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Archives for March 2016

Reloading a multi-scene scene at runtime in Unity (for debugging)

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Using Unity 5.3’s new Scene Manager can be quite challenging. There’s some basic stuff that’s missing. One of these is the ability to reload the current additive scene.

Here’s my quick hack to make it work at run-time.  This doesn’t go so well in the editor, though, as the scene manager doesn’t allow you to unload scenes loaded in the editor.

http://pastebin.com/My8q2b1v

 

This will let you reload the scene at runtime using “R”.

 

 

Doing a simple 2d Arc Raycast in Unity

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I was surprised while looking at the unity 2d documentation that there isn’t a simple arc raycast. These are useful for things like jumping, testing the path of projectiles before shooting and other AI goodness.

Here’s the raw code to a simple one. It uses an initial velocity and acceleration, along with some limits to allow you to do a “natural” raycast that returns any colliders along the path.

The result will let you do things like this:

CarverBug_BurrowLines

<pre>

    public static void GetArcHits( out List<RaycastHit2D> Hits, out List<Vector3> Points, int iLayerMask, Vector3 vStart, Vector3 vVelocity, Vector3 vAcceleration, float fTimeStep = 0.05f, float fMaxtime = 10f, bool bDebugDraw = false )
    {
        Hits = new List<RaycastHit2D>();
        Points = new List<Vector3>();
        Vector3 prev = vStart;
        Points.Add( vStart );
        for ( int i = 1; ; i++ )
        {
            float t = fTimeStep*i;
            if ( t > fMaxtime ) break;
            Vector3 pos = PlotTrajectoryAtTime (vStart, vVelocity, vAcceleration, t);
            var result = Physics2D.Linecast (prev,pos, iLayerMask);
            if ( result.collider != null )
            {
                Hits.Add( result );
                Points.Add( pos );
                break;
            }
            else
            {
                Points.Add( pos );
            }
            Debug.DrawLine( prev, pos, Color.Lerp( Color.yellow, Color.red, 0.35f ), 0.5f );
            prev = pos;
        }
    }
    public static Vector3 PlotTrajectoryAtTime (Vector3 start, Vector3 startVelocity, Vector3 acceleration, float fTimeSinceStart)
    {
        return start + startVelocity*fTimeSinceStart + acceleration*fTimeSinceStart*fTimeSinceStart*0.5f;
    }
</pre>