From ac29687ff4409317eff4230f05c8d0aa89a285b6 Mon Sep 17 00:00:00 2001
From: Patrizia Kaye <github@ethernull.org>
Date: Sat, 16 Nov 2024 00:18:34 +0100
Subject: [PATCH 1/2] Fix autoscaling of structures.

In rescaleToUnit, the transformation is computed as a vector with three components, each 1/lengthScale.
However, when computing the determinant of this, it results in a scaling of 1/lengthScale^3.
Therefore compute the inverse scale as 1/std::cbrt(lengthScale).
---
 src/structure.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/structure.cpp b/src/structure.cpp
index ba1aa1c0..428602bc 100644
--- a/src/structure.cpp
+++ b/src/structure.cpp
@@ -215,7 +215,7 @@ void Structure::centerBoundingBox() {
 
 void Structure::rescaleToUnit() {
   double currScale = lengthScale();
-  float s = static_cast<float>(1.0 / currScale);
+  float s = static_cast<float>(1.0 / std::cbrt(currScale));
   glm::mat4x4 newTrans = glm::scale(glm::mat4x4(1.0), glm::vec3{s, s, s});
   objectTransform = newTrans * objectTransform.get();
   updateStructureExtents();

From 35e056da4659a9e53f677d84ff063c50ac58b49b Mon Sep 17 00:00:00 2001
From: Nicholas Sharp <nmwsharp@gmail.com>
Date: Sat, 28 Dec 2024 14:51:46 -0500
Subject: [PATCH 2/2] move cbrt to length scale computation

---
 src/structure.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/structure.cpp b/src/structure.cpp
index 428602bc..99fb4166 100644
--- a/src/structure.cpp
+++ b/src/structure.cpp
@@ -21,7 +21,7 @@ Structure::Structure(std::string name_, std::string subtypeName)
   validateName(name);
 }
 
-Structure::~Structure(){};
+Structure::~Structure() {};
 
 Structure* Structure::setEnabled(bool newEnabled) {
   if (newEnabled == isEnabled()) return this;
@@ -173,7 +173,7 @@ std::tuple<glm::vec3, glm::vec3> Structure::boundingBox() {
 float Structure::lengthScale() {
   // compute the scaling caused by the object transform
   const glm::mat4x4& T = objectTransform.get();
-  float transScale = std::abs(glm::determinant(glm::mat3x3(T))) / T[3][3];
+  float transScale = std::cbrt(std::abs(glm::determinant(glm::mat3x3(T)))) / T[3][3];
   return transScale * objectSpaceLengthScale;
 }
 
@@ -215,7 +215,7 @@ void Structure::centerBoundingBox() {
 
 void Structure::rescaleToUnit() {
   double currScale = lengthScale();
-  float s = static_cast<float>(1.0 / std::cbrt(currScale));
+  float s = static_cast<float>(1.0 / currScale);
   glm::mat4x4 newTrans = glm::scale(glm::mat4x4(1.0), glm::vec3{s, s, s});
   objectTransform = newTrans * objectTransform.get();
   updateStructureExtents();