logic used to draw the crosshair on the screen from the HUD class does not take the texture size of the crosshair into account during calculations. To rectify this issue and display the crosshair at the true center, we can subtract both x and y location by half the corresponding dimensions of the texture used for crosshair, before plugging it into the draw texture function. In the default case, that would mean subtracting both by 8 units. Doing so should make sure that the trace hit locations match with the crosshair location.
    [ExtendedFirstPersonTemplate_PreciseAim Project Files link:]