How to make a ground targeting system for any terrain type

Development Programming & Scripting Blueprint
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1

I am trying to make an actor that can place objects in the world some distance in front of him. I always want the object to be 1000 units in the horizontal axis in front of the actor but placed on the ground.

Below I have added an image where the green triangle is my actor and the red square is the desired placement of my object.

image
image1139Ă—606 9.17 KB

First, I find a starting point that is 1000 units in front of the actor by getting his forward vector.

The methods I have tried:

  1. Line trace from starting point straight downwards. This works for cases 1, 2 and 4, but doesn’t work for case 3 because the starting point is already below terrain.
  2. Line trace from xy coordinates of starting point but + 999z (higher up). This works for cases 1, 2 and 3, but doesn’t work for case 4 because the ceiling intercepts the trace.
  3. Method 1 for cases 1,2,4 but Line trace from starting point straight upwards used only on case 3. This doesn’t work because the trace start is inside terrain and instantly registers a hit instead of going to the surface. I do not know if it is possible to get the first surface point from inside static meshes.

I am out of ideas how to achieve this behavior regardless of terrain. Any hints and ideas would be appreciated.

2

Easiest approach without knowing all the possible edge cases…

Add 1,000 units to the Z axis Start point. Thus firing forward from an elevated position above the player. At hit/end of trace, trace down n + 1000 units.

This won’t however give you an exact 1,000 units ahead via surface distance…just 1000 units in world space.

3

Another idea:

  1. Trace forward: if no hit, trace down and spawn on hit. If hit…
  2. Loop trace strating Z + n (leys say 50.0) over last end vector and trace down 50.0: if no hit, next loop add 50.0 Z and trace 50.00 down again untril X tries or blocking hit returns true.
  3. When tracing agains planes there is a chance that you will not hit anything on the first loops. So have a bool set to true when it hits something, then when next loop fails to hit, you know last hit was solid ground.

BP is a bit messy but just to get the idea across… hope it helps.
Imgur

SpawnActorsAtDistance

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4

Thanks. This solves the issue.