Fix incorrect condition for GPUEvent

Mistake introduced at #4457

Author: PaulDemeulenaere

TestProjects/VisualEffectGraph_HDRP/Assets/AllTests/Editor/Tests/VFXContextTests.cs

@@ -203,6 +203,14 @@ public void Link_Fail_From_Event_To_OutputEvent()
             Assert.IsFalse(VFXContext.CanLink(from, to));
         }
 
+        [Test]
+        public void Link_Fail_From_GPUEvent_To_Spawn()
+        {
+            var from = ScriptableObject.CreateInstance<VFXBasicGPUEvent>();
+            var to = ScriptableObject.CreateInstance<VFXBasicSpawner>();
+            Assert.IsFalse(VFXContext.CanLink(from, to));
+        }
+
         [Test]
         public void MultiLink_Spawn_And_Event_To_Initialize()
         {

com.unity.visualeffectgraph/Editor/Models/Contexts/VFXContext.cs

@@ -260,8 +260,8 @@ public static bool CanLink(VFXContext from, VFXContext to, int fromIndex = 0, in
                 to.m_InputFlowSlot[toIndex].link.Any(o => o.context == from && o.slotIndex == fromIndex))
                 return false;
 
-            //Special incorrect case, GPUEvent use the same type than Spawner which leads to an unexpected allowed link.
-            if (from.m_ContextType == VFXContextType.SpawnerGPU && to.m_ContextType == VFXContextType.OutputEvent)
+            //Special incorrect case, GPUEvent use the same type than Spawner which leads to an unexpected allowed link on output & spawner.
+            if (from.m_ContextType == VFXContextType.SpawnerGPU && to.m_ContextType != VFXContextType.Init)
                 return false;
 
             //Can't connect directly event to context to OutputEvent