From 29485b65e568a22b6799d38db2a620c0654171b3 Mon Sep 17 00:00:00 2001
From: Olivier Prat <olivier@zvork.fr>
Date: Fri, 22 Dec 2017 14:35:19 +0100
Subject: [PATCH] Fixed potential crash when getting mesh from voxel item

---
 .../src/RenderablePolyVoxEntityItem.cpp       | 44 ++++++++++---------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/libraries/entities-renderer/src/RenderablePolyVoxEntityItem.cpp b/libraries/entities-renderer/src/RenderablePolyVoxEntityItem.cpp
index 356bf3a69c..2078f7abee 100644
--- a/libraries/entities-renderer/src/RenderablePolyVoxEntityItem.cpp
+++ b/libraries/entities-renderer/src/RenderablePolyVoxEntityItem.cpp
@@ -1422,27 +1422,29 @@ bool RenderablePolyVoxEntityItem::getMeshes(MeshProxyList& result) {
     }
 
     bool success = false;
-    MeshProxy* meshProxy = nullptr;
-    glm::mat4 transform = voxelToLocalMatrix();
-    withReadLock([&] {
-        gpu::BufferView::Index numVertices = (gpu::BufferView::Index)_mesh->getNumVertices();
-        if (!_meshReady) {
-            // we aren't ready to return a mesh.  the caller will have to try again later.
-            success = false;
-        } else if (numVertices == 0) {
-            // we are ready, but there are no triangles in the mesh.
-            success = true;
-        } else {
-            success = true;
-            // the mesh will be in voxel-space.  transform it into object-space
-            meshProxy = new SimpleMeshProxy(
-                _mesh->map([=](glm::vec3 position){ return glm::vec3(transform * glm::vec4(position, 1.0f)); },
-                           [=](glm::vec3 color){ return color; },
-                           [=](glm::vec3 normal){ return glm::normalize(glm::vec3(transform * glm::vec4(normal, 0.0f))); },
-                           [&](uint32_t index){ return index; }));
-            result << meshProxy;
-        }
-    });
+    if (_mesh) {
+        MeshProxy* meshProxy = nullptr;
+        glm::mat4 transform = voxelToLocalMatrix();
+        withReadLock([&] {
+            gpu::BufferView::Index numVertices = (gpu::BufferView::Index)_mesh->getNumVertices();
+            if (!_meshReady) {
+                // we aren't ready to return a mesh.  the caller will have to try again later.
+                success = false;
+            } else if (numVertices == 0) {
+                // we are ready, but there are no triangles in the mesh.
+                success = true;
+            } else {
+                success = true;
+                // the mesh will be in voxel-space.  transform it into object-space
+                meshProxy = new SimpleMeshProxy(
+                    _mesh->map([=](glm::vec3 position) { return glm::vec3(transform * glm::vec4(position, 1.0f)); },
+                    [=](glm::vec3 color) { return color; },
+                    [=](glm::vec3 normal) { return glm::normalize(glm::vec3(transform * glm::vec4(normal, 0.0f))); },
+                    [&](uint32_t index) { return index; }));
+                result << meshProxy;
+            }
+        });
+    }
     return success;
 }