From 664c5e02feaf5cf087dc0e30425a107c5b2c34b5 Mon Sep 17 00:00:00 2001
From: Samuele Lorefice <samuelelorefice98@gmail.com>
Date: Wed, 2 Apr 2025 20:26:28 +0200
Subject: [PATCH] Added SDF kernel

---
 SDFMapCreator/Program.cs            | 12 +++++++-----
 SDFMapCreator/SdfKernels.Kernels.cs | 20 ++++++++++++++++++++
 SDFMapCreator/SdfKernels.cs         | 24 ++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/SDFMapCreator/Program.cs b/SDFMapCreator/Program.cs
index d9b6281..0d6d2f1 100644
--- a/SDFMapCreator/Program.cs
+++ b/SDFMapCreator/Program.cs
@@ -133,7 +133,9 @@ public class Program {
         kernels.EdgeDetect(maskData.Mask, out var temp);
         maskData.Mask = temp;
         Parallel.For(0, width * height, parallelOptions, (i) => {
-            if(maskData.Mask[i % width, i / width].Y != 0) lock (maskData.Edges) maskData.Edges.Add(new(i % width, i / width));
+            if (maskData.Mask[i % width, i / width].Y == 0) return;
+            // ReSharper disable once PossibleLossOfFraction
+            lock (maskData.Edges) maskData.Edges.Add(new(i % width, i / width));
         });
         
         sw.Stop();
@@ -179,12 +181,11 @@ public class Program {
     static SDFData SDF(MaskData mask) {
         var width = (uint)mask.Mask.GetLength(0);
         var height = (uint)mask.Mask.GetLength(1);
-        var temp = new Vector3[width, height];
         float AbsMax = MIN;
         int iterCount = 0;
         var sw = new Stopwatch();
         sw.Start();
-        Parallel.For(0, width * height, parallelOptions, (i) =>
+        /*Parallel.For(0, width * height, parallelOptions, (i) =>
         {
             //convert 1D index to 2D index
             var x = (int)(i % width);
@@ -210,8 +211,9 @@ public class Program {
                 ConsoleUpdateLine(
                     $"Progress: {iterCount / (float)(width * height):P}% | {iterCount / (sw.Elapsed.TotalSeconds):N0} pixels/s");
             }
-        });
-
+        });*/
+        kernels.Sdf(mask.Edges.ToArray(), out var temp);
+        
         Console.WriteLine(
             $"\nSDF Generation Time: {sw.Elapsed.TotalSeconds:N4}s ({iterCount / sw.Elapsed.TotalSeconds:N0} pixels/s)");
         sw.Restart();
diff --git a/SDFMapCreator/SdfKernels.Kernels.cs b/SDFMapCreator/SdfKernels.Kernels.cs
index 0da0cd2..05ccfba 100644
--- a/SDFMapCreator/SdfKernels.Kernels.cs
+++ b/SDFMapCreator/SdfKernels.Kernels.cs
@@ -49,4 +49,24 @@ public partial class SdfKernels {
            }
        }
     }
+
+    private static void SdfKernel(Index2D index,
+        ArrayView2D<Vector3, Stride2D.DenseX> sdf,
+        ArrayView1D<Vector2, Stride1D.Dense> edges,
+        int width, int height
+    ) {
+        Vector2 pos = new((float)index.X / width, (float)index.Y / height);
+        float minDist = 2f;
+        int count = edges.IntExtent.X;
+        
+        for (int i = 0; i < count; i++) {
+            Vector2 edgeNrm = new (edges[i].X/width, edges[i].Y/height);
+            float dist = Vector2.Distance(pos, edgeNrm);
+            if (dist < minDist) minDist = dist;
+        }
+
+        if (minDist > 1f) minDist = 1f;
+       
+        sdf[index] = new(minDist);
+    }
 }
\ No newline at end of file
diff --git a/SDFMapCreator/SdfKernels.cs b/SDFMapCreator/SdfKernels.cs
index a2f2246..4a9c995 100644
--- a/SDFMapCreator/SdfKernels.cs
+++ b/SDFMapCreator/SdfKernels.cs
@@ -106,6 +106,30 @@ public partial class SdfKernels {
         edge = buffer.GetAsArray2D();
     }
     
+    public void Sdf(Vector2[] edges, out Vector3[,] sdf) {
+        var dev = gpuContext.GetPreferredDevice(preferCPU:false);
+        int width = edges.Length;
+        int height = edges.Length;
+        sdf = new Vector3[width, height];
+        using Accelerator accelerator = dev.CreateAccelerator(gpuContext);
+        
+        using var buffer = accelerator.Allocate2DDenseX<Vector3>(new (width, height));
+        
+        using var edgeBuffer = accelerator.Allocate1D<Vector2>(edges.Length);
+        edgeBuffer.CopyFromCPU(edges);
+        
+        var sdfKernel = accelerator.LoadAutoGroupedStreamKernel<Index2D,
+            ArrayView2D<Vector3, Stride2D.DenseX>,
+            ArrayView1D<Vector2, Stride1D.Dense>,
+            int, int>(SdfKernel);
+
+        sdfKernel(new (width, height), buffer.View, edgeBuffer.View, width, height);
+        
+        accelerator.Synchronize();
+
+        sdf = buffer.GetAsArray2D();
+    }
+    
     private static string GetInfoString(Accelerator a)
     {
         StringWriter infoString = new StringWriter();