hole flip trick, with box mat chain

Assets/backbox.hlsl

@@ -45,6 +45,6 @@ float4 ps(psIn input) : SV_TARGET {
 	// Fresnel effect calculation
 	float fresnel = 1.0 - saturate(dot(-view_dir, input.normal));
 	fresnel = pow(fresnel, 5.0); // Adjust power for different falloff rates
-	
+	float value = 0.5;
-	return float4(fresnel * input.color.rgb, input.color.a);
+	return float4(fresnel * input.color.rgb * value, input.color.a);
 }

Platforms/Android/AndroidManifest.xml

@@ -2,8 +2,8 @@
 <manifest
   xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.dofdev.snake"
-  android:versionCode="13"
+  android:versionCode="14"
-  android:versionName="1.21"
+  android:versionName="1.24"
   android:installLocation="auto"
 >
   <uses-sdk android:minSdkVersion="29" android:targetSdkVersion="32" />

src/Arts.cs

@@ -9,7 +9,7 @@ static class Arts
     static Dictionary<string, Mesh> meshes = new();
     static Material mat_mono = new Material("mono.hlsl");
     static Material mat_unlit = new Material("unlit.hlsl");
-    // [!] have backfaces on a mat run a separate backbox/face shader]? *to try and reduce drawcalls
+    static Material mat_box = new Material("unlit.hlsl");
     static Material mat_backbox = new Material("backbox.hlsl");
     static Material mat_justcolor = new Material("justcolor.hlsl");
 
@@ -30,10 +30,13 @@ static class Arts
             }
         }
 
+
         mat_backbox.FaceCull = Cull.Front;
         mat_backbox.Transparency = Transparency.Add;
         mat_backbox.DepthTest = DepthTest.LessOrEq;
         mat_backbox.DepthWrite = false;
+
+        mat_box.Chain = mat_backbox;
     }
 
     public static void Frame()
@@ -62,11 +65,10 @@ static class Arts
 
         // box
         Hierarchy.Push(Mono.box_pose.ToMatrix(Mono.box_scale));
-        meshes["InsideOut"].Draw(mat_unlit, Matrix.Identity);
+        // meshes["InsideOut"].Draw(mat_unlit, Matrix.Identity);
         meshes["InsideOut"].Draw(
-            mat_backbox,
+            mat_box,
-            Matrix.Identity,
+            Matrix.Identity
-            new Color(0.2f, 0.2f, 0.2f)
         );
         meshes["Corrugation"].Draw(
             Mono.in_dist.state ? mat_justcolor : mat_unlit,
@@ -161,18 +163,19 @@ static class Arts
                 Maths.abs(hole.Value.y) * Maths.sign(hole.Key.y),
                 Maths.abs(hole.Value.z) * Maths.sign(hole.Key.z)
             );
-            Vec3 hole_world_normal = Mono.box_pose.orientation * hole_normal;
+            // Vec3 hole_world_normal = Mono.box_pose.orientation * hole_normal;
-            Vec3 hole_world = Mono.box_pose.ToMatrix(Mono.box_scale) * V.XYZ(
+            // Vec3 hole_world = Mono.box_pose.ToMatrix(Mono.box_scale) * V.XYZ(
-                hole.Key.x - hole.Value.x * 0.5f,
+            //     hole.Key.x - hole.Value.x * 0.5f,
-                hole.Key.y - hole.Value.y * 0.5f,
+            //     hole.Key.y - hole.Value.y * 0.5f,
-                hole.Key.z - hole.Value.z * 0.5f
+            //     hole.Key.z - hole.Value.z * 0.5f
-            );
+            // );
             // Vec3 cam_dir = (Rig.head.orientation * Vec3.Forward);
-            Vec3 hole_view_dir = Vec3.Direction(hole_world, Rig.head.position);
+            // Vec3 hole_view_dir = Vec3.Direction(hole_world, Rig.head.position);
-            bool back_hole = Vec3.Dot(hole_world_normal, hole_view_dir) < 0.0;
+            // bool back_hole = Vec3.Dot(hole_world_normal, hole_view_dir) < 0.0;
+            bool hole_flip = Vec3.Dot(hole_normal, hole.Value.ToVec3) < 0.0;
 
-            meshes["Hole"].Draw(
+            meshes[hole_flip ? "Hole" : "HoleFlip"].Draw(
-                back_hole ? mat_backbox : mat_unlit,
+                mat_box,
                 Matrix.TRS(
                     hole.Key.ToVec3,
                     Quat.LookDir(hole.Value.ToVec3),