From 54106962fefa85c3e1f89212a3be2036867bede2 Mon Sep 17 00:00:00 2001
From: MasTraER <mastraer@gmail.com>
Date: Fri, 29 Jul 2022 10:23:36 +0900
Subject: [PATCH] Fix incorrect precision restoration when computing accurate
 world translations

When FTransformManager computes accurate world transforms, it adds downcasted leftover to translation part to restore precision.
However, both transltation and leftover are given as float3 - simply adding them resut float3, so addling leftover become meaningless.
one or both should be upcasted first.
---
 RELEASE_NOTES.md                             | 1 +
 filament/src/components/TransformManager.cpp | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index 88d5246111..be82cc9d21 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -7,6 +7,7 @@ A new header is inserted each time a *tag* is created.
 
 - WebGL: upgraded the JS bindings to work with emsdk 3.1.15
 - WebGL: added missing IBL builder to TypeScript annotations
+- engine : Fix incorrect precision restoration when computing accurate world translations
 
 ## v1.25.4
 
diff --git a/filament/src/components/TransformManager.cpp b/filament/src/components/TransformManager.cpp
index 786845201a..2545e1eccb 100644
--- a/filament/src/components/TransformManager.cpp
+++ b/filament/src/components/TransformManager.cpp
@@ -412,10 +412,10 @@ void FTransformManager::computeWorldTransform(
 
         const mat4 ptd{
                 pt[0], pt[1], pt[2],
-                double4{ pt[3].xyz + ptTranslationLo, pt[3].w }};
+                double4{ double3(pt[3].xyz) + double3(ptTranslationLo), pt[3].w }};
 
         const double4 worldTranslation =
-                ptd * double4{ local[3].xyz + localTranslationLo, local[3].w };
+                ptd * double4{ double3(local[3].xyz) + double3(localTranslationLo), local[3].w };
 
         inoutWorldTranslationLo = worldTranslation.xyz - float3{ worldTranslation.xyz };
         outWorld[3] = worldTranslation;