refactor: Use CollectionsMarshal.SetCount to resize lists (#2945)

Makes code easier to read (as it was before a122c71).
The SetCount implementation looks very similar to the previously used Resize method of FastList.
For value types it just sets the internal count, for reference types it clears the pointers. Both what was done before as well.

Author: azeno

sources/engine/Stride.Engine/Rendering/Compositing/ForwardRenderer.cs

@@ -471,16 +471,7 @@ protected static PixelFormat ComputeNonMSAADepthFormat(PixelFormat format)
         private void ResolveMSAA(RenderDrawContext drawContext)
         {
             // Resolve render targets
-            if (currentRenderTargetsNonMSAA.Count < currentRenderTargets.Count)
-            {
-                currentRenderTargetsNonMSAA.EnsureCapacity(currentRenderTargets.Count);
-                while (currentRenderTargetsNonMSAA.Count != currentRenderTargets.Count)
-                    currentRenderTargetsNonMSAA.Add(null);
-            }
-            else if (currentRenderTargetsNonMSAA.Count > currentRenderTargets.Count)
-            {
-                currentRenderTargetsNonMSAA.RemoveRange(currentRenderTargets.Count, currentRenderTargetsNonMSAA.Count - currentRenderTargets.Count);
-            }
+            CollectionsMarshal.SetCount(currentRenderTargetsNonMSAA, currentRenderTargets.Count);
 
             for (int index = 0; index < currentRenderTargets.Count; index++)
             {
@@ -849,16 +840,7 @@ private void PrepareRenderTargets(RenderDrawContext drawContext, Texture outputR
 
             var renderTargets = OpaqueRenderStage.OutputValidator.RenderTargets;
 
-            if (currentRenderTargets.Count < renderTargets.Count)
-            {
-                currentRenderTargets.EnsureCapacity(renderTargets.Count);
-                while (currentRenderTargets.Count != renderTargets.Count)
-                    currentRenderTargets.Add(null);
-            }
-            else if (currentRenderTargets.Count > renderTargets.Count)
-            {
-                currentRenderTargets.RemoveRange(renderTargets.Count, currentRenderTargets.Count - renderTargets.Count);
-            }
+            CollectionsMarshal.SetCount(currentRenderTargets, renderTargets.Count);
 
             for (int index = 0; index < renderTargets.Count; index++)
             {

sources/engine/Stride.Rendering/Rendering/RenderSystem.cs

@@ -10,6 +10,7 @@
 using Stride.Core.Threading;
 using Stride.Core.Diagnostics;
 using Stride.Graphics;
+using System.Runtime.InteropServices;
 
 namespace Stride.Rendering
 {
@@ -285,16 +286,7 @@ public unsafe void Prepare(RenderDrawContext context)
                         var renderStage = RenderStages[renderViewStage.Index];
                         var sortedRenderNodes = renderViewStage.SortedRenderNodes;
 
-                        if (sortedRenderNodes.Count < renderNodes.Count)
-                        {
-                            sortedRenderNodes.EnsureCapacity(renderNodes.Count);
-                            while (sortedRenderNodes.Count != renderNodes.Count)
-                                sortedRenderNodes.Add(default);
-                        }
-                        else if (sortedRenderNodes.Count > renderNodes.Count)
-                        {
-                            sortedRenderNodes.RemoveRange(renderNodes.Count, sortedRenderNodes.Count - renderNodes.Count);
-                        }
+                        CollectionsMarshal.SetCount(sortedRenderNodes, renderNodes.Count);
 
                         if (renderStage.SortMode != null)
                         {