Tagalong menu position

felsiska

I've attached Tagalong script to a canvas with several buttons. advice needed for these 2 issues:

1. canvas sometimes still sinks into other holograms instead of moving in front of hologram. most of the time canvas will slowly emerge to front of hologram when collision is detected. any way to prevent it from sinking or make it hover over other holograms faster?

2. how do I keep the canvas to always stay at the bottom of FOV?

thx

ahillier

@felsiska,
1. Ensure that all of your holograms have colliders. TagAlong's raycast won't detect these objects if they do not have colliders.
2. In 'SimpleTagAlong.cs' you should be able to modify the resulting frustumPlanes object to only cover the lower part of the camera frustum:
frustumPlanes = GeometryUtility.CalculateFrustumPlanes(Camera.main);

timg

Additionally, if you aren't using SimpleTagalong, you can increase HorizontalRayCount and/or VerticalRayCount to increase the likelihood that one of the TagAlong's Raycasts will hit your other hologram(s).

felsiska

@ahillier @timg
i am only using Tagalong as i want it to be in front of all objects. how can i implement the locking of position to bottom of frustum in Tagalong.cs? i'm also not sure how to edit
frustumPlanes = GeometryUtility.CalculateFrustumPlanes(Camera.main); to lock it only to bottom.

thx for previous advices

timg

You'll probably want to implement your own class that derives from Tagalong or SimpleTagalong and in that class, override CalculateTargetPosition. In that method, you should adjust frustumPlanes[frustumTop] by moving it down, thus forcing your tagalong to resolve its targeted position in the lower portion of the frustum. then, call base.CalculateTargetPosition.

I've not tried this myself, but the approach seems sound.

ctsholo

@timg What you mean by moving it down?. Why do all you guys leave everything to suspense .
@timg > @timg said:

In that method, you should adjust frustumPlanes[frustumTop] by moving it down, thus forcing your tagalong to resolve its targeted position in the lower portion of the frustum. then, call base.CalculateTargetPosition.

>

timg

frustumPlanes is filled in by GraphicsUtility.CalculateFrustumPlanes(). By moving it down, I mean to shrink the area Tagalong has to play with by taking the frustomTop plane and moving it down. See the pictures here to help visualize what you are trying to do.

Like I said above, I've note tried this myself, but the approach seems sound. You'll probably need to implement these steps:
1. Find a point on the plane.
2. Calculate a new point along the plane's normal.
3. Use SetNormalAndPosition() to update frustumPlanes[frustumTop].

edit - updated steps that match the code below
1. Find a point in front of the camera
2. Redefine frustumPlanes[frustumTop] with that point and the original normal for the plane

timg

Here's some actual code to get you started...

using UnityEngine;
using HoloToolkit.Unity;

public class MyTagalong : Tagalong
{
    protected override bool CalculateTagalongTargetPosition(Vector3 fromPosition, out Vector3 toPosition)
    {
        // restrict the Tagalong to use the lower-half of the
        // view frustum

        // Find a point in front of the camera
        Vector3 point = Camera.main.transform.position + Camera.main.transform.forward * TagalongDistance;

        // redefine the top plane so it intersects with that point
        frustumPlanes[frustumTop] = new Plane(frustumPlanes[frustumTop].normal, point);

        // call the base implementation to do the work
        return base.CalculateTagalongTargetPosition(fromPosition, out toPosition);
    }
}