From f2dba05568f5f53c6ae606a7e9da8371bede8501 Mon Sep 17 00:00:00 2001
From: Julius Krumbiegel <22495855+jkrumbiegel@users.noreply.github.com>
Date: Wed, 20 Dec 2023 11:01:18 +0100
Subject: [PATCH] Fix calculation of focal length for RPRMakie

---
 RPRMakie/src/scene.jl | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/RPRMakie/src/scene.jl b/RPRMakie/src/scene.jl
index 1e85771e6e2..65ff446771e 100644
--- a/RPRMakie/src/scene.jl
+++ b/RPRMakie/src/scene.jl
@@ -5,7 +5,6 @@ function update_rpr_camera!(oldvals, camera, cam_controls, cam)
     c = cam_controls
     l, u, p, fov = c.lookat[], c.upvector[], c.eyeposition[], c.fov[]
     far, near, res = c.far[], c.near[], cam.resolution[]
-    fov = 45f0 # The current camera ignores fov updates
     new_vals = (; l, u, p, fov, far, near, res)
     new_vals == oldvals && return oldvals
     wd = norm(l - p)
@@ -14,8 +13,8 @@ function update_rpr_camera!(oldvals, camera, cam_controls, cam)
     lookat!(camera, p, l, u)
     RPR.rprCameraSetFarPlane(camera, far)
     RPR.rprCameraSetNearPlane(camera, near)
-    h = norm(res)
-    RPR.rprCameraSetFocalLength(camera, (30*h)/fov)
+    focal_length = res[2] / (2 * tand(fov / 2)) # fov is vertical
+    RPR.rprCameraSetFocalLength(camera, focal_length)
     # RPR_CAMERA_FSTOP
     # RPR_CAMERA_MODE
     return new_vals