# RaycastNonAlloc

> Cast a ray through the Scene and store the hits into the buffer.

## Definition

* **Type:** Method
* **Namespace:** [UnityEngine](/engine/6000.7/script-reference/unityengine.md)
* **Assembly:** UnityEngine.PhysicsModule

## RaycastNonAlloc(Ray, RaycastHit\[], float, int, QueryTriggerInteraction)

Cast a ray through the Scene and store the hits into the buffer.

```csharp
public static int RaycastNonAlloc(Ray ray, RaycastHit[] results, float maxDistance, int layerMask, QueryTriggerInteraction queryTriggerInteraction)
```

### Parameters

**** (\[Ray]\(/engine/6000.7/script-reference/unityengine/ray)): The starting point and direction of the ray.**** (\[RaycastHit\[]]\(/engine/6000.7/script-reference/unityengine/raycasthit)): The buffer to store the hits into.**** (\[float]\(https\://learn.microsoft.com/dotnet/api/system.single)): The max distance the rayhit is allowed to be from the start of the ray.**** (\[int]\(https\://learn.microsoft.com/dotnet/api/system.int32)): A Layer mask that is used to selectively filter which colliders are considered when casting a ray.**** (\[QueryTriggerInteraction]\(/engine/6000.7/script-reference/unityengine/querytriggerinteraction)): Specifies whether this query should hit Triggers.

### Returns

| Type                                                       | Description                                          |
| ---------------------------------------------------------- | ---------------------------------------------------- |
| [int](https://learn.microsoft.com/dotnet/api/system.int32) | The amount of hits stored into the `results` buffer. |

### Remarks

Like [Physics.RaycastAll](/engine/6000.7/script-reference/unityengine/physics/raycastall.md), but generates no garbage.

The raycast query ends when there are no more hits and/or the results buffer is full. The order of the results is undefined. When a full buffer is returned it is not guaranteed that the results are the closest hits and the length of the buffer is returned. If a null buffer is passed in, no results are returned and no errors or exceptions are thrown.

## RaycastNonAlloc(Vector3, Vector3, RaycastHit\[], float, int, QueryTriggerInteraction)

Cast a ray through the Scene and store the hits into the buffer.

```csharp
public static int RaycastNonAlloc(Vector3 origin, Vector3 direction, RaycastHit[] results, float maxDistance, int layerMask, QueryTriggerInteraction queryTriggerInteraction)
```

### Parameters

**** (\[Vector3]\(/engine/6000.7/script-reference/unityengine/vector3)): The starting point and direction of the ray.**** (\[Vector3]\(/engine/6000.7/script-reference/unityengine/vector3)): The direction of the ray.**** (\[RaycastHit\[]]\(/engine/6000.7/script-reference/unityengine/raycasthit)): The buffer to store the hits into.**** (\[float]\(https\://learn.microsoft.com/dotnet/api/system.single)): The max distance the rayhit is allowed to be from the start of the ray.**** (\[int]\(https\://learn.microsoft.com/dotnet/api/system.int32)): A Layer mask that is used to selectively filter which colliders are considered when casting a ray.**** (\[QueryTriggerInteraction]\(/engine/6000.7/script-reference/unityengine/querytriggerinteraction)): Specifies whether this query should hit Triggers.

### Returns

| Type                                                       | Description                                          |
| ---------------------------------------------------------- | ---------------------------------------------------- |
| [int](https://learn.microsoft.com/dotnet/api/system.int32) | The amount of hits stored into the `results` buffer. |

### Examples

```csharp
using UnityEngine;

public class RaycastFanNonAlloc : MonoBehaviour
{
    public int rayCount = 10;                       // Number of rays in the fan
    public float angle = 60f;                       // Total spread angle in degrees
    public float maxDistance = 20f;                 // Ray length

    // The size of the array determines how many raycasts will occur
    RaycastHit[] m_Results = new RaycastHit[5];     // Reused buffer to avoid GC allocations

    // See https://docs.unity.com/engine/6000.7/manual/scripting/managing-update-order/execution-order for information on FixedUpdate() and Update() related to physics queries
    void FixedUpdate()
    {
        Vector3 origin = transform.position;
        Vector3 forward = transform.forward;
        float halfAngle = angle / 2f;

        for (int i = 0; i < rayCount; i++)
        {
            // Interpolate angle across the spread range
            float lerp = (float)i / (rayCount - 1);
            float currentAngle = Mathf.Lerp(-halfAngle, halfAngle, lerp);

            // Rotate direction around Y axis
            Quaternion rotation = Quaternion.AngleAxis(currentAngle, Vector3.up);
            Vector3 direction = rotation * forward;

            // Note: The buffer is overwritten from index 0 up to the number of hits returned. Unused slots remain unchanged.
            int hits = Physics.RaycastNonAlloc(origin, direction, m_Results, maxDistance);

            if (hits > 0)
            {
                for (int j = 0; j < hits; j++)
                {
                    Debug.Log($"Ray {i} hit {m_Results[j].collider.gameObject.name}");
                    Debug.DrawLine(origin, m_Results[j].point, Color.green);
                }
            }
            else
            {
                Debug.DrawRay(origin, direction * maxDistance, Color.red);
            }
        }
    }
}
```