Prevent selection of objects when backface culling enabled

Prevent selecting an object if its normal is pointed away from the camera and backface culling is enabled
igorseabra4 · Sep 17, 2024 · 9b73152 · 9b73152
1 parent 2d1e9b3
commit 9b73152
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Showing 3 changed files with 25 additions and 4 deletions.
diff --git a/IndustrialPark/Assets/ObjectAssets/ClickableAssets/PlaceableAssets/AssetUI.cs b/IndustrialPark/Assets/ObjectAssets/ClickableAssets/PlaceableAssets/AssetUI.cs
@@ -196,7 +196,7 @@ public override bool ShouldDraw(SharpRenderer renderer)
         [Browsable(false)]
         public override bool SpecialBlendMode => true;
 
-        protected override float? TriangleIntersection(Ray r)
+        protected override float? TriangleIntersection(Ray r, bool hitBackFaces = true)
         {
             if (Texture == 0)
                 return base.TriangleIntersection(r);

diff --git a/IndustrialPark/Assets/Shared/EntityAsset.cs b/IndustrialPark/Assets/Shared/EntityAsset.cs
@@ -6,6 +6,7 @@
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Windows.Forms;
+using SharpDX.Direct3D11;
 using static IndustrialPark.ArchiveEditorFunctions;
 
 namespace IndustrialPark
@@ -325,19 +326,34 @@ public virtual void Draw(SharpRenderer renderer)
 
         public virtual float? GetIntersectionPosition(SharpRenderer renderer, Ray ray)
         {
+            var backfaceCulling = renderer.device.NormalCullMode == CullMode.Back;
+            // If backface culling is enabled, rays should pass through the back of the faces
+
             if (ShouldDraw(renderer) && ray.Intersects(ref boundingBox))
-                return triangles == null ? TriangleIntersection(ray, SharpRenderer.cubeTriangles, SharpRenderer.cubeVertices, world) : TriangleIntersection(ray);
+                return triangles == null ? TriangleIntersection(ray, SharpRenderer.cubeTriangles, SharpRenderer.cubeVertices, world) : TriangleIntersection(ray, !backfaceCulling);
             return null;
         }
 
-        protected virtual float? TriangleIntersection(Ray ray)
+        protected virtual float? TriangleIntersection(Ray ray, bool hitBackfaces = true)
         {
             float? smallestDistance = null;
 
             foreach (RenderWareFile.Triangle t in triangles)
-                if (ray.Intersects(ref vertices[t.vertex1], ref vertices[t.vertex2], ref vertices[t.vertex3], out float distance))
+                if (ray.Intersects(ref vertices[t.vertex1], ref vertices[t.vertex2], ref vertices[t.vertex3],
+                        out float distance))
+                {
+                    // If backface culling is enabled, rays should pass through the back of the faces
+                    if (!hitBackfaces)
+                    {
+                        var normal = Vector3.Cross(vertices[t.vertex2] - vertices[t.vertex1], vertices[t.vertex3] - vertices[t.vertex1]);
+                        if (Vector3.Dot(normal, ray.Direction) > 0)
+                            continue;
+                    }
+
                     if (smallestDistance == null || distance < smallestDistance)
                         smallestDistance = distance;
+                }
+
 
             return smallestDistance;
         }

diff --git a/IndustrialPark/SharpDX/SharpDevice.cs b/IndustrialPark/SharpDX/SharpDevice.cs
@@ -241,6 +241,11 @@ public void ApplyRasterState()
 
         private CullMode normalCullMode = CullMode.Back;
         private FillMode normalFillMode = FillMode.Solid;
+
+        public CullMode NormalCullMode
+        {
+            get => normalCullMode;
+        }
 
         public void SetNormalCullMode(CullMode cullMode)
         {