From 39cbef1e21c2910366e58d28f2d955030e04bac6 Mon Sep 17 00:00:00 2001
From: shimaowo <45767709+shimaowo@users.noreply.github.com>
Date: Mon, 16 Jan 2023 11:39:13 -0800
Subject: [PATCH] Fix: fix incorrect math for calculating the horizontal FOV of
 a perspective camera in GLTF2 import #4435

---
 code/AssetLib/glTF2/glTF2Importer.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/code/AssetLib/glTF2/glTF2Importer.cpp b/code/AssetLib/glTF2/glTF2Importer.cpp
index 7d3a4b9fe..0cf5472d6 100644
--- a/code/AssetLib/glTF2/glTF2Importer.cpp
+++ b/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -853,7 +853,7 @@ void glTF2Importer::ImportCameras(glTF2::Asset &r) {
 
         if (cam.type == Camera::Perspective) {
             aicam->mAspect = cam.cameraProperties.perspective.aspectRatio;
-            aicam->mHorizontalFOV = cam.cameraProperties.perspective.yfov * ((aicam->mAspect == 0.f) ? 1.f : aicam->mAspect);
+            aicam->mHorizontalFOV = 2.0f * std::atan(std::tan(cam.cameraProperties.perspective.yfov * 0.5f) * (aicam->mAspect == 0.f) ? 1.f : aicam->mAspect);
             aicam->mClipPlaneFar = cam.cameraProperties.perspective.zfar;
             aicam->mClipPlaneNear = cam.cameraProperties.perspective.znear;
         } else {