Better handling for excessproximity lights (#10241)

Previously, if the shader's maximum proximity light limit was reached, a warning would be logged and the lights discarded. I've changed this to keep all lights around on the CPU side and only send the first two valid ones to the shader. This helps with race conditions where multiple lights are added and removed in a single frame and eliminates a warning that was spamming to the log and degrading performance.

Co-authored-by: Roger Liu <[email protected]>

Author: jonathoncobb

Assets/MRTK/Core/Utilities/StandardShader/ProximityLight.cs

@@ -9,18 +9,21 @@
 namespace Microsoft.MixedReality.Toolkit.Utilities
 {
     /// <summary>
-    /// Utility component to animate and visualize a light that can be used with 
+    /// Utility component to animate and visualize a light that can be used with
     /// the "MixedRealityToolkit/Standard" shader "_ProximityLight" feature.
     /// </summary>
     [ExecuteInEditMode]
     [HelpURL("https://docs.microsoft.com/windows/mixed-reality/mrtk-unity/features/rendering/proximity-light")]
     [AddComponentMenu("Scripts/MRTK/Core/ProximityLight")]
     public class ProximityLight : MonoBehaviour
     {
-        // Two proximity lights are supported at this time.
+        // Two proximity lights are supported at this time. Excess lights will
+        // be held in a queue and addded to the shader in a first-in, first-out
+        // manner.
         private const int proximityLightCount = 2;
+        private const int proximityLightQueueSize = 6;
         private const int proximityLightDataSize = 6;
-        private static List<ProximityLight> activeProximityLights = new List<ProximityLight>(proximityLightCount);
+        private static List<ProximityLight> activeProximityLights = new List<ProximityLight>(proximityLightQueueSize);
         private static Vector4[] proximityLightData = new Vector4[proximityLightCount * proximityLightDataSize];
         private static int proximityLightDataID;
         private static int lastProximityLightUpdate = -1;
@@ -213,11 +216,6 @@ private void OnDrawGizmosSelected()
 
         private static void AddProximityLight(ProximityLight light)
         {
-            if (activeProximityLights.Count >= proximityLightCount)
-            {
-                Debug.LogWarningFormat("Max proximity light count ({0}) exceeded.", proximityLightCount);
-            }
-
             activeProximityLights.Add(light);
         }
 
@@ -243,13 +241,15 @@ private static void UpdateProximityLights(bool forceUpdate = false)
                 return;
             }
 
-            for (int i = 0; i < proximityLightCount; ++i)
+            int lightIndex, queueIndex;
+            for (lightIndex = queueIndex = 0; queueIndex < activeProximityLights.Count && lightIndex < proximityLightCount; ++queueIndex)
             {
-                ProximityLight light = (i >= activeProximityLights.Count) ? null : activeProximityLights[i];
-                int dataIndex = i * proximityLightDataSize;
+                ProximityLight light = activeProximityLights[queueIndex];
 
                 if (light)
                 {
+                    int dataIndex = lightIndex++ * proximityLightDataSize;
+
                     proximityLightData[dataIndex] = new Vector4(light.transform.position.x,
                                                                 light.transform.position.y,
                                                                 light.transform.position.z,
@@ -267,10 +267,12 @@ private static void UpdateProximityLights(bool forceUpdate = false)
                     proximityLightData[dataIndex + 4] = light.Settings.MiddleColor;
                     proximityLightData[dataIndex + 5] = light.Settings.OuterColor;
                 }
-                else
-                {
-                    proximityLightData[dataIndex] = Vector4.zero;
-                }
+            }
+
+            for (; lightIndex < proximityLightCount; ++lightIndex)
+            {
+                int dataIndex = lightIndex * proximityLightDataSize;
+                proximityLightData[dataIndex] = Vector4.zero;
             }
 
             Shader.SetGlobalVectorArray(proximityLightDataID, proximityLightData);