diff --git a/Assets/Resources/FSR2/ffx_fsr2_compute_luminance_pyramid_pass.compute b/Assets/Resources/FSR2/ffx_fsr2_compute_luminance_pyramid_pass.compute
index 2cdf974..5c1d47c 100644
--- a/Assets/Resources/FSR2/ffx_fsr2_compute_luminance_pyramid_pass.compute
+++ b/Assets/Resources/FSR2/ffx_fsr2_compute_luminance_pyramid_pass.compute
@@ -2,6 +2,6 @@
 
 #define FFX_GPU         // Compiling for GPU
 #define FFX_HLSL        // Compile for plain HLSL
-#define SPD_NO_WAVE_OPERATIONS  // Wave operations require shader model 6.0
+#define SPD_NO_WAVE_OPERATIONS  // Wave operations require shader model 6.0; this works with #pragma use_dxc but only on D3D12
 
 #include "shaders/ffx_fsr2_compute_luminance_pyramid_pass.hlsl"
diff --git a/Assets/Scripts/FSR2Thing.cs b/Assets/Scripts/FSR2Thing.cs
index a3ee6e6..98f2ec9 100644
--- a/Assets/Scripts/FSR2Thing.cs
+++ b/Assets/Scripts/FSR2Thing.cs
@@ -3,6 +3,7 @@ using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using System.Runtime.InteropServices;
+using FidelityFX;
 using UnityEditor;
 using UnityEngine;
 using UnityEngine.Rendering;
@@ -24,6 +25,8 @@ public class FSR2Thing : MonoBehaviour
     [HideInInspector]
     public float renderScale;
 
+    public Fsr2Callbacks callbacks;
+
     private RenderTexture _upscaleRT;
     private RenderTexture _rcasOutput;
     private Texture2D _exposure;
@@ -35,7 +38,7 @@ public class FSR2Thing : MonoBehaviour
         {
             if (_testMaterial == null)
             {
-                var testShader = Shader.Find("FSR2/FSRTest");
+                var testShader = callbacks.LoadShader("FSR2/FSRTest");
                 _testMaterial = new Material(testShader);
             }
 
@@ -50,9 +53,7 @@ public class FSR2Thing : MonoBehaviour
         {
             if (_rcasComputeShader == null)
             {
-                // TODO: this is nasty, I don't like this. How do we manage/bind compute shaders best? => make a Callbacks class/interface with overridable implementation
-                // GPUInstancer used Resources, we modified that to load stuff from asset bundles instead. Maybe provide a custom loader callback interface?
-                _rcasComputeShader = Resources.Load<ComputeShader>("FSR2/ffx_fsr2_rcas_pass");
+                _rcasComputeShader = callbacks.LoadComputeShader("FSR2/ffx_fsr2_rcas_pass");
             }
 
             return _rcasComputeShader;
@@ -61,6 +62,9 @@ public class FSR2Thing : MonoBehaviour
 
     private ComputeBuffer _fsr2ConstantsBuffer;
     private readonly Fsr2Constants[] _fsr2ConstantsArray = { new Fsr2Constants() };
+
+    private ComputeBuffer _spdConstantsBuffer;
+    private readonly SpdConstants[] _spdConstantsArray = { new SpdConstants() };
     
     private ComputeBuffer _rcasConstantsBuffer;
     private readonly RcasConstants[] _rcasConstantsArray = new RcasConstants[1];
@@ -82,6 +86,7 @@ public class FSR2Thing : MonoBehaviour
         _exposure.Apply();
 
         _fsr2ConstantsBuffer = new ComputeBuffer(1, Marshal.SizeOf<Fsr2Constants>(), ComputeBufferType.Constant);
+        _spdConstantsBuffer = new ComputeBuffer(1, Marshal.SizeOf<SpdConstants>(), ComputeBufferType.Constant);
         _rcasConstantsBuffer = new ComputeBuffer(1, Marshal.SizeOf<RcasConstants>(), ComputeBufferType.Constant);
     }
 
@@ -93,6 +98,12 @@ public class FSR2Thing : MonoBehaviour
             _rcasConstantsBuffer = null;
         }
 
+        if (_spdConstantsBuffer != null)
+        {
+            _spdConstantsBuffer.Release();
+            _spdConstantsBuffer = null;
+        }
+
         if (_fsr2ConstantsBuffer != null)
         {
             _fsr2ConstantsBuffer.Release();
@@ -207,6 +218,15 @@ public class FSR2Thing : MonoBehaviour
         public float lumaMipRcp;
     }
 
+    [Serializable, StructLayout(LayoutKind.Sequential)]
+    private struct SpdConstants
+    {
+        public uint mips;
+        public uint numWorkGroups;
+        public uint workGroupOffsetX, workGroupOffsetY;
+        public uint renderSizeX, renderSizeY;
+    }
+
     private static readonly List<RcasConstants> RcasConfigs = new()
     {
         new(1048576000u, 872428544u),
diff --git a/Assets/Scripts/Fsr2Callbacks.cs b/Assets/Scripts/Fsr2Callbacks.cs
new file mode 100644
index 0000000..b4a6272
--- /dev/null
+++ b/Assets/Scripts/Fsr2Callbacks.cs
@@ -0,0 +1,29 @@
+using UnityEngine;
+
+namespace FidelityFX
+{
+    public class Fsr2Callbacks
+    {
+        public virtual Shader LoadShader(string name)
+        {
+#if UNITY_EDITOR
+            return Shader.Find(name);
+#else
+            return Resources.Load<Shader>(name);
+#endif
+        }
+
+        public virtual ComputeShader LoadComputeShader(string name)
+        {
+            return Resources.Load<ComputeShader>(name);
+        }
+
+        public virtual void ApplyMipmapBias(float biasOffset)
+        {
+            foreach (var texture in Resources.FindObjectsOfTypeAll<Texture2D>())
+            {
+                texture.mipMapBias += biasOffset;
+            }
+        }
+    }
+}
diff --git a/Assets/Scripts/Fsr2Callbacks.cs.meta b/Assets/Scripts/Fsr2Callbacks.cs.meta
new file mode 100644
index 0000000..abc4d96
--- /dev/null
+++ b/Assets/Scripts/Fsr2Callbacks.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 5906deeb6ec2854449bf33db2e71a046
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Assets/Scripts/SubsampleTest.cs b/Assets/Scripts/SubsampleTest.cs
index 6043e2c..47d9ddb 100644
--- a/Assets/Scripts/SubsampleTest.cs
+++ b/Assets/Scripts/SubsampleTest.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using FidelityFX;
 using UnityEngine;
 
 [RequireComponent(typeof(Camera))]
@@ -17,6 +18,8 @@ public class SubsampleTest : MonoBehaviour
     [SerializeField]
     private bool enableJitter;
 
+    private Fsr2Callbacks callbacks = new Fsr2Callbacks();
+    
     private FSR2Thing fsr2Thing;
     
     private void OnEnable()
@@ -33,6 +36,7 @@ public class SubsampleTest : MonoBehaviour
             outputCamera.eventMask = 0;
             
             fsr2Thing = outputCameraObject.AddComponent<FSR2Thing>();
+            fsr2Thing.callbacks = callbacks;
             fsr2Thing.gameCamera = gameCamera;
             fsr2Thing.outputCamera = outputCamera;
             fsr2Thing.renderScale = renderScale;
@@ -60,21 +64,14 @@ public class SubsampleTest : MonoBehaviour
         
         // Adjust texture mipmap LOD bias by log2(renderResolution/displayResolution) - 1.0;
         // May need to leave this to the game dev, as we don't know which textures do and don't belong to the 3D scene
-        // TODO: add to Callbacks class/interface (ApplyMipmapBias)
         float biasOffset = GetMipmapBiasOffset();
-        foreach (var tex in Resources.FindObjectsOfTypeAll<Texture2D>())
-        {
-            tex.mipMapBias += biasOffset;
-        }
+        callbacks.ApplyMipmapBias(biasOffset);
     }
 
     private void OnDisable()
     {
         float biasOffset = GetMipmapBiasOffset();
-        foreach (var tex in Resources.FindObjectsOfTypeAll<Texture2D>())
-        {
-            tex.mipMapBias -= biasOffset;
-        }
+        callbacks.ApplyMipmapBias(-biasOffset);
         
         gameCamera.targetTexture.Release();
         gameCamera.targetTexture = null;