feat: gpu-based grid background

Assets/com.alelievr.NodeGraphProcessor/Editor/Shaders/Grid.shader

@@ -0,0 +1,74 @@
+Shader "GraphView/Grid"
+{
+    Properties
+    {
+        _GridColor ("Grid Color", Color) = (0.25, 0.25, 0.25, 1)
+        _BackgroundColor ("Background Color", Color) = (0.1, 0.1, 0.1, 1)
+        _GridSize ("Grid Size", Float) = 16.0
+        _ScaleLimit ("Upscale Limit", Int) = 4
+    }
+    SubShader
+    {
+        Tags { "RenderType" = "Opaque" }
+        LOD 200
+
+        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;
+                float scaleFactor : TEXCOORD1;
+            };
+
+            float4 _GridColor;
+            float _ScaleLimit;
+            float4 _BackgroundColor;
+            float4 _RtTransform;
+            float _Scale;
+            float _GridSize;
+
+            fixed4 grid(float2 uv, float scaleFactor)
+            {
+                float2 d = fwidth(uv);
+                float2 d2 = smoothstep(0.5 - d, 0.5, frac(uv + 0.5)) - smoothstep(0.5, 0.5 + d, frac(uv + 0.5));
+                return max(d2.x, d2.y) * smoothstep(0.1, 0.9, scaleFactor / _ScaleLimit);
+            }
+
+            v2f vert (appdata v)
+            {
+                v2f o;
+                o.vertex = UnityObjectToClipPos(v.vertex);
+                v.uv.y = 1 - v.uv.y;
+                float scale = pow(_ScaleLimit, frac(log(_Scale) / log(_ScaleLimit)));
+                o.uv = (v.uv * _RtTransform.xy - _RtTransform.zw) / _GridSize / scale;
+                o.scaleFactor = scale;
+                return o;
+            }
+
+            fixed4 frag (v2f i) : SV_Target
+            {
+                float2 uv = i.uv;
+                float scaleFactor = i.scaleFactor;
+                float weight = grid(uv, scaleFactor)
+                + grid(uv / _ScaleLimit, scaleFactor * _ScaleLimit);
+                fixed4 col = lerp(_BackgroundColor, _GridColor, weight);
+                return col;
+            }
+            ENDCG
+        }
+    }
+    FallBack "Diffuse"
+}

Assets/com.alelievr.NodeGraphProcessor/Editor/Views/BaseGraphView.cs

@@ -159,6 +159,8 @@ public BaseGraphView(EditorWindow window)
 			createNodeMenu = ScriptableObject.CreateInstance< CreateNodeMenuWindow >();
 			createNodeMenu.Initialize(this, window);
 
+			InitGrid();
+
 			this.StretchToParentSize();
 		}
 
@@ -686,6 +688,16 @@ void DragUpdatedCallback(DragUpdatedEvent e)
 
 		#region Initialization
 
+		void InitGrid()
+		{
+			var bgGrid = new GridView(contentViewContainer)
+			{
+				name = "GridView",
+			};
+			this.Add(bgGrid);
+			bgGrid.PlaceBehind(contentViewContainer);
+		}
+
 		void ReloadView()
 		{
 			// Force the graph to reload his data (Undo have updated the serialized properties of the graph

Assets/com.alelievr.NodeGraphProcessor/Editor/Views/GridView.cs

@@ -0,0 +1,81 @@
+using UnityEditor;
+using UnityEngine;
+using UnityEngine.UIElements;
+
+namespace GraphProcessor
+{
+    public class GridView : VisualElement
+    {
+        private static readonly int ID_RT_TRANSFORM = Shader.PropertyToID("_RtTransform");
+        private static readonly int ID_SCALE = Shader.PropertyToID("_Scale");
+
+        private Material material;
+        private RenderTexture renderTexture;
+        private VisualElement transformSource;
+
+        public GridView()
+        {
+
+        }
+
+        public GridView(VisualElement transformSource)
+        {
+            this.transformSource = transformSource;
+
+            RegisterCallback<AttachToPanelEvent>(OnAttachToPanel);
+            RegisterCallback<DetachFromPanelEvent>(OnDetachFromPanel);
+
+            style.position = Position.Absolute;
+            style.backgroundSize = new BackgroundSize(BackgroundSizeType.Cover);
+            style.width = new Length(Screen.currentResolution.width, LengthUnit.Pixel);
+            style.height = new Length(Screen.currentResolution.height, LengthUnit.Pixel);
+        }
+
+        private void OnAttachToPanel(AttachToPanelEvent e)
+        {
+            renderTexture = RenderTexture.GetTemporary(
+                Screen.currentResolution.width,
+                Screen.currentResolution.height,
+                0, RenderTextureFormat.ARGB32,
+                RenderTextureReadWrite.Default);
+            renderTexture.Create();
+            material = new Material(Shader.Find("GraphView/Grid"));
+            style.backgroundImage = Background.FromRenderTexture(renderTexture);
+
+            Redraw();
+
+            EditorApplication.update -= Redraw;
+            EditorApplication.update += Redraw;
+        }
+
+        private void Redraw()
+        {
+            if (transformSource == null || renderTexture == null || material == null)
+                return;
+
+            material.SetVector(ID_RT_TRANSFORM, new Vector4(
+                Screen.currentResolution.width, Screen.currentResolution.height,
+                transformSource.resolvedStyle.translate.x, transformSource.resolvedStyle.translate.y
+            ));
+            material.SetFloat(ID_SCALE, transformSource.resolvedStyle.scale.value.x);
+            Graphics.SetRenderTarget(renderTexture);
+            Graphics.Blit(null, material);
+        }
+
+        private void OnDetachFromPanel(DetachFromPanelEvent e)
+        {
+            if (renderTexture)
+            {
+                RenderTexture.ReleaseTemporary(renderTexture);
+            }
+
+            if (material)
+            {
+                Object.DestroyImmediate(material);
+            }
+
+            style.backgroundImage = null;
+            EditorApplication.update -= Redraw;
+        }
+    }
+}