SL-17449 Fix for Alexa's hair

indra/newview/llspatialpartition.h

@@ -255,6 +255,19 @@ public:
 		}
 	};
 
+    struct CompareRenderOrder
+    {
+        bool operator()(const LLSpatialGroup* const& lhs, const LLSpatialGroup* const& rhs)
+        {
+            if (lhs->mAvatarp != rhs->mAvatarp)
+            {
+                return lhs->mAvatarp < rhs->mAvatarp;
+            }
+
+            return lhs->mRenderOrder > rhs->mRenderOrder;
+        }
+    };
+
 	typedef enum
 	{
 		GEOM_DIRTY				= LLViewerOctreeGroup::INVALID_STATE,
@@ -338,6 +351,10 @@ public:
 	
 	F32 mPixelArea;
 	F32 mRadius;
+
+    //used by LLVOAVatar to set render order in alpha draw pool to preserve legacy render order behavior
+    LLVOAvatar* mAvatarp = nullptr;
+    U32 mRenderOrder = 0; 
 } LL_ALIGN_POSTFIX(64);
 
 class LLGeometryManager

indra/newview/llvoavatar.cpp

@@ -2809,6 +2809,7 @@ void LLVOAvatar::idleUpdateMisc(bool detailed_update)
 	// update attachments positions
 	if (detailed_update)
 	{
+        U32 draw_order = 0;
 		for (attachment_map_t::iterator iter = mAttachmentPoints.begin(); 
 			 iter != mAttachmentPoints.end();
 			 ++iter)
@@ -2875,6 +2876,13 @@ void LLVOAvatar::idleUpdateMisc(bool detailed_update)
                             bridge->setState(LLDrawable::MOVE_UNDAMPED);
                             bridge->updateMove();
                             bridge->setState(LLDrawable::EARLY_MOVE);
+
+                            LLSpatialGroup* group = attached_object->mDrawable->getSpatialGroup();
+                            if (group)
+                            { //set draw order of group
+                                group->mAvatarp = this;
+                                group->mRenderOrder = draw_order++;
+                            }
                         }
                     }
 

indra/newview/pipeline.cpp

@@ -3877,7 +3877,11 @@ void LLPipeline::postSort(LLCamera& camera)
 
 	if (!sShadowRender)
 	{
+        // order alpha groups by distance
 		std::sort(sCull->beginAlphaGroups(), sCull->endAlphaGroups(), LLSpatialGroup::CompareDepthGreater());
+
+        // order rigged alpha groups by avatar attachment order
+        std::sort(sCull->beginRiggedAlphaGroups(), sCull->endRiggedAlphaGroups(), LLSpatialGroup::CompareRenderOrder());
 	}
 
 	LL_PUSH_CALLSTACKS();