From d34d712fa3113818d5a2e0da261553d5ec624e77 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Wed, 16 Dec 2020 11:03:30 +0300
Subject: [PATCH] 2D physics example (wip)

---
 examples/physics_2d.cpp | 53 +++++++++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 10 deletions(-)

diff --git a/examples/physics_2d.cpp b/examples/physics_2d.cpp
index 0cce76cd..ab4216f5 100644
--- a/examples/physics_2d.cpp
+++ b/examples/physics_2d.cpp
@@ -41,7 +41,7 @@ struct physics_2d_app
 	float physics_lag = 0.f;
 
 	phys2d::engine::material_handle material;
-	phys2d::engine::shape_handle ball_shape, large_ball_shape, box_shape, small_box_shape;
+	phys2d::engine::shape_handle ball_shape, large_ball_shape, box_shape, small_box_shape, wide_box_shape;
 	phys2d::engine::group_handle ball_group, box_group;
 
 	float const world_width = 5.f;
@@ -49,7 +49,7 @@ struct physics_2d_app
 
 	float const line_width = 0.05f;
 
-	float const ball_radius = 0.5f;
+	float const ball_radius = 0.25f;
 	float const box_width = 0.5f;
 	float const box_height = 0.25f;
 
@@ -80,7 +80,7 @@ struct physics_2d_app
 
 		float const inf = std::numeric_limits<float>::infinity();
 
-		material = physics.add_material({1.f, 0.5f, 1.f});
+		material = physics.add_material({1.f, 0.5f, 0.5f});
 
 		ball_shape = physics.add_shape(phys2d::ball{ball_radius});
 		ball_group = physics.create_group();
@@ -92,6 +92,8 @@ struct physics_2d_app
 
 		small_box_shape = physics.add_shape(phys2d::box{box_width / 2.f, box_height});
 
+		wide_box_shape = physics.add_shape(phys2d::box{box_width * 8.f, box_height});
+
 		int nx = std::ceil(simulation_box[0].length() / box_width);
 		int ny = std::ceil(simulation_box[1].length() / box_height);
 
@@ -114,7 +116,7 @@ struct physics_2d_app
 //		if (false)
 		{
 			int chess = 1;
-			for (int y = 0; y < 5; ++y)
+			for (int y = 0; y < 4; ++y)
 			{
 				if (chess && (y % 2))
 				{
@@ -154,7 +156,7 @@ struct physics_2d_app
 		}
 
 		auto wall_group = physics.create_group();
-		auto wall_material = physics.add_material({inf, 0.5f, 1.f});
+		auto wall_material = physics.add_material({inf, 0.5f, 1.5f});
 
 		auto wall_0_shape = physics.add_shape(phys2d::half_space{{1.f, 0.f}, simulation_box[0].min});
 		physics.add_object(wall_group, wall_0_shape, wall_material, {}, {});
@@ -191,6 +193,15 @@ struct physics_2d_app
 		loop.dispatch_at(std::chrono::system_clock::now() + std::chrono::seconds{1}, [this]{
 			physics.explode(simulation_box.corner(0.5f, -0.2f), 1000.f, 100.f);
 		});
+
+//		loop.dispatch_at(std::chrono::system_clock::now() + std::chrono::seconds{5}, [this]{
+//			stop();
+//		});
+	}
+
+	~physics_2d_app()
+	{
+		util::profiler::dump();
 	}
 
 	void on_resize(int width, int height) override
@@ -218,9 +229,10 @@ struct physics_2d_app
 		}
 		else if (mouse)
 		{
-			physics.add_object(ball_group, ball_shape, material, {*mouse, 0.f}, {{0.f, 0.f}, 0.f});
-//			physics.add_object(box_group, box_shape, material, {*mouse, 0.f}, {});
+//			physics.add_object(ball_group, ball_shape, material, {*mouse, 0.f}, {{0.f, 0.f}, 0.f});
 //			physics.add_object(ball_group, large_ball_shape, material, {*mouse, 0.f}, {});
+			physics.add_object(box_group, box_shape, material, {*mouse, 0.f}, {});
+//			physics.add_object(box_group, wide_box_shape, material, {*mouse, 0.f}, {});
 		}
 	}
 
@@ -237,7 +249,10 @@ struct physics_2d_app
 
 		if (mouse)
 		{
-			physics.explode(*mouse, 1000.f, 100.f);
+			physics.add_object(ball_group, ball_shape, material, {*mouse, 0.f}, {{0.f, 0.f}, 0.f});
+//			physics.add_object(box_group, box_shape, material, {*mouse, 0.f}, {});
+//			physics.add_object(box_group, wide_box_shape, material, {*mouse, 0.f}, {});
+//			physics.explode(*mouse, 10.f, 100.f);
 		}
 	}
 
@@ -253,6 +268,8 @@ struct physics_2d_app
 
 	void update() override
 	{
+		util::profiler prof("update");
+
 		float MOTOR = 15.f;
 
 		float m = 0.f;
@@ -362,16 +379,32 @@ struct physics_2d_app
 		float const frame_dt = frame_clock.restart().count();
 		physics_lag += frame_dt;
 
-		float const physics_dt = 0.002f;
+		static int frame_count = 0;
+
+		float const physics_dt = 0.001f;
+		float const max_physics_time = 0.01f;
+		if (false)
 		while (physics_lag > physics_dt)
-//		if (physics_lag > physics_dt)
 		{
 			physics_lag -= physics_dt;
 			physics.update(physics_dt);
 			for (int i = 0; i < 8; ++i)
 				apply_constraints(physics_dt, 1.f);
+
+			if (false && frame_clock.count() > max_physics_time)
+			{
+				log::warning() << "Can't keep up with physics, running " << physics_lag << "s behind";
+				break;
+			}
 		}
 
+		for (int i = 0; i < 16; ++i)
+			physics.update(physics_dt);
+
+		++frame_count;
+		if (frame_count == 300)
+			stop();
+
 		if (!drag_delta)
 		{
 			selected_ball = std::nullopt;