[wpimath] Add 3D geometry classes (#4175)

Also clean up 2D geometry documentation.

wpimath/src/main/native/cpp/geometry/Transform3d.cpp

@@ -0,0 +1,41 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "frc/geometry/Transform3d.h"
+
+#include "frc/geometry/Pose3d.h"
+
+using namespace frc;
+
+Transform3d::Transform3d(Pose3d initial, Pose3d final) {
+  // We are rotating the difference between the translations
+  // using a clockwise rotation matrix. This transforms the global
+  // delta into a local delta (relative to the initial pose).
+  m_translation = (final.Translation() - initial.Translation())
+                      .RotateBy(-initial.Rotation());
+
+  m_rotation = final.Rotation() - initial.Rotation();
+}
+
+Transform3d::Transform3d(Translation3d translation, Rotation3d rotation)
+    : m_translation(std::move(translation)), m_rotation(std::move(rotation)) {}
+
+Transform3d Transform3d::Inverse() const {
+  // We are rotating the difference between the translations
+  // using a clockwise rotation matrix. This transforms the global
+  // delta into a local delta (relative to the initial pose).
+  return Transform3d{(-Translation()).RotateBy(-Rotation()), -Rotation()};
+}
+
+Transform3d Transform3d::operator+(const Transform3d& other) const {
+  return Transform3d{Pose3d{}, Pose3d{}.TransformBy(*this).TransformBy(other)};
+}
+
+bool Transform3d::operator==(const Transform3d& other) const {
+  return m_translation == other.m_translation && m_rotation == other.m_rotation;
+}
+
+bool Transform3d::operator!=(const Transform3d& other) const {
+  return !operator==(other);
+}