SphereCast with terrain failed

Unity Engine
1

hi guys
i find something very weird
i use Physics.SphereCastAll to find some point in the terrain for my character,the code is like this:
Physics.SphereCastAll( 10000.0f, 0.2f, Vector3.down, 15000.0f, ( int )Game.Define.LayerFlags.Standable );
with very low possiblity,the cast will failed to find a collision,it means i can not place my character

i do some other experiment, and i find that:

when the the distance is closer to the terrain ,the fail possibility will be lower
it seems the result may have something with the float number precision,but as far as i know,the distance in this kind of collision detection algorithm does not matter

if i use Physics.CapsuleCastAll the will be much change to fail
if i use Physics.RayCastAll, it won’t fail (at least in my experiment)

so i think it might be a bug for TerrainCollider anyone have the same problem? or anyone knows what’s going on

2

I’ve used SphereCastAll on terrain and it works fine for me. I suspect you might have an error somewhere. Are you sure your layer flags are correct? If your terrain is on layer 7 for instnace, the flag should be (1 << 7), not 7.

Also, the way you have it written won’t work; the first argument needs to be a vector, the origin position of the sphere. If you’re using javascript maybe it’s converting that 10000f into 0,0,0? The first argument should be the position of your character.

3

thanks for reply
Sorry for not having a clear description
i am sure the collision mask flag is passed corrrectly an the first parameter is also right(in fact i just use the player’s current position + vector.up * 10000.0f)
could do me a favor to generate some random point within the terrain and cast them onto the terrain? thanks

4

here is a simple test script

using UnityEditor;
using UnityEngine;

using System;

namespace ForEditor.Test
{
	static class TerrainRayCastTest
	{
		[MenuItem( "Test/Terrain/Sphere Cast All" )]
		static void SphereCastAll()
		{
			if( Selection.activeGameObject == null || !Selection.activeGameObject.GetComponent<Terrain>() )
				Debug.LogError( DateTime.Now + "\tselect terrain!" );
			else
			{
				var			terrain = Selection.activeGameObject.GetComponent<Terrain>();
				var			data = terrain.terrainData;
				var			size = data.size;

				for( var i = 0; i < 100; ++i )
				{
					var			x = UnityEngine.Random.value * size.x;
					var			z = UnityEngine.Random.value * size.z;
					var			position = new Vector3( x, 10000, z );

					var			hits = Physics.SphereCastAll( position, 0.2f, Vector3.down, 20000 );
					var			index = Array.FindIndex( hits, hit => hit.collider.gameObject.GetInstanceID() == Selection.activeGameObject.GetInstanceID() );

					if( index < 0 )
					{
						Debug.LogError( position + "/" + hits.Length );
						foreach( var hit in hits )
							Debug.Log( "\t" + hit.point );
					}
				}
			}
		}
	}
}

to use it u should first select the terrain object in the hierarchy window and click the menu “Test/Terrain/Sphere Cast All” is sphere failed the will be a error log