From 1d797346f7b3e31b43baabdf37650658fe2f7142 Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Thu, 8 Jan 2026 15:12:34 +0100
Subject: Dangling things

---
 examples/particles_gpu/particles_gpu.cpp | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

(limited to 'examples/particles_gpu/particles_gpu.cpp')

diff --git a/examples/particles_gpu/particles_gpu.cpp b/examples/particles_gpu/particles_gpu.cpp
index 2f2d691..2fa44c1 100644
--- a/examples/particles_gpu/particles_gpu.cpp
+++ b/examples/particles_gpu/particles_gpu.cpp
@@ -31,25 +31,32 @@ saw::error_or<void> lbm_main(int argc, char** argv){
 			auto& old_pos = body.template get<"position_old">();
 			auto& acceleration = body.template get<"acceleration">();
 			auto& p_size = part.template get<"size">();
-			p_size = {0.5f};
+			auto& p_rad = part.template get<"collision">().template get<"radius">();
+			p_size = {0.4f};
+			p_rad = {0.4f};
 
-			if(j.get() % 2u == 0) acceleration.at({{1u}}) = {9.81};
+			if(j.get() % 2u == 0) acceleration.at({{1u}}) = {-9.81};
 
-			pos.at({{0u}}) = {i.template cast_to<sch::Float32>()};
-			pos.at({{1u}}) = {j.template cast_to<sch::Float32>()};
+			pos.at({{0u}}) = {i.template cast_to<sch::Float32>()+0.5f};
+			pos.at({{1u}}) = {j.template cast_to<sch::Float32>()+64.0f};
 
 			old_pos = pos;
 		}
 	}
 
 	for(saw::data<sch::UInt64> dt{0u}; dt < saw::data<sch::UInt64>{32ul}; ++dt){
+		// Do Verlet Step
 		for(saw::data<sch::UInt64> i{0u}; i < particles.size(); ++i){
 			auto& part_i = particles.at(i);
 
 			verlet_step_lambda<sch::Float32,2u>(part_i,{0.05f});
 		}
+		//
 		for(saw::data<sch::UInt64> i{0u}; i < particles.size(); ++i){
 			auto& part_i = particles.at(i);
+			/**
+			 * Test against other particles
+			 */
 			for(saw::data<sch::UInt64> j{i+1ul}; j < particles.size(); ++j){
 				auto& part_j = particles.at(j);
 
@@ -58,9 +65,24 @@ saw::error_or<void> lbm_main(int argc, char** argv){
 					std::cout<<"Collision"<<std::endl;
 				}
 			}
+			/**
+			 * Test against walls
+			 */
+			auto& body_i = part_i.template get<"rigid_body">();
+			auto& pos_i = body_i.template get<"position">();
+			auto& pos_old_i = body_i.template get<"position_old">();
+			if(pos_i.at({{0u}}).get() <= 0 or pos_i.at({{0u}}).get() >= 40 ){
+				auto pos_i_0 = pos_i.at({{0u}});
+				pos_i.at({{0u}}) = pos_old_i.at({{0u}});
+				pos_old_i.at({{0u}}) = pos_i_0;
+			}
+			if(pos_i.at({{1u}}).get() <= 0 or pos_i.at({{1u}}).get() >= 40 ){
+				auto pos_i_1 = pos_i.at({{1u}});
+				pos_i.at({{1u}}) = pos_old_i.at({{1u}});
+				pos_old_i.at({{1u}}) = pos_i_1;
+			}
 		}
 		auto& pos = particles.at({0u}).template get<"rigid_body">().template get<"position">();
-		std::cout<<pos.at({{0u}}).get()<<" "<<pos.at({{1u}}).get()<<std::endl;
 
 		saw::codec<sch::Array<sch::Particle<sch::Float32,2u>>, saw::encode::Json> j_codec;
 	}
-- 
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