From 5bade2ef9aabb89dc4f9e63d420afabfb6c1e057 Mon Sep 17 00:00:00 2001
From: Brad Davis <bdavis@saintandreas.org>
Date: Thu, 1 Dec 2016 14:09:36 -0800
Subject: [PATCH] Add locking around the code that reads polyline entity data
 and builds GPU structures for them

---
 .../src/RenderablePolyLineEntityItem.cpp            | 13 +++++++++----
 .../src/RenderablePolyLineEntityItem.h              |  1 +
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/libraries/entities-renderer/src/RenderablePolyLineEntityItem.cpp b/libraries/entities-renderer/src/RenderablePolyLineEntityItem.cpp
index 286efb5fb8..4c1f21adb6 100644
--- a/libraries/entities-renderer/src/RenderablePolyLineEntityItem.cpp
+++ b/libraries/entities-renderer/src/RenderablePolyLineEntityItem.cpp
@@ -161,8 +161,14 @@ void RenderablePolyLineEntityItem::update(const quint64& now) {
     uniforms.color = toGlm(getXColor());
     memcpy(&_uniformBuffer.edit<PolyLineUniforms>(), &uniforms, sizeof(PolyLineUniforms));
     if (_pointsChanged || _strokeWidthsChanged || _normalsChanged) {
-        updateVertices();
-        updateGeometry();
+        QWriteLocker lock(&_quadReadWriteLock);
+        if (_points.size() < 2 || _normals.size() < 2 || _strokeWidths.size() < 2) {
+            _empty = true;
+        }
+        if (!_empty) {
+            updateVertices();
+            updateGeometry();
+        }
     }
 
 }
@@ -170,8 +176,7 @@ void RenderablePolyLineEntityItem::update(const quint64& now) {
 void RenderablePolyLineEntityItem::render(RenderArgs* args) {
     checkFading();
 
-    QWriteLocker lock(&_quadReadWriteLock);
-    if (_points.size() < 2 || _normals.size () < 2 || _strokeWidths.size() < 2) {
+    if (_empty) {
         return;
     }
 
diff --git a/libraries/entities-renderer/src/RenderablePolyLineEntityItem.h b/libraries/entities-renderer/src/RenderablePolyLineEntityItem.h
index 44b29bdec1..eca6b7035a 100644
--- a/libraries/entities-renderer/src/RenderablePolyLineEntityItem.h
+++ b/libraries/entities-renderer/src/RenderablePolyLineEntityItem.h
@@ -50,6 +50,7 @@ protected:
     gpu::BufferPointer _verticesBuffer;
     gpu::BufferView _uniformBuffer;
     unsigned int _numVertices;
+    bool _empty { true };
     QVector<glm::vec3> _vertices;
 };