From 950d8f20f981c00ad484d2596a95bffb63966205 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 19 May 2023 23:38:10 +0300
Subject: [PATCH] Support adding prop entities to Landscape

---
 source/game/landscape.cpp | 26 +++++++++++++++++++++-----
 source/game/landscape.h   | 28 +++++++++++++++++++++++++++-
 2 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/source/game/landscape.cpp b/source/game/landscape.cpp
index 1612d44..c9c2814 100644
--- a/source/game/landscape.cpp
+++ b/source/game/landscape.cpp
@@ -1,7 +1,6 @@
 #include "landscape.h"
 #include "entity.h"
 #include "root.h"
-#include "transform.h"
 
 using namespace std;
 
@@ -18,6 +17,11 @@ Landscape::Landscape(Stage &s, const HeightmapTerrainSetup &t, float b):
 	block_size = grid_size*terrain_setup.grid_spacing;
 }
 
+bool Landscape::terrain_index_compare(const Terrain &t, const LinAl::Vector<int, 2> &i)
+{
+	return t.index.y<i.y || (t.index.y==i.y && t.index.x<i.x);
+}
+
 void Landscape::set_generator(LandscapeGenerator *g)
 {
 	generator = g;
@@ -33,9 +37,7 @@ void Landscape::generate(const Geometry::BoundingBox<float, 2> &bounds)
 
 	for(int y=min_index.y; y<=max_index.y; ++y)
 	{
-		auto i = lower_bound(terrains, LinAl::Vector<int, 2>(min_index.x, y), [](const Terrain &t, const LinAl::Vector<int, 2> &n){
-			return t.index.y<n.y || (t.index.y==n.y && t.index.x<n.x);
-		});
+		auto i = lower_bound(terrains, LinAl::Vector<int, 2>(min_index.x, y), terrain_index_compare);
 
 		for(int x=min_index.x; x<=max_index.x; ++x)
 		{
@@ -48,7 +50,7 @@ void Landscape::generate(const Geometry::BoundingBox<float, 2> &bounds)
 				if(generator)
 				{
 					LinAl::Vector<float, 2> base = center-block_size_vec/2.0f;
-					generator->generate_block({ base, base+block_size_vec }, terrain);
+					generator->generate_block(*this, { base, base+block_size_vec }, terrain);
 				}
 				i = terrains.emplace(i, index, move(entity), move(terrain));
 			}
@@ -57,4 +59,18 @@ void Landscape::generate(const Geometry::BoundingBox<float, 2> &bounds)
 	}
 }
 
+LinAl::Vector<float, 3> Landscape::get_ground_position(const LinAl::Vector<float, 3> &p) const
+{
+	LinAl::Vector<int, 2> index(round(p.x/block_size), round(p.y/block_size));
+	auto i = lower_bound(terrains, index, terrain_index_compare);
+	if(i==terrains.end() || i->index!=index)
+		return compose(p.slice<2>(0), 0.0f);
+
+	LinAl::Vector<float, 3> center = i->entity->get_transform()->get_position();
+	LinAl::Vector<float, 2> corner = center.slice<2>(0) - i->terrain->get_size()/2.0f;
+	LinAl::Vector<float, 2> p_xy = p.slice<2>(0);
+	float z = i->terrain->get_elevation(p_xy-corner);
+	return center+compose(p_xy, z);
+}
+
 } // namespace Msp::Game
diff --git a/source/game/landscape.h b/source/game/landscape.h
index b31402b..9319718 100644
--- a/source/game/landscape.h
+++ b/source/game/landscape.h
@@ -7,10 +7,12 @@
 #include "mspgame_api.h"
 #include "owned.h"
 #include "system.h"
+#include "transform.h"
 
 namespace Msp::Game {
 
 class Entity;
+class Landscape;
 
 class MSPGAME_API LandscapeGenerator
 {
@@ -18,7 +20,7 @@ protected:
 	LandscapeGenerator() = default;
 
 public:
-	virtual void generate_block(const Geometry::BoundingBox<float, 2> &, Handle<HeightmapTerrain>) = 0;
+	virtual void generate_block(Landscape &, const Geometry::BoundingBox<float, 2> &, Handle<HeightmapTerrain>) = 0;
 };
 
 class MSPGAME_API Landscape: public System
@@ -31,22 +33,46 @@ private:
 		Owned<HeightmapTerrain> terrain;
 	};
 
+	struct Prop
+	{
+		Owned<Entity> entity;
+	};
+
 	Owned<Entity> subroot;
 	const HeightmapTerrainSetup &terrain_setup;
 	float block_size = 100.0f;
 	LandscapeGenerator *generator = nullptr;
 	std::vector<Terrain> terrains;
+	std::vector<Prop> props;
 
 public:
 	Landscape(Stage &, const HeightmapTerrainSetup &, float);
 
+private:
+	static bool terrain_index_compare(const Terrain &, const LinAl::Vector<int, 2> &);
+
+public:
 	void set_generator(LandscapeGenerator *);
 	void generate(const Geometry::BoundingBox<float, 2> &);
 	LinAl::Vector<float, 3> get_ground_position(const LinAl::Vector<float, 3> &) const;
 
+	template<typename T>
+		requires std::is_base_of_v<Entity, T>
+	void add_prop(const T::Setup &, TransformValues);
+
 	void tick(Time::TimeDelta) override { }
 };
 
+
+template<typename T>
+	requires std::is_base_of_v<Entity, T>
+void Landscape::add_prop(const T::Setup &setup, TransformValues tf)
+{
+	tf.position = get_ground_position(tf.position);
+	Owned<T> prop(subroot, setup, tf);
+	props.emplace_back(std::move(prop));
+}
+
 } // namespace Msp::Game
 
 #endif
-- 
2.45.2