Question by aleksanderpiciga · Jan 23 at 10:46 PM · collision raycast collider mesh blender

Why are my Physics.RayCast not showing the collsion with the Ground?

Hello! I have an issue where my RayCast always returns (0,0,0) as point of collision. I am trying to set random positions of enemies (x and z) and place them under the map at a set y value and then cast a ray upwards to detect where it collides with the Ground (I am using Blenders generated plane which isn't convex but i have made sure to enable Mesh Colliders and have checked that they do display correctly). When i cast a ray i always get a result of (0,0,0) as collision point with the ground or in other words no collision. Sometimes howerve i got collision points but only for 1 out of 50 enemies. I have also drawn the same rays i am casting using Debug.DrawRay and they do intersect with the Blender's Plane. They only thing i can think of is that Ground colliders is simply too thin? I have also checked multiple layerMakss values (such as all and none) and have set Ground's layerMask to Ground.

CODE (for loop where i generate enemies and try to get collision point between new enemy and the ground I'm not sure if this is the best way to spawn enemies but i think it should work so i would be very thankful if anyone has any idea what have i done wrong. THANKS A LOT!

 for (int i = 0; i < numOfBasicEnemies; i++)
         {
             GameObject newEnemy = Instantiate(basicEnemy, enemiesParentObject);
 
             // Set new position of an enemy
             Vector3 tempPos = new Vector3(0,-2 * mapHeight, 0); // Set position under the map 2* mapHeight under the map (under y = 0)
             tempPos.x = Random.Range(-xSpawnLimit, xSpawnLimit);
             tempPos.z = Random.Range(-zSpawnLimit, zSpawnLimit);
 
             Vector3 rayOrigin = tempPos + new Vector3(0, 20, 0); // Start the ray a bit above the enemy
             Vector3 rayDirection = Vector3.up; // Point the ray upwards
 
             RaycastHit rayCastHitInfo; // Ray call back object
             Physics.Raycast(rayOrigin, rayDirection, out rayCastHitInfo, 4 * mapHeight, layerMask);
                                                                         // ^^ -> cast ray 2 * mapHeight above the map (above y = 0)
             Debug.DrawRay(rayOrigin, rayDirection * (4 * mapHeight), new Color(255, 0, 0), 100f, true);
 
             Vector3 groundPoint = rayCastHitInfo.point;
             Debug.Log(groundPoint);
            
             newEnemy.transform.position = tempPos;
 
             newEnemy.GetComponent<basicEnemy>().color = gameVaraibles.colorOptions[Random.Range(0, gameVaraibles.colorOptions.Length)];
             //newEnemy.GetComponent<Rigidbody>().useGravity = true;
             newEnemy.GetComponent<basicEnemy>().loadEnemy();
 
             newEnemy.GetComponent<CapsuleCollider>().enabled = true;
         }
         basicEnemy.SetActive(false);

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NVJOB · Jan 23 at 11:37 PM 3

This is a fully working script (this is an example).

You need to look at lines 22 - 23, there lies the method you need.

Explanatory video - https://www.youtube.com/watch?v=b9HhgzMuYxM

 using UnityEngine;
 
 public class Spawn : MonoBehaviour
 {
     public GameObject enemy;
     public float radiusSpawn = 10;
     public int numOfBasicEnemies = 10;
     public LayerMask groundLayer;
     Transform tr;
     RaycastHit hit;
 
     void Awake()
     {
         tr = transform;    
     }    
 
     void Start()
     {
         for (int i = 0; i < numOfBasicEnemies; i++)
         {
             Vector2 randomCircle = Random.insideUnitCircle * radiusSpawn;
             Vector3 v3rc = new Vector3(tr.position.x + randomCircle.x, 100, tr.position.z + randomCircle.y);
             if (Physics.Raycast(v3rc, Vector3.down, out hit, 150, groundLayer))
             {
                 GameObject enemyRay = Instantiate(enemy);
                 enemyRay.transform.SetPositionAndRotation(new Vector3(v3rc.x, hit.point.y + 2.0f, v3rc.z), tr.rotation);
                 enemyRay.transform.parent = tr;
             }
         }
     }
 }