From bc79111c07e799a76b346f2f0451a7b5bb8bda56 Mon Sep 17 00:00:00 2001
From: Pascal Serrarens <pse@pale.blue>
Date: Tue, 1 Jul 2025 18:01:18 +0200
Subject: [PATCH] Added partial impl. triangulation

---
 LinearAlgebra/Matrix.cpp     | 34 +++++++++++++++++++++++++++++++++-
 LinearAlgebra/Matrix.h       |  7 ++++++-
 LinearAlgebra/Quaternion.cpp |  4 ++++
 LinearAlgebra/Quaternion.h   |  2 ++
 4 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/LinearAlgebra/Matrix.cpp b/LinearAlgebra/Matrix.cpp
index edde63e..73b18c8 100644
--- a/LinearAlgebra/Matrix.cpp
+++ b/LinearAlgebra/Matrix.cpp
@@ -22,6 +22,10 @@ Matrix1::Matrix1(float* data, int size) : data(data), size(size) {
   this->externalData = true;
 }
 
+Vector3 Matrix1::ToVector3() {
+  return Vector3(this->data[0], this->data[1], this->data[2]);
+}
+
 Matrix1 LinearAlgebra::Matrix1::FromQuaternion(Quaternion q) {
   Matrix1 r = Matrix1(4);
   float* data = r.data;
@@ -37,7 +41,15 @@ Quaternion LinearAlgebra::Matrix1::ToQuaternion() {
 }
 
 Matrix1 Matrix1::Slice(int start, int stop) {
-  return Matrix1();
+  if (start < 0 || stop >= this->size)
+    std::cerr << "Slice index out of range." << std::endl;
+
+  Matrix1 result(stop - start);
+  int resultIx = 0;
+  for (int ix = start; ix < stop; ix++)
+    result.data[resultIx++] = this->data[ix];
+
+  return result;
 }
 
 // Matrix1
@@ -251,6 +263,26 @@ Matrix2 Matrix2::GetRows(int from, int to) {
   return result;
 }
 
+Vector3 Matrix2::GetRow3(int rowIx) {
+  int cellIx = rowIx * this->nCols;
+  Vector3 row(this->data[cellIx, 0], this->data[cellIx, 1],
+              this->data[cellIx, 2]);
+  return row;
+}
+
+void Matrix2::SetRow(int rowIx, Matrix1 source) {
+  int cellIx = rowIx * this->nCols;
+  for (int ix = 0; ix < source.size; ix++)
+    this->data[cellIx + ix] = source.data[ix];
+}
+
+void Matrix2::SetRow3(int rowIx, Vector3 v) {
+  int cellIx = rowIx * this->nCols;
+  this->data[cellIx + 0] = v.x;
+  this->data[cellIx + 1] = v.y;
+  this->data[cellIx + 2] = v.z;
+}
+
 Matrix2 Matrix2::Slice(int rowStart, int rowStop, int colStart, int colStop) {
   Matrix2 r = Matrix2(rowStop - rowStart, colStop - colStart);
 
diff --git a/LinearAlgebra/Matrix.h b/LinearAlgebra/Matrix.h
index 5c7bcdc..be94054 100644
--- a/LinearAlgebra/Matrix.h
+++ b/LinearAlgebra/Matrix.h
@@ -16,6 +16,8 @@ class Matrix1 {
   Matrix1(int size);
   Matrix1(float* data, int size);
 
+  Vector3 ToVector3();
+
   static Matrix1 FromQuaternion(Quaternion q);
   Quaternion ToQuaternion();
 
@@ -120,8 +122,11 @@ class Matrix2 {
   }
 
   Matrix2 GetRows(int from, int to);
+  Vector3 GetRow3(int rowIx);
+
+  void SetRow(int rowIx, Matrix1 source);
+  void SetRow3(int rowIx, Vector3 v);
 
-  void SetRow(int rowIx, Matrix1 source) {}
   Matrix2 Slice(int rawStart, int rowStop, int colStart, int colStop);
 
   void UpdateSlice(int rowStart,
diff --git a/LinearAlgebra/Quaternion.cpp b/LinearAlgebra/Quaternion.cpp
index dda8c18..5bb5ecd 100644
--- a/LinearAlgebra/Quaternion.cpp
+++ b/LinearAlgebra/Quaternion.cpp
@@ -168,6 +168,10 @@ Quaternion Quaternion::Inverse(Quaternion r) {
   return Quaternion(-r.x / n, -r.y / n, -r.z / n, r.w / n);
 }
 
+Quaternion Quaternion::Reflect(Quaternion q) {
+  return Quaternion(-q.x, -q.y, -q.z, q.w);
+}
+
 Quaternion Quaternion::LookRotation(const Vector3& forward) {
   Vector3 up = Vector3(0, 1, 0);
   return LookRotation(forward, up);
diff --git a/LinearAlgebra/Quaternion.h b/LinearAlgebra/Quaternion.h
index 1687dc9..9c12c2c 100644
--- a/LinearAlgebra/Quaternion.h
+++ b/LinearAlgebra/Quaternion.h
@@ -126,6 +126,8 @@ struct Quaternion : Quat {
   /// needed</param> <returns>The inverted quaternion</returns>
   static Quaternion Inverse(Quaternion quaternion);
 
+  static Quaternion Reflect(Quaternion q);
+
   /// <summary>
   /// A rotation which looks in the given direction
   /// </summary>