[Fogbugz # 1355839] Making Flare occlusion radius consistent for directional lights regardless of far plane

com.unity.render-pipelines.core/CHANGELOG.md

@@ -108,6 +108,7 @@ The version number for this package has increased due to a version update of a r
 - Improved IntegrateLDCharlie() to use uniform stratified sampling for faster convergence towards the ground truth
 - DynamicResolutionHandler.GetScaledSize function now clamps, and never allows to return a size greater than its input.
 - Removed DYNAMIC_RESOLUTION snippet on lens flare common shader. Its not necessary any more on HDRP, which simplifies the shader.
+- Made occlusion Radius for lens flares in directional lights, be independant of the camera's far plane.
 
 ## [11.0.0] - 2020-10-21
 

com.unity.render-pipelines.core/Runtime/PostProcessing/LensFlareCommonSRP.cs

@@ -422,8 +422,10 @@ static public void DoLensFlareDataDrivenCommon(Material lensFlareShader, LensFla
 
                 Vector3 dir = (cam.transform.position - comp.transform.position).normalized;
                 Vector3 screenPosZ = WorldToViewport(isCameraRelative, viewProjMatrix, cam.transform.position, positionWS + dir * comp.occlusionOffset);
+
+                float adjustedOcclusionRadius = isDirLight ? comp.celestialProjectedOcclusionRadius(cam) : comp.occlusionRadius;
                 Vector2 occlusionRadiusEdgeScreenPos0 = (Vector2)viewportPos;
-                Vector2 occlusionRadiusEdgeScreenPos1 = (Vector2)WorldToViewport(isCameraRelative, viewProjMatrix, cam.transform.position, positionWS + cam.transform.up * comp.occlusionRadius);
+                Vector2 occlusionRadiusEdgeScreenPos1 = (Vector2)WorldToViewport(isCameraRelative, viewProjMatrix, cam.transform.position, positionWS + cam.transform.up * adjustedOcclusionRadius);
                 float occlusionRadius = (occlusionRadiusEdgeScreenPos1 - occlusionRadiusEdgeScreenPos0).magnitude;
                 cmd.SetGlobalVector(_FlareData1, new Vector4(occlusionRadius, comp.sampleCount, screenPosZ.z, actualHeight / actualWidth));
 

com.unity.render-pipelines.core/Runtime/PostProcessing/LensFlareComponentSRP.cs

@@ -2,6 +2,8 @@
 using UnityEditor;
 #endif
 
+using System;
+
 namespace UnityEngine.Rendering
 {
     /// <summary>
@@ -90,6 +92,22 @@ public LensFlareDataSRP lensFlareData
         /// </summary>
         public bool allowOffScreen = false;
 
+        /// Our default celestial body will have an angular radius of 3.3 degrees. This is an arbitrary number, but must be kept constant
+        /// so the occlusion radius for direct lights is consistent regardless of near / far clip plane configuration.
+        private static float sCelestialAngularRadius = 3.3f * Mathf.PI / 180.0f;
+
+        /// <summary>
+        /// Retrieves the projected occlusion radius from a particular celestial in the infinity plane with an angular radius.
+        /// This is used for directional lights which require to have consistent occlusion radius regardless of the near/farplane configuration.
+        /// <param name="mainCam">The camera utilized to calculate the occlusion radius</param>
+        /// <return>The value, in world units, of the occlusion angular radius.</return>
+        /// </summary>
+        public float celestialProjectedOcclusionRadius(Camera mainCam)
+        {
+            float projectedRadius = (float)Math.Tan(sCelestialAngularRadius) * mainCam.farClipPlane;
+            return occlusionRadius * projectedRadius;
+        }
+
         /// <summary>
         /// Add or remove the lens flare to the queue of PostProcess
         /// </summary>
@@ -125,16 +143,19 @@ void OnValidate()
         }
 
 #if UNITY_EDITOR
+        private float sDebugClippingSafePercentage = 0.9f; //for debug gizmo, only push 90% further so we avoid clipping of debug lines.
         void OnDrawGizmosSelected()
         {
             Camera mainCam = Camera.current;
             if (mainCam != null && useOcclusion)
             {
                 Vector3 positionWS;
+                float adjustedOcclusionRadius = occlusionRadius;
                 Light light = GetComponent<Light>();
                 if (light != null && light.type == LightType.Directional)
                 {
-                    positionWS = -transform.forward * mainCam.farClipPlane + mainCam.transform.position;
+                    positionWS = -transform.forward * (mainCam.farClipPlane * sDebugClippingSafePercentage) + mainCam.transform.position;
+                    adjustedOcclusionRadius = celestialProjectedOcclusionRadius(mainCam);
                 }
                 else
                 {
@@ -146,7 +167,7 @@ void OnDrawGizmosSelected()
                 Handles.color = Color.red;
                 Gizmos.color = Color.red;
                 Vector3 dir = (mainCam.transform.position - positionWS).normalized;
-                Handles.DrawWireDisc(positionWS + dir * occlusionOffset, dir, occlusionRadius, 1.0f);
+                Handles.DrawWireDisc(positionWS + dir * occlusionOffset, dir, adjustedOcclusionRadius, 1.0f);
                 Gizmos.DrawWireSphere(positionWS, occlusionOffset);
                 Gizmos.color = previousG;
                 Handles.color = previousH;