Problem with SuggestProjectileVelocity

Development Programming & Scripting
1

I am having problem using SuggestProjectileVelocity.
The output velocity doesn’t seems right to me.
Here is a clip I recorded on what happen https://youtu.be/4GcHQkqHGSM

The AI tank and Player tank has the same AimingComponent on them.
As you can see the projectile lands before the aiming point.
I have this code in my TankAimingComponent.cpp

bool bHaveAimSolution = UGameplayStatics::SuggestProjectileVelocity(
    this,
    OutLaunchVelocity,
    StartLocation,
    HitLocation,
    LaunchSpeed,
    false,
    0,
    0,
    ESuggestProjVelocityTraceOption::DoNotTrace
);

auto AimDirection = OutLaunchVelocity.GetSafeNormal();
MoveBarrelTowards(AimDirection);

void UTankAimingComponent::MoveBarrelTowards(FVector AimDirection) {
	//work-out difference current barrel rotation, and AimDirection
	auto BarrelRotator = Barrel->GetForwardVector().Rotation();
	auto AimAsRotator = AimDirection.Rotation();
	auto DeltaRotator = AimAsRotator - BarrelRotator;

	//1 roll barrel up ,  -1 roll barrel down
	Barrel->Elevate(DeltaRotator.Pitch);
	Turret->Rotate(DeltaRotator.Yaw);
}

After getting OutLaunchVelocity. I use it on my barrel’s Pitch.

I have double checked my StartLocation/HitLocation/LaunchSpeed are at the right value.
And my ProjectileMovement’s blueprint setting on [Projectile Gravity Scale] is on 1.0

Wondering is there any other possible setting I mess up the OutLaunchVelocity value?

Here is my github: https://github.com/pzkwv/04_BattleTank2

Edit: I didn’t put the code in Tank.cpp, it’s actuallly in my TankAimingComponent.cpp

2

Hi, can you text what are you doing with OutLauchVelocity once you have it?

3

Hi MrMcKvarz, I have edited the post. After getting OutLaunchVelocity value. I have used it on my barrel’s Pitch. You can see the new edited code snippet inside of my post.

4

I didn’t get it aiming perfectly either, I thought it was due to barrel rotation restriction. Does your start location and projectile spawn location are the same?

5

Yes, my start location and projectile spawn location is the same.
That’s why I was wondering if it wasn’t c++ code’s problem.

6

um… some how I change the value on [Projectile Gravity Scale] from 1.0 to 0. It acts correctly now. But the tutorial video actually has it on 1.0…

7

I have the same problem :frowning:

8

See this link: Tutorial - Hitting Targets with Arching Projectiles in Unreal Engine - YouTube

Thank me later :slight_smile: