From d25924b571acd83b99dcb2bd4607a5f2b8564ba1 Mon Sep 17 00:00:00 2001
From: Ryan Friedman <ryan.friedman@avinc.com>
Date: Wed, 20 Mar 2024 18:11:11 +0000
Subject: [PATCH] Add TODO for optimization to avoid sqrt

Signed-off-by: Ryan Friedman <ryan.friedman@avinc.com>
---
 alg/los.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/alg/los.cpp b/alg/los.cpp
index ce3d77cbb9e9..da62f9c72248 100644
--- a/alg/los.cpp
+++ b/alg/los.cpp
@@ -221,6 +221,10 @@ bool GDALIsLineOfSightVisible(const GDALRasterBandH hBand, const int xA,
     {
         const auto rNum = SQUARE(x - xA) + SQUARE(y - yA);
         const auto rDenom = SQUARE(xB - xA) + SQUARE(yB - yA);
+        /// @todo In order to reduce CPU cost and avoid a sqrt operation, consider
+        /// the approach to just the ratio along x or y depending on whether
+        /// the line is steep or shallow.
+        /// See https://github.com/OSGeo/gdal/pull/9506#discussion_r1532459689.
         const double ratio =
             sqrt(static_cast<double>(rNum) / static_cast<double>(rDenom));
         return lerp(zA, zB, ratio);