[Grass] adds grass bending when interacting with player (#37)

Assets/Materials/CubeGround/GrassCube.mat

@@ -95,6 +95,8 @@ Material:
     m_Floats:
     - _AlphaClip: 0
     - _AlphaToMask: 0
+    - _BendInfluenceRadius: 0.15
+    - _BendIntensity: 5
     - _BladeBendCurve: 2.07
     - _BladeBendDistance: 0.093
     - _BladeBendVariation: 0.368

Assets/Scenes/ForskarFredag.unity

@@ -2937,8 +2937,18 @@ PrefabInstance:
     m_RemovedComponents: []
     m_RemovedGameObjects: []
     m_AddedGameObjects: []
-    m_AddedComponents: []
+    m_AddedComponents:
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+        type: 3}
+      insertIndex: 5
+      addedObject: {fileID: 1933055332}
   m_SourcePrefab: {fileID: 100100000, guid: 77a7f27b58093f744a46d44c4ef7538b, type: 3}
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+  m_PrefabAsset: {fileID: 0}
 --- !u!1 &775372493
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@@ -5192,12 +5202,24 @@ MonoBehaviour:
     type: 3}
   m_PrefabInstance: {fileID: 769657836}
   m_PrefabAsset: {fileID: 0}
-  m_GameObject: {fileID: 0}
+  m_GameObject: {fileID: 769657837}
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   m_Script: {fileID: 11500000, guid: abb3402c4c18a074792eaf971efb46b1, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
+--- !u!114 &1933055332
+MonoBehaviour:
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+  m_Name: 
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   m_ObjectHideFlags: 0

Assets/Scripts/Player/PlayerPositionUpdater.cs

@@ -0,0 +1,13 @@
+using UnityEngine;
+
+public class PlayerPositionUpdater : MonoBehaviour
+{
+    void Update()
+    {
+        // Get the player's world position
+        Vector3 playerWorldPosition = transform.position;
+
+        // Update the _PlayerPosition uniform accessible from all shaders
+        Shader.SetGlobalVector("_PlayerPosition", playerWorldPosition);
+    }
+}

Assets/Shaders/URP_ProceduralGrass.shader

@@ -28,6 +28,10 @@ Shader "Universal Render Pipeline/Custom/ProceduralGrass"
         _WindFrequency("Wind Pulse Frequency", Range(0, 1)) = 0.01
         [NoScaleOffset]_WindMap("Wind Offset Map", 2D) = "bump" {}
 
+        [Space(10)][Header(# Player displacement)][Space(10)]
+        _BendIntensity("Bend Intensity", Range(0, 10)) = 3.0
+        _BendInfluenceRadius("Bend Influence Radius", Range(0, 0.5)) = 0.15
+
         [Space(10)][Header(# Lighting)][Space(10)]
         [Toggle(COMPUTE_LIGHTING)] _ComputeLighting("Compute Lighting", Float) = 0
         _ShadowIntensity("Shadow Intensity", Range(0, 1)) = 1.0
@@ -64,6 +68,10 @@ Shader "Universal Render Pipeline/Custom/ProceduralGrass"
             #define UNITY_TWO_PI 6.28318530718f
             #define BLADE_SEGMENTS 4
 
+            // -------------------------------------
+            // Global parameters
+            uniform float3 _PlayerPosition;
+
             // -------------------------------------
             // Material textures
             sampler2D _BladeTexture;
@@ -94,6 +102,9 @@ Shader "Universal Render Pipeline/Custom/ProceduralGrass"
                 float4 _WindMap_ST;
                 float4 _WindVelocity;
                 float  _WindFrequency;
+
+                float _BendIntensity;
+                float _BendInfluenceRadius;
             CBUFFER_END
 
             // -------------------------------------
@@ -358,9 +369,15 @@ Shader "Universal Render Pipeline/Custom/ProceduralGrass"
                 float3 windAxis = normalize(float3(windSample.x, windSample.y, 0));
                 float3x3 windMatrix = BuildRotationMatrix(UNITY_PI * windSample, windAxis);
 
+                // Apply player displacement.
+                float3 playerToBladeVector = origin - mul(unity_WorldToObject, _PlayerPosition);
+                float bendIntensity = _BendIntensity * smoothstep(_BendInfluenceRadius, 0.f, length(playerToBladeVector));
+                float3 bendAxis = normalize(float3(dot(playerToBladeVector, tangent), dot(playerToBladeVector, bitangent), 0));
+                float3x3 playerBendMatrix = BuildRotationMatrix(bendIntensity * UNITY_PI * 0.5f, bendAxis);
+
                 // Transform the grass blades to the correct tangent space.
                 float3x3 baseTransformationMatrix = mul(tangentToLocal, randRotMatrix);
-                float3x3 tipTransformationMatrix = mul(mul(mul(tangentToLocal, windMatrix), randBendMatrix), randRotMatrix);
+                float3x3 tipTransformationMatrix = mul(mul(mul(mul(tangentToLocal, windMatrix), playerBendMatrix), randBendMatrix), randRotMatrix);
 
                 float falloff = smoothstep(_GrassThreshold, _GrassThreshold + _GrassFalloff, grassVisibility);
                 float width = lerp(_BladeWidthMin, _BladeWidthMax, GenerateRandom(origin.xzy) * falloff) * _ShadowIntensity;
@@ -729,9 +746,15 @@ Shader "Universal Render Pipeline/Custom/ProceduralGrass"
                 float3 windAxis = normalize(float3(windSample.x, windSample.y, 0));
                 float3x3 windMatrix = BuildRotationMatrix(UNITY_PI * windSample, windAxis);
 
+                // Apply player displacement.
+                float3 playerToBladeVector = origin - mul(unity_WorldToObject, _PlayerPosition);
+                float bendIntensity = _BendIntensity * smoothstep(_BendInfluenceRadius, 0.f, length(playerToBladeVector));
+                float3 bendAxis = normalize(float3(dot(playerToBladeVector, tangent), dot(playerToBladeVector, bitangent), 0));
+                float3x3 playerBendMatrix = BuildRotationMatrix(bendIntensity * UNITY_PI * 0.5f, bendAxis);
+
                 // Transform the grass blades to the correct tangent space.
                 float3x3 baseTransformationMatrix = mul(tangentToLocal, randRotMatrix);
-                float3x3 tipTransformationMatrix = mul(mul(mul(tangentToLocal, windMatrix), randBendMatrix), randRotMatrix);
+                float3x3 tipTransformationMatrix = mul(mul(mul(mul(tangentToLocal, windMatrix), playerBendMatrix), randBendMatrix), randRotMatrix);
 
                 float falloff = smoothstep(_GrassThreshold, _GrassThreshold + _GrassFalloff, grassVisibility);
                 float width  = lerp(_BladeWidthMin, _BladeWidthMax, GenerateRandom(origin.xzy) * falloff);