How can I make the mouse hit point location vector variables be rounded to 0.5?

Question

I want to spawn actors on the mouse location, but I need them to be spawned on rounded to 0.5 x and y coordinates.

I tried multiplying by 2, rounding and dividing by 2, but it doesn't seem to work.

This is a screenshot of my BP. BluePrint

I expect my actors to be spawned only on rounded to 0.5 coordinates, but instead they spawn on any coordinates.

Yes, I am trying to spawn them on a grid, but aren't they already spawning on the default grid? — ynotxx, Jul 15 '19 at 15:03
When i say grid, i mean a fixed positions and snapping the actors to those positions or grid points. Eg: snap the actor to the closest 100th grid point. And that would be a grid system with 100 units between point. — Playdome.io, Jul 15 '19 at 15:27
Yes, that is exactly what I am trying to do. I did it in Unity, but I really have a difficulty getting used to the way Blue Prints work. — ynotxx, Jul 15 '19 at 15:43
I've posted an answer, you mixed up multiply and divide order — Playdome.io, Jul 15 '19 at 15:53

Playdome.io · Accepted Answer · 2019-07-15T16:14:57.480

To snap a vector to a uniform grid you should use the following formula:

GridPoint = Floor(Point / GridSize) * GridSze;

Where GridSize is a scalar and Point is your input. GridPoint is your output.

It's pretty easy to do with blueprints and the built in math library functions.

Basically just divide your position vector with the prefered grid size (Float) and round/floor it. Then multiply with the grid size and you have your position snapped to the nearest grid point.

UE4 Blueprint example:

UE4 C++

    // Define Grid Size
    float GridSize = 100.0f;

    // Get Actor Position
    FVector Position = GetActorLocation();

    // Calculate Grid Position
    FVector TmpPosition = FVector(Position / GridSize);
    FVector GridPoint = FVector(FMath::RoundHalfToZero(TmpPosition.X),FMath::RoundHalfToZero(TmpPosition.Y), FMath::RoundHalfToZero(TmpPosition.Z)) * GridSize;
    SetActorLocation(GridPoint);

How can I make the mouse hit point location vector variables be rounded to 0.5?

1 Answers1