# Create the ray tracing context

The [`RayTracingContext`](xref:UnityEngine.Rendering.UnifiedRayTracing.RayTracingContext) serves as the initial API entry point, allowing the creation of all essential objects required to execute ray tracing code.

Follow these steps:
1. Load the ray tracing resources.
2. Create the context.

## Load the ray tracing resources
The [`RayTracingContext`](xref:UnityEngine.Rendering.UnifiedRayTracing.RayTracingContext) needs a few utility shaders that the [`RayTracingResources`](xref:UnityEngine.Rendering.UnifiedRayTracing.RayTracingResources) object supplies. You can load these resources in several different ways.

If your project uses SRP (Scriptable Render Pipeline), load the resources via [`RayTracingResources.LoadFromRenderPipelineResources`](xref:UnityEngine.Rendering.UnifiedRayTracing.RayTracingResources.LoadFromRenderPipelineResources()). This always works in the Editor.
```C#
var rtResources = new RayTracingResources();
bool result = rtResources.LoadFromRenderPipelineResources();
```
You can instruct Unity to also include the resources in Player builds:
```C#
using UnityEngine.Rendering;
using UnityEngine.Rendering.UnifiedRayTracing;

#if UNITY_EDITOR
class MyURTStripping: IRenderPipelineGraphicsSettingsStripper<RayTracingRenderPipelineResources>
{
    public bool active => true;
    public bool CanRemoveSettings(RayTracingRenderPipelineResources settings) => false;
}
#endif
```

You can also load the resources via the Asset Database:
```C# 
var rtResources = new RayTracingResources();
rtResources.Load();
```
**Note:** Since the Player doesn't give access to the Asset Database, this method only works in the Editor.

To load the [`RayTracingResources`](xref:UnityEngine.Rendering.UnifiedRayTracing.RayTracingResources) in the Player, you can also build an AssetBundle that includes the following SRP Core files:
- `Runtime/UnifiedRayTracing/Common/GeometryPool/GeometryPoolKernels.compute`
- `Runtime/UnifiedRayTracing/Common/Utilities/CopyBuffer.compute`
- `Runtime/UnifiedRayTracing/Compute/RadeonRays/kernels/copyPositions.compute`
- `Runtime/UnifiedRayTracing/Compute/RadeonRays/kernels/bit_histogram.compute`
- `Runtime/UnifiedRayTracing/Compute/RadeonRays/kernels/block_reduce_part.compute`
- `Runtime/UnifiedRayTracing/Compute/RadeonRays/kernels/block_scan.compute`
- `Runtime/UnifiedRayTracing/Compute/RadeonRays/kernels/build_hlbvh.compute`
- `Runtime/UnifiedRayTracing/Compute/RadeonRays/kernels/restructure_bvh.compute`
- `Runtime/UnifiedRayTracing/Compute/RadeonRays/kernels/scatter.compute`

For more information about building and loading AssetBundles, refer to [AssetBundles](xref:AssetBundlesIntro).

After you build the AssetBundle, use the following code to load it:
```C# 
var rtResources = new RayTracingResources();

// Load the AssetBundle 
var asssetBundle = AssetBundle.LoadFromFile("Assets/pathToYourBuiltAssetBundles/unifiedraytracing");

// Load the RayTracingResources
rtResources.LoadFromAssetBundle(asssetBundle);
```

## Create the context
Once the [`RayTracingResources`](xref:UnityEngine.Rendering.UnifiedRayTracing.RayTracingResources) are loaded, use them to create the [`RayTracingContext`](xref:UnityEngine.Rendering.UnifiedRayTracing.RayTracingContext).
```C# 
var context = new RayTracingContext(rtResources);
```

By default, Unity checks if the device supports hardware ray tracing, and selects either hardware ray tracing or compute shaders. To manually select the backend, pass in a `RayTracingBackend`. For example:

```C# 
var backend = RayTracingBackend.Compute;
var context = new RayTracingContext(backend, rtResources);
```