From b739d9a411badb9f76fce084b7158757fb339506 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Mon, 30 Jun 2025 18:19:20 +0100
Subject: [PATCH] experiment: smooth orientation a bit

remember three most recent orientation values and pick the middle one
but clamped between the values of the least and most recent
---
 pkgs/maps/main.fnl | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/pkgs/maps/main.fnl b/pkgs/maps/main.fnl
index c8e79c8..67a6e76 100644
--- a/pkgs/maps/main.fnl
+++ b/pkgs/maps/main.fnl
@@ -86,6 +86,7 @@ label.readout {
             :lon 0
             :zoom 17
             :course 0 ; direction of travel
+            :courses [0 0 0]
             :orientation-target 0  ; map rotation angle from north
             :orientation-actual 0  ; map rotation angle from north
             :tiles {}
@@ -446,6 +447,11 @@ label.readout {
                  }))))
 
 
+(fn clamp [a b c]
+  (if (< b a) a
+      (> b c) c
+      b))
+
 (fn read-gnss [socket]
   (each [l #(socket:read "l")]
     ; (print "gnss" l)
@@ -463,9 +469,14 @@ label.readout {
              )
             { : speed-knots }
             (update-app-state { :speed (* speed-knots knot-in-m-s) }))
-          (if message.bearing-true
-              (update-app-state { :course message.bearing-true }))
-          )))
+          (when message.bearing-true
+            (let [c1 message.bearing-true
+                  c2 (. app-state.courses 1)
+                  c3 (. app-state.courses 2)]
+              (update-app-state
+               { :course (clamp c1 c2 c3)
+                 :courses [c1 c2 c3]
+                 }))))))
   true)
 
 (fn collect-profile []