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Align sight to camera

Agustin Andreucci · 2018-06-16T04:50:30

Hi everyone,I got stuck with my approach to aiming down sights. I've set up my first person arms mesh to be a child of the camera. Added a socket on the right hand of the skeleton to which I attach my weapon and there is a socket in the weapon used to signal the point at which the camera should sit during aiming down sight. When the players aims holding left click what I'm trying to do is to calculate the offset of the sight socket to the root of the FPP Mesh while on the aiming down sights pose and move the camera based on that. I'm using the code attached below. It's Unreal Engine but the problem seemed generic enough to qualify as an algebra one. What I'm doing is obtaining the transformations from the camera to the sight bone. That gives me the sight transform relative to the camera. After that I just negate the translation vector and add it to the first child of the camera. I was expecting to have the sight bone sit at the exact same point as the camera. What happens is that it is almost there but it's not correctly aligned. I believe my math and the general idea is right. Any ideas why this could be failing? Here is how I apply the resulting transform and below how I obtain it. Thank you very much for reading. FVector Translation = DeltaTransform.GetTranslation(); Translation.Z = 165.0f; /*Translation.X += Translation.Y; Translation.Y = Translation.X - Translation.Y; Translation.X = Translation.X - Translation.Y;*/ DeltaTransform *= DefaultMesh1PTransform; DeltaTransform.SetTranslation(Translation); Mesh1PCamOffsetLocationDelta = DeltaTransform.GetTranslation(); Mesh1PCamOffsetRotationDelta = DeltaTransform.GetRotation(); bInterpMesh1PCamOffset = bInterp; UE_LOG(LogTemp, Warning, TEXT("DeltaInverse Location x: %f, y: %f, z: %f"), (DeltaTransform).GetLocation().X, (DeltaTransform).GetLocation().Y, (DeltaTransform).GetLocation().Z); Mesh1P->SetRelativeLocation(DeltaTransform.GetLocation() * -1); UE_LOG(LogTemp, Warning, TEXT("Rotation yaw: %f, pitch: %f, roll: %f"), DeltaTransform.GetRotation().Rotator().Yaw, DeltaTransform.GetRotation().Rotator().Pitch, DeltaTransform.GetRotation().Rotator().Roll); FTransform HandToComponent; HandToComponent.SetIdentity(); FTransform BoneTransform; USkeletalMeshComponent* Mesh1P = CarryingPlayer->Mesh1P; // Get transform to weapon attach socket space HandToComponent *= FirearmMesh->GetSocketTransform(FName("sight_point_socket"), RTS_ParentBoneSpace); HandToComponent *= Mesh1P->GetSocketTransform(Firearm->GetCarrySocket(), RTS_ParentBoneSpace); // Get transform from the right hand bone relative to component (root bone) FName CurrentBoneName = FName("hand_r"); while (CurrentBoneName != NAME_None) { ArmsADSIdleAnimSequence->GetBoneTransform(BoneTransform, Mesh1P->GetBoneIndex(CurrentBoneName), 0.0f, true); HandToComponent *= BoneTransform; CurrentBoneName = Mesh1P->GetParentBone(CurrentBoneName); } return HandToComponent;

Math and Physics Programming LinearAlgebra Unreal PC

Started by Agustin Andreucci April 06, 2018 12:45 AM

11 comments, last by Fulcrum.013 6 years ago

Agustin Andreucci

Author

April 08, 2018 02:56 AM

On 6/4/2018 at 6:51 PM, Scouting Ninja said:

You can offset rotation by using Sin and Cos and you can offset location by making a new vector from the old one with the offset added in. Without the animations I can't tell you the exact amount or formula.

It's easier to change the pose. Unreal was made for this kind of adjustments. If you don't want to use a 3D tool for this you can use a empty and use that to offset the whole rig.

Is this happening because you are using animations from two different animation sets? Because animation re-targeting can be used to quickly fix this.

2

I made it work. With the more mainstream approaches, we would require quite a bit of tweaking and since we are a very small team we can't afford it. The math I posted was correct except for the part in which I set the location and rotation of the Mesh1P to counter the socket's transform.

This way I can use less than ideal animation poses and always have the weapon centered.

Thank you very much for your help and taking time to help me out!

Fulcrum.013

-61

June 16, 2018 04:50 AM

On 4/7/2018 at 12:34 AM, Agustin Andreucci said:

Right now the poses I have are close but slightly rotated and translated.

You need not a just sloth. You need a axe that comes from sight to muzzle-sight and eye point on it. With those markups on model it require just translate and rotate a weapon to match eye point with camera point, and axe that connecting sights with camera direction, then recalulate arms pose using simplified IK. Trick is - forearm with fist and upper arm have equal length. So elbow anytime lies on central normal to line segment that comes from shoulder to center of palm. So it enought to add 2 additional markups on weapon - touch points onto its handles to calculate arms transformation .

#define if(a) if((a) && rand()%100)

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Align sight to camera

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Align sight to camera

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