Edge direction visualization via shader

.vscode/settings.json

@@ -39,7 +39,6 @@
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         "**/*.cubemap": true,
         "**/*.flare": true,
-        "**/*.mat": true,
         "**/*.meta": true,
         "build/": true,
         "Build/": true,

Assets/Resources/Materials/TransparentEdgePortalMaterial.mat

@@ -0,0 +1,92 @@
+%YAML 1.1
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+--- !u!21 &2100000
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+    - _AnimationPause: 0.4
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+    - _EffectWidth: 0.03
+    - _GlossMapScale: 1
+    - _Glossiness: 0.5
+    - _GlossyReflections: 1
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Assets/Resources/Materials/TransparentEdgePortalMaterial.mat.meta

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Assets/Resources/Shaders/TransparentEdgePortalShader.shader

@@ -0,0 +1,127 @@
+Shader "Unlit/SEE/TransparentEdgePortalShader"
+{
+    Properties
+    {
+        // Color
+        _Color("(Start) Color", color) = (1,0,0,1)
+        _EndColor("End Color", color) = (0,0,1,1)
+        _ColorGradientEnabled("Enable Color Gradient?", Range(0, 1)) = 0 // 0 = false, 1 = true
+
+        // Data Flow
+        _EdgeFlowEnabled("Enable Data Flow Visualization?", Range(0, 1)) = 0 // 0 = false, 1 = true
+        _AnimationFactor("Animation Speed Factor", Range(0, 3)) = 0.4
+        _AnimationPause("Pause Between Animations", Range(0, 3)) = 0.4
+        _EffectWidth("Effect Width", Range(0, 1.0)) = 0.03
+        _GrowthAmount("Growth Amount", Range(0, 0.04)) = 0.005
+
+        // Clipping
+        _PortalMin("Portal Left Front Corner", vector) = (-10, -10, 0, 0)
+        _PortalMax("Portal Right Back Corner", vector) = (10, 10, 0, 0)
+    }
+    SubShader
+    {
+        Tags {
+            "Queue"="Transparent"
+            "RenderType"="Transparent"
+            "IgnoreProjector"="True"
+            "ForceNoShadowCasting" = "True"
+            "PreviewType" = "Plane"
+        }
+
+        // Alpha blending mode for transparency
+        Blend SrcAlpha OneMinusSrcAlpha
+        // Do not write to depth buffer to allow transparency effect
+        // Note: We will be able to see parts of the edge through other parts of the same edge, that should be occluded
+        //       on full opacity. This is not a desired effect but not a big issue either.
+        ZWrite Off
+        // Makes the inside visible at clipping planes
+        Cull Off
+        // Unity's lighting will not be applied
+        Lighting Off
+
+        Pass
+        {
+            CGPROGRAM
+            #pragma vertex vert
+            #pragma fragment frag
+
+            #include "UnityCG.cginc"
+
+            struct appdata
+            {
+                float4 vertex : POSITION;
+                float3 normal : NORMAL;
+                float2 uv : TEXCOORD0;
+            };
+
+            struct v2f
+            {
+                float4 vertex : SV_POSITION;
+                float3 worldPos : TEXCOORD0;
+                float2 uv : TEXCOORD1;
+            };
+
+            // Color
+            fixed4 _Color;
+            fixed4 _EndColor;
+            float _ColorGradientEnabled;
+
+            // Data Flow
+            float _EdgeFlowEnabled;
+            float _AnimationFactor;
+            float _AnimationPause;
+            float _EffectWidth;
+            float _GrowthAmount;
+
+            // Clipping
+            float2 _PortalMin;
+            float2 _PortalMax;
+
+            v2f vert (appdata v)
+            {
+                v2f o;
+
+                if (_EdgeFlowEnabled > 0.5)
+                {
+                    // The effect is supposed to move automatically based on the time and the animation factor.
+                    // The position is calculated based on the assumption that the object has a uniform UV mapping (0.0 to 1.0 along the y axis).
+                    // We stretch the effect scale by the effect width so that the effect fades in and out smoothly at both ends, respectively.
+                    // Additionally, the effect scale is stretched to add a pause between the animations.
+                    float effectPosition = frac(_Time.y * _AnimationFactor) * (1.0 + 2 * _EffectWidth + _AnimationPause) - _EffectWidth;
+
+                    // Distance between the vertex and the effect position on the y axis in world-space
+                    float distance = abs(v.uv.y - effectPosition);
+
+                    if (distance < _EffectWidth)
+                    {
+                        // The effect strength is based on the distance to the effect position
+                        float effectFactor = 1.0 - pow(distance / _EffectWidth, 3);
+                        effectFactor = clamp(effectFactor, 0.0, 1.0);
+                        // We use the direction of the normal to grow outward
+                        float3 outwardDir = normalize(v.normal);
+                        v.vertex.xyz += outwardDir * effectFactor * _GrowthAmount;
+                    }
+                }
+
+                o.vertex = UnityObjectToClipPos(v.vertex);
+                o.worldPos = mul(unity_ObjectToWorld, v.vertex);
+                o.uv = v.uv;
+                return o;
+            }
+
+            fixed4 frag (v2f i) : SV_Target
+            {
+                // Clipping
+                // Note: We use a 2D portal (x, y) that spans over a (x, z) plane in the Unity 3D space.
+                if (i.worldPos.x < _PortalMin.x || i.worldPos.x > _PortalMax.x ||
+                    i.worldPos.z < _PortalMin.y || i.worldPos.z > _PortalMax.y)
+                {
+                    discard;
+                }
+
+                return _ColorGradientEnabled > 0.5 ? lerp(_Color, _EndColor, i.uv.y) : _Color;
+            }
+            ENDCG
+        }
+    }
+}

Assets/Resources/Shaders/TransparentEdgePortalShader.shader.meta

@@ -0,0 +1,9 @@
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