Added textures and materials and scene from half-life 2

Assets/occlusion-portals/shaders/InteriorImposterShader.shader

@@ -0,0 +1,83 @@
+// Original code from https://gist.github.com/josephbk117/a43f5335cea9b3e12a44f196dc81f30f
+Shader "Custom/InteriorImposterShader"
+{
+    Properties
+    {
+    }
+
+    SubShader
+    {
+        Pass
+        {
+            CGPROGRAM
+            #pragma vertex vert
+            #pragma fragment frag
+            #include "UnityCG.cginc"
+            #include "Lighting.cginc"
+
+            struct appdata
+            {
+                float4 vertex : POSITION;
+                float3 normal : NORMAL;
+            };
+
+            struct v2f 
+            {
+                float3 worldPos : TEXCOORD0;
+                float3 worldNormal : TEXCOORD1;
+                float4 pos : SV_POSITION;
+            };
+
+            v2f vert (appdata v)
+            {
+                v2f o;
+                o.pos = UnityObjectToClipPos(v.vertex);
+                o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
+                o.worldNormal = UnityObjectToWorldNormal(v.normal);
+                return o;
+            }
+
+            // Snippet from https://github.com/frostbone25/Unity-Improved-Box-Projected-Reflections/blob/main/ImprovedBoxProjectedReflections/Assets/Shaders/ImprovedBoxProjectedReflections.shader#L80
+            float3 BoxProjectReflectionDir(float3 worldPos, float3 worldRefl, out float distanceToHitPoint)
+            {
+                float4 probePos = unity_SpecCube0_ProbePosition;
+                float4 boxMin = unity_SpecCube0_BoxMin;
+                float4 boxMax = unity_SpecCube0_BoxMax;
+
+                // Do we have a valid reflection probe?
+                if (probePos.w > 0.0)
+                {
+                    float3 nrdir = normalize(worldRefl);
+
+                    float3 rbmax = (boxMax.xyz - worldPos) / nrdir;
+                    float3 rbmin = (boxMin.xyz - worldPos) / nrdir;
+
+                    float3 rbminmax = (nrdir > 0.0f) ? rbmax : rbmin;
+
+                    distanceToHitPoint = min(min(rbminmax.x, rbminmax.y), rbminmax.z);
+
+                    worldPos -= probePos.xyz;
+                    worldRefl = worldPos + nrdir * distanceToHitPoint;
+                }
+
+                return worldRefl;
+            }
+
+            fixed4 frag (v2f i) : SV_Target
+            {
+                float mipLevel = 0.0;
+
+                half3 worldViewDir = normalize(UnityWorldSpaceViewDir(i.worldPos));  // Direction of ray from the camera towards the object surface
+                float3 boxProjection = BoxProjectReflectionDir(i.worldPos, -worldViewDir, mipLevel);
+
+                mipLevel = (mipLevel / UNITY_SPECCUBE_LOD_STEPS) * perceptualRoughnessToMipmapLevel(0.0);  // Fixing incorrect mipmap level of cubemap texture
+
+                half4 skyData = UNITY_SAMPLE_TEXCUBE_LOD(unity_SpecCube0, boxProjection, mipLevel);
+                half3 skyColor = DecodeHDR(skyData, unity_SpecCube0_HDR);  // This is done becasue the cubemap is stored HDR
+
+                return half4(skyColor, 1.0);
+            }
+            ENDCG
+        }
+    }
+}