1 files changed, 77 insertions, 0 deletions
diff --git a/Scripts/GrassGridBlit.shader b/Scripts/GrassGridBlit.shader
new file mode 100644
index 0000000..f4dc872
--- /dev/null
+++ b/Scripts/GrassGridBlit.shader
@@ -0,0 +1,77 @@
+Shader "yum_food/GrassGridBlit"
+{
+    Properties
+    {
+    }
+    SubShader
+    {
+        Tags { "RenderType"="Opaque" }
+        LOD 100
+
+        Pass
+        {
+            CGPROGRAM
+            #pragma vertex vert
+            #pragma fragment frag
+
+            #include "UnityCG.cginc"
+
+            struct appdata
+            {
+                float4 vertex : POSITION;
+                float2 uv : TEXCOORD0;
+            };
+
+            struct v2f
+            {
+                float2 uv : TEXCOORD0;
+                float4 vertex : SV_POSITION;
+            };
+
+            // Grid parameters
+            float3 _PlayerGridPos;    // Player's grid cell position (x, y, z)
+            int3 _GridCount;          // Number of instances along each axis
+            int3 _GridHalf;           // Half dimensions for centering around player
+            int2 _TexDimensions;      // Texture width and height
+
+            v2f vert (appdata v)
+            {
+                v2f o;
+                o.vertex = UnityObjectToClipPos(v.vertex);
+                o.uv = v.uv;
+                return o;
+            }
+
+            float4 frag (v2f i) : SV_Target
+            {
+                // Convert UV to pixel coordinates
+                int2 pixelCoord = int2(i.uv.x * _TexDimensions.x, i.uv.y * _TexDimensions.y);
+
+                // Convert pixel coordinate to instance index
+                int instanceID = pixelCoord.x + pixelCoord.y * _TexDimensions.x;
+
+                // Calculate total valid instances
+                int totalInstances = _GridCount.x * _GridCount.y * _GridCount.z;
+
+                // If this pixel is beyond valid instances, output invalid marker
+                if (instanceID >= totalInstances) {
+                    return float4(0, 0, 0, -1);  // Alpha = -1 marks invalid
+                }
+
+                // Convert instance index to local grid coordinates (0 to GridCount-1)
+                int localX = instanceID % _GridCount.x;
+                int localY = (instanceID / _GridCount.x) % _GridCount.y;
+                int localZ = instanceID / (_GridCount.x * _GridCount.y);
+
+                // Convert to world grid coordinates centered around player
+                int worldX = _PlayerGridPos.x - _GridHalf.x + localX;
+                int worldY = _PlayerGridPos.y - _GridHalf.y + localY;
+                int worldZ = _PlayerGridPos.z - _GridHalf.z + localZ;
+
+                // Store world grid coordinates in RGB channels, alpha = 0 marks valid
+                return float4(worldX, worldY, worldZ, 0);
+            }
+            ENDCG
+        }
+    }
+}