Merge pull request #377 from Unity-Technologies/Branch_FixShadowAtlasException

Failing to allocate shadow maps no longer throws an exception but just raises an error.

Assets/ScriptableRenderPipeline/Core/Shadow/Shadow.cs

             ShadowDataVector shadowVector = m_ShadowCtxt.shadowDatas;
             ShadowPayloadVector payloadVector = m_ShadowCtxt.payloads;
             m_ShadowIndices.Reset( m_TmpRequests.Count() );
-            AllocateShadows( frameId, camera, cameraRelativeRendering, lights, totalGranted, ref m_TmpRequests, ref m_ShadowIndices, ref shadowVector, ref payloadVector );
+            if (!AllocateShadows(frameId, camera, cameraRelativeRendering, lights, totalGranted, ref m_TmpRequests, ref m_ShadowIndices, ref shadowVector, ref payloadVector))
+            {
+                shadowRequestsCount = 0;
+                return;
+            }
             Debug.Assert( m_TmpRequests.Count() == m_ShadowIndices.Count() );
             m_ShadowCtxt.shadowDatas = shadowVector;
             m_ShadowCtxt.payloads = payloadVector;
             m_TmpSortKeys.ExtractTo( ref shadowRequests, (long idx) => { return (int) idx; } );
         }
 
-        protected override void AllocateShadows( FrameId frameId, Camera camera, bool cameraRelativeRendering, List<VisibleLight> lights, uint totalGranted, ref ShadowRequestVector grantedRequests, ref ShadowIndicesVector shadowIndices, ref ShadowDataVector shadowDatas, ref ShadowPayloadVector shadowmapPayload )
+        protected override bool AllocateShadows( FrameId frameId, Camera camera, bool cameraRelativeRendering, List<VisibleLight> lights, uint totalGranted, ref ShadowRequestVector grantedRequests, ref ShadowIndicesVector shadowIndices, ref ShadowDataVector shadowDatas, ref ShadowPayloadVector shadowmapPayload )
         {
             ShadowData sd = new ShadowData();
             shadowDatas.Reserve( totalGranted );
                     smidx++;
                 }
                 if( smidx == k_MaxShadowmapPerType )
-                    throw new ArgumentException("The requested shadows do not fit into any shadowmap.");
+                {
+                    Debug.LogError("The requested shadows do not fit into any shadowmap.");
+                    return false;
+                }
             }
 
             // final step for shadowmaps that only gather data during the previous loop and do the actual allocation once they have all the data.
-                    throw new ArgumentException( "Shadow allocation failed in the ReserveFinalize step." );
+                {
+                    Debug.LogError("Shadow allocation failed in the ReserveFinalize step." );
+                    return false;
+                }
+
+            return true;
         }
 
         public override void RenderShadows( FrameId frameId, ScriptableRenderContext renderContext, CommandBuffer cmd, CullResults cullResults, List<VisibleLight> lights)

Assets/ScriptableRenderPipeline/Core/Shadow/ShadowBase.cs

         // prune the shadow requests - may modify shadowRequests and shadowsCountshadowRequestsCount
         protected abstract void PruneShadowCasters( Camera camera, List<VisibleLight> lights, ref VectorArray<int> shadowRequests, ref VectorArray<ShadowmapBase.ShadowRequest> requestsGranted, out uint totalRequestCount );
         // allocate the shadow requests in the shadow map, only is called if shadowsCount > 0 - may modify shadowRequests and shadowsCount
-        protected abstract void AllocateShadows( FrameId frameId, Camera camera, bool cameraRelativeRendering, List<VisibleLight> lights, uint totalGranted, ref VectorArray<ShadowmapBase.ShadowRequest> grantedRequests, ref VectorArray<int> shadowIndices, ref VectorArray<ShadowData> shadowmapDatas, ref VectorArray<ShadowPayload> shadowmapPayload );
+        protected abstract bool AllocateShadows( FrameId frameId, Camera camera, bool cameraRelativeRendering, List<VisibleLight> lights, uint totalGranted, ref VectorArray<ShadowmapBase.ShadowRequest> grantedRequests, ref VectorArray<int> shadowIndices, ref VectorArray<ShadowData> shadowmapDatas, ref VectorArray<ShadowPayload> shadowmapPayload );
 
         public abstract uint GetShadowMapCount();
         public abstract uint GetShadowMapSliceCount(uint shadowMapIndex);