From 1693f8ccb3fbdbc8a1bd35a5ffde684ca4c68a3f Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Sat, 18 Jul 2026 21:45:14 +0200
Subject: Dangling

---
 modules/core/c++/particle/particle.hpp | 39 +++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

(limited to 'modules/core/c++/particle/particle.hpp')

diff --git a/modules/core/c++/particle/particle.hpp b/modules/core/c++/particle/particle.hpp
index 3c3630a..6d57930 100644
--- a/modules/core/c++/particle/particle.hpp
+++ b/modules/core/c++/particle/particle.hpp
@@ -137,7 +137,44 @@ saw::data<sch::Particle<T,D, sch::ParticleCollisionSpheroid<T>>> create_spheroid
 */
 
 template<typename T,uint64_t D>
-constexpr auto verlet_step_lambda = [](saw::data<sch::Particle<T,D>>& particle, saw::data<sch::Scalar<T>> time_step_delta){
+constexpr auto verlet_step_lambda_old = [](saw::data<sch::Particle<T,D>>& particle, saw::data<sch::Scalar<T>> time_step_delta){
+	auto& body = particle.template get<"rigid_body">();
+
+	auto& pos = body.template get<"position">();
+	auto& pos_old = body.template get<"position_old">();
+
+	auto& pos_acc = body.template get<"acceleration">();
+	
+	auto& rot = body.template get<"rotation">();
+	auto& rot_old = body.template get<"rotation_old">();
+
+	auto& rot_acc = body.template get<"angular_acceleration">();
+
+	auto tsd_squared = time_step_delta * time_step_delta;
+
+	saw::data<sch::Vector<T,D>> pos_new;
+	// Actual step
+	saw::data<sch::Scalar<T>> two;
+	two.at({}).set(2.0);
+	pos_new = pos * two - pos_old + pos_acc * tsd_squared;
+
+	// Angular
+	saw::data<typename sch::impl::rotation_type_helper<T,D>::Schema> rot_new;
+	rot_new = rot * two - rot_old + rot_acc * tsd_squared;
+
+	// Swap - Could be std::swap?
+	pos_old = pos;
+	pos = pos_new;
+
+	rot_old = rot;
+	rot = rot_new;
+};
+
+template<typename T,uint64_t D,uint64_t PC, typename Coll>
+constexpr auto verlet_step_lambda = [](saw::data<sch::ParticleGroup<T,D,PC,Coll>>& pgrp, saw::data<sch::FixedArray<T,1u>> index, saw::data<sch::Scalar<T>> time_step_delta){
+	auto& parts = pgrp.template get<"particles">();
+	auto& particle = parts.at(index);
+
 	auto& body = particle.template get<"rigid_body">();
 
 	auto& pos = body.template get<"position">();
-- 
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