Is my ray casting / line tracing wrong?

Development Programming & Scripting C++
1

Hello, it’s me again.




		FCollisionQueryParams Params;
		// Ignore the player's pawn

		// The hit result gets populated by the line trace
		FHitResult Hit;

		// Raycast out from the camera, only collide with pawns (they are on the ECC_Pawn collision channel)
		FVector Start = thruster->GetComponentLocation();
		FVector End = Start +  (thruster->GetUpVector() * (traceLength*-1));
		bool bHit = GetWorld()->LineTraceSingleByChannel(Hit, Start, End, ECC_Pawn, Params);


		if (bHit)
		{
			// Hit.Actor contains a weak pointer to the Actor that the trace hit
			FVector step1 = Hit.Location - thruster->GetComponentLocation();
			float vectorLength = step1.Size();
			float alpha = vectorLength / traceLength;
			float step2 = FMath::Lerp(hoverForce, 0.0f, alpha);
			FVector downwardForce = Hit.ImpactNormal * step2;
			//StaticMeshComponent->AddForceAtLocation(FVector(0, 0, 1) * hoverForce *(1.0f - (Hit.Distance / traceLength)), thruster->GetComponentLocation());
			StaticMeshComponent->AddForceAtLocation(downwardForce, thruster->GetComponentLocation());
			StaticMeshComponent->SetLinearDamping(inDamping);
			StaticMeshComponent->SetAngularDamping(8.0f);

			compressionRatio = alpha;
			surfaceImpactNormal = Hit.ImpactNormal;
			surfaceImpactPoint = Hit.ImpactPoint;
		}

The problem is my trace length and debug differs.

If you look at the first picture my trace length is going through the ground. No I don’t want that, I want it to touch the ground, and then push me up.

78240-u1.png
Second picture:
I am in mid - air and my trace length (the yellow lines) are way longer.

Untitled2.png
Untitled2.png857×447 252 KB

Have I implemented the ray cast wrong?

2

Isn’t using the ECC_Pawn channel going to make it not hit the floor? It looks like you want to either just use LineTraceSingle, or a different channel

More as an FYI, you can use the actual debug to see what it’s doing, something like:



	static FName TraceTagName = FName(TEXT("MyTraceTag"));
	FCollisionQueryParams CollisionParams(TraceTagName, true, Instigator);;
	GetWorld()->DebugDrawTraceTag = TraceTagName;
        // do the trace GetWorld()->LineTraceSingle...