From 18d723b6b43b62f57ddeaf362bcc95ebf1afa261 Mon Sep 17 00:00:00 2001
From: "Anthony J. Thibault" <tony@highfidelity.io>
Date: Tue, 10 Oct 2017 16:17:39 -0700
Subject: [PATCH] div by zero fixes, detected by address sanitizer

---
 interface/src/LODManager.cpp                              | 1 +
 libraries/animation/src/Rig.cpp                           | 7 ++++++-
 .../avatars-renderer/src/avatars-renderer/Avatar.cpp      | 3 ++-
 libraries/shared/src/MovingMinMaxAvg.h                    | 8 ++++++--
 4 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/interface/src/LODManager.cpp b/interface/src/LODManager.cpp
index d3c8746e16..199f3ea2c6 100644
--- a/interface/src/LODManager.cpp
+++ b/interface/src/LODManager.cpp
@@ -54,6 +54,7 @@ void LODManager::autoAdjustLOD(float batchTime, float engineRunTime, float delta
     float renderTime = batchTime + OVERLAY_AND_SWAP_TIME_BUDGET;
     float maxTime = glm::max(renderTime, engineRunTime);
     const float BLEND_TIMESCALE = 0.3f; // sec
+    const float safeDeltaTime = (deltaTime == 0.0f) ? 0.001f : deltaTime;
     float blend = BLEND_TIMESCALE / deltaTimeSec;
     if (blend > 1.0f) {
         blend = 1.0f;
diff --git a/libraries/animation/src/Rig.cpp b/libraries/animation/src/Rig.cpp
index 0897c26a12..83d258fb08 100644
--- a/libraries/animation/src/Rig.cpp
+++ b/libraries/animation/src/Rig.cpp
@@ -38,7 +38,12 @@ static std::mutex rigRegistryMutex;
 
 static bool isEqual(const glm::vec3& u, const glm::vec3& v) {
     const float EPSILON = 0.0001f;
-    return glm::length(u - v) / glm::length(u) <= EPSILON;
+    float uLen = glm::length(u);
+    if (uLen == 0.0f) {
+        return glm::length(v) <= EPSILON;
+    } else {
+        return glm::length(u - v) / glm::length(u) <= EPSILON;
+    }
 }
 
 static bool isEqual(const glm::quat& p, const glm::quat& q) {
diff --git a/libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp b/libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp
index 87d4a2d343..a52582ff45 100644
--- a/libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp
+++ b/libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp
@@ -446,7 +446,8 @@ void Avatar::applyPositionDelta(const glm::vec3& delta) {
 void Avatar::measureMotionDerivatives(float deltaTime) {
     PerformanceTimer perfTimer("derivatives");
     // linear
-    float invDeltaTime = 1.0f / deltaTime;
+    const float safeDeltaTime = (deltaTime == 0.0f) ? 0.001f : deltaTime;
+    float invDeltaTime = 1.0f / safeDeltaTime;
     // Floating point error prevents us from computing velocity in a naive way
     // (e.g. vel = (pos - oldPos) / dt) so instead we use _positionOffsetAccumulator.
     glm::vec3 velocity = _positionDeltaAccumulator * invDeltaTime;
diff --git a/libraries/shared/src/MovingMinMaxAvg.h b/libraries/shared/src/MovingMinMaxAvg.h
index 580baf7317..782b0dc523 100644
--- a/libraries/shared/src/MovingMinMaxAvg.h
+++ b/libraries/shared/src/MovingMinMaxAvg.h
@@ -59,8 +59,12 @@ public:
             _max = other._max;
         }
         double totalSamples = _samples + other._samples;
-        _average = _average * ((double)_samples / totalSamples)
-            + other._average * ((double)other._samples / totalSamples);
+        if (totalSamples > 0) {
+            _average = _average * ((double)_samples / totalSamples)
+                + other._average * ((double)other._samples / totalSamples);
+        } else {
+            _average = 0.0f;
+        }
         _samples += other._samples;
     }