diff --git a/assets/basic.png b/assets/basic.png
new file mode 100644
index 0000000..1548bce
Binary files /dev/null and b/assets/basic.png differ
diff --git a/2d.hpp b/include/2d.h
similarity index 80%
rename from 2d.hpp
rename to include/2d.h
index 71eeba5..9f7681c 100644
--- a/2d.hpp
+++ b/include/2d.h
@@ -5,19 +5,25 @@
 #include <complex>
 #include <initializer_list>
 
+namespace arras {
+
 using Float = float;
 using Vec2 = std::complex<Float>;
 
 const Float eps = 1e-6;
 
-Float cross(const Vec2& a, const Vec2& b) {
+inline Float cross(const Vec2& a, const Vec2& b) {
 	return a.real() * b.imag() - a.imag() * b.real();
 }
 
-Float dot(const Vec2& a, const Vec2& b) {
+inline Float dot(const Vec2& a, const Vec2& b) {
 	return a.real() * b.real() + a.imag() * b.imag();
 }
 
+inline Float asAngle(const Vec2& d) {
+	return std::atan2(d.imag(), d.real());
+}
+
 struct Circle {
 	Vec2 o;
 	Float r;
@@ -39,8 +45,10 @@ struct Polygon {
 	Polygon(const std::array<Vec2, n>& v): vertex(v) {}
 	Polygon(std::initializer_list<Vec2>&& v) {
 		int i = 0;
-		for (auto &&x : v) {
-			if (i >= n) break;
+		for (auto&& x : v) {
+			if (i >= n) {
+				break;
+			}
 			vertex[i] = x;
 			i += 1;
 		}
@@ -64,12 +72,12 @@ struct Polygon {
 	}
 };
 
-bool intersect(const Circle& a, const Circle& b) {
+inline bool intersect(const Circle& a, const Circle& b) {
 	return abs(a.o - b.o) <= a.r + b.r;
 }
 
 template<int n, int m>
-bool intersect(const Polygon<n>& a, const Polygon<m>& b) {
+inline bool intersect(const Polygon<n>& a, const Polygon<m>& b) {
 	for (int i = 0; i < n; i++) {
 		if (b.contain(a[i])) {
 			return true;
@@ -98,7 +106,7 @@ bool intersect(const Polygon<n>& a, const Polygon<m>& b) {
 }
 
 template<int n>
-bool intersect(const Polygon<n>& a, const Circle& b) {
+inline bool intersect(const Polygon<n>& a, const Circle& b) {
 	if (a.contain(b.o)) {
 		return true;
 	}
@@ -121,8 +129,9 @@ bool intersect(const Polygon<n>& a, const Circle& b) {
 }
 
 template<int n>
-bool intersect(const Circle& b, const Polygon<n>& a) {
+inline bool intersect(const Circle& b, const Polygon<n>& a) {
 	return intersect(a, b);
 }
+}
 
 #endif
diff --git a/include/render.h b/include/render.h
new file mode 100644
index 0000000..1e009cd
--- /dev/null
+++ b/include/render.h
@@ -0,0 +1,98 @@
+#ifndef HEADER_ARRAS_RENDER_H
+#define HEADER_ARRAS_RENDER_H
+
+extern "C" {
+#include <SDL2/SDL.h>
+#include <SDL2/SDL_image.h>
+}
+
+#include "2d.h"
+#include <fmt/core.h>
+#include <memory>
+#include <stdexcept>
+#include <utility>
+
+namespace arras {
+
+struct Color {
+	uint8_t r, g, b, a;
+
+	Color();
+	Color(uint8_t r, uint8_t g, uint8_t b, uint8_t a);
+};
+
+std::shared_ptr<SDL_Rect> makeRect(int x, int y, int w, int h);
+std::shared_ptr<SDL_FRect> makeFRect(const arras::Vec2& pos, const arras::Vec2& size);
+
+class RenderSurface {
+public:
+	RenderSurface(RenderSurface&& rs);
+	RenderSurface(const RenderSurface& rs);
+	explicit RenderSurface(SDL_RWops* src);
+	RenderSurface(int width, int height);
+
+	~RenderSurface();
+
+	SDL_Surface* nativeHandle() const noexcept;
+
+	int width() const noexcept;
+	int height() const noexcept;
+
+private:
+	SDL_Surface* s;
+};
+
+class RenderWindow;
+
+class RenderTexture {
+	RenderTexture(const RenderTexture&) = delete;
+	RenderTexture& operator=(const RenderTexture&) = delete;
+
+public:
+	RenderTexture(RenderTexture&& rt);
+	RenderTexture(const RenderWindow& rd, SDL_RWops* src);
+	RenderTexture(const RenderWindow& rd, const RenderSurface& rs);
+
+	~RenderTexture();
+
+	SDL_Texture* nativeHandle() const noexcept;
+
+	int width() const noexcept;
+	int height() const noexcept;
+
+	std::pair<int, int> calcRenderSize(int w, int h) const noexcept;
+
+private:
+	SDL_Texture* t;
+	int w, h;
+};
+
+class RenderWindow {
+	RenderWindow(const RenderWindow&) = delete;
+	RenderWindow& operator=(const RenderWindow&) = delete;
+
+public:
+	RenderWindow(RenderWindow&& rd);
+	RenderWindow(int w, int h);
+
+	~RenderWindow();
+
+	SDL_Renderer* nativeHandle() const noexcept;
+
+	void renderTextureAt(const RenderTexture& t, const Vec2& pos) const;
+	void renderTextureAt(const RenderTexture& t, const Vec2& pos, const Vec2& direction) const;
+
+	void present() const noexcept;
+	void clear(const Color& c = {}) const;
+
+	int width() const noexcept;
+	int height() const noexcept;
+
+private:
+	int w, h;
+	SDL_Window* window;
+	SDL_Renderer* renderer;
+};
+}  // namespace arras
+
+#endif
diff --git a/main.cpp b/main.cpp
new file mode 100644
index 0000000..d643d1f
--- /dev/null
+++ b/main.cpp
@@ -0,0 +1,32 @@
+#include "2d.h"
+#include "render.h"
+#include <chrono>
+#include <thread>
+#include <cmath>
+
+int main() {
+	arras::RenderWindow w(2360, 1240);
+	arras::RenderTexture t(w, SDL_RWFromFile("assets/basic.png", "rb"));
+	std::printf("%d %d\n", t.width(), t.height());
+
+	const float PI = acos(-1);
+	arras::Vec2 d{1, 0}, v{std::cos(PI / 300), std::sin(PI / 300)};
+	SDL_Event evt;
+	while (true) {
+		while (SDL_PollEvent(&evt)) {
+			if (evt.type == SDL_QUIT) {
+				break;
+			}
+		}
+
+		w.clear();
+		w.renderTextureAt(t, {200, 200}, d);
+		w.present();
+		d *= v;
+		// pos += v;
+		// if (pos.real() > 1000 || pos.real() < 200) {
+		// 	v *= -1;
+		// }
+		std::this_thread::sleep_for(std::chrono::milliseconds(16));
+	}
+}
diff --git a/objects.hpp b/objects.hpp
new file mode 100644
index 0000000..342cd51
--- /dev/null
+++ b/objects.hpp
@@ -0,0 +1,32 @@
+#ifndef HEADER_OBJECTS_HPP
+#define HEADER_OBJECTS_HPP
+
+#include "2d.h"
+#include <entt/entt.hpp>
+
+namespace arras {
+
+struct Transform {
+	Vec2 position;
+};
+
+struct Velocity {
+	Vec2 velocity;
+};
+
+struct EngineAcceleration {
+	Vec2 ideal_velocity;
+	Float acceleration;
+};
+
+inline entt::entity makeTank(entt::registry &r, Vec2 position) {
+	const auto e = r.create();
+	r.emplace<Transform>(e, Transform{position});
+	r.emplace<Velocity>(e, Velocity{{0, 0}});
+	r.emplace<EngineAcceleration>(e, EngineAcceleration{{0, 0}, 1});
+	return e;
+}
+
+}
+
+#endif
\ No newline at end of file
diff --git a/src/render/misc.cpp b/src/render/misc.cpp
new file mode 100644
index 0000000..5ca083b
--- /dev/null
+++ b/src/render/misc.cpp
@@ -0,0 +1,42 @@
+#include "render.h"
+
+namespace {
+
+class SDLLoader {
+private:
+	SDLLoader() {
+		SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS);
+		SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "best");
+		IMG_Init(IMG_INIT_PNG);
+	}
+
+	~SDLLoader() {
+		IMG_Quit();
+		SDL_Quit();
+	}
+
+	static const SDLLoader _;
+};
+
+}  // namespace
+
+arras::Color::Color(): r(255), g(255), b(255), a(255) {}
+arras::Color::Color(uint8_t r, uint8_t g, uint8_t b, uint8_t a): r(r), g(g), b(b), a(a) {}
+
+std::shared_ptr<SDL_Rect> arras::makeRect(int x, int y, int w, int h) {
+	auto res = std::make_shared<SDL_Rect>();
+	res->x = x;
+	res->y = y;
+	res->w = w;
+	res->h = h;
+	return res;
+}
+
+std::shared_ptr<SDL_FRect> arras::makeFRect(const arras::Vec2& pos, const arras::Vec2& size) {
+	auto res = std::make_shared<SDL_FRect>();
+	res->x = pos.real();
+	res->y = pos.imag();
+	res->w = size.real();
+	res->h = size.imag();
+	return res;
+}
diff --git a/src/render/surface.cpp b/src/render/surface.cpp
new file mode 100644
index 0000000..70146ad
--- /dev/null
+++ b/src/render/surface.cpp
@@ -0,0 +1,53 @@
+#include "render.h"
+
+using namespace arras;
+
+RenderSurface::RenderSurface(RenderSurface&& rs): s(rs.s) {
+	rs.s = nullptr;
+}
+
+RenderSurface::RenderSurface(const RenderSurface& rs) {
+	s = SDL_CreateRGBSurfaceWithFormat(0, rs.width(), rs.height(), 32, SDL_PIXELFORMAT_RGBA8888);
+	if (!s) {
+		throw std::runtime_error(
+			fmt::format("SDL_CreateRGBSurfaceWithFormat() failed: {}", SDL_GetError()));
+	}
+	if (SDL_BlitSurface(rs.nativeHandle(),
+						nullptr,
+						s,
+						makeRect(0, 0, rs.width(), rs.height()).get())
+		!= 0) {
+		throw std::runtime_error(fmt::format("SDL_BlitSurface() failed: {}", SDL_GetError()));
+	}
+}
+
+RenderSurface::RenderSurface(SDL_RWops* src) {
+	s = IMG_Load_RW(src, 1);
+	if (!s) {
+		throw std::runtime_error(fmt::format("IMG_Load_RW() failed: {}", IMG_GetError()));
+	}
+}
+
+RenderSurface::RenderSurface(int width, int height) {
+	s = SDL_CreateRGBSurfaceWithFormat(0, width, height, 32, SDL_PIXELFORMAT_RGBA8888);
+	if (!s) {
+		throw std::runtime_error(
+			fmt::format("SDL_CreateRGBSurfaceWithFormat() failed: {}", SDL_GetError()));
+	}
+}
+
+RenderSurface ::~RenderSurface() {
+	SDL_FreeSurface(s);
+}
+
+SDL_Surface* RenderSurface::nativeHandle() const noexcept {
+	return s;
+}
+
+int RenderSurface::width() const noexcept {
+	return s->w;
+}
+
+int RenderSurface::height() const noexcept {
+	return s->h;
+}
\ No newline at end of file
diff --git a/src/render/texture.cpp b/src/render/texture.cpp
new file mode 100644
index 0000000..5b86e16
--- /dev/null
+++ b/src/render/texture.cpp
@@ -0,0 +1,63 @@
+
+#include "render.h"
+
+using namespace arras;
+
+RenderTexture::RenderTexture(RenderTexture&& rt): t(rt.t) {
+	rt.t = nullptr;
+}
+
+RenderTexture::RenderTexture(const RenderWindow& rd, SDL_RWops* src) {
+	t = IMG_LoadTexture_RW(rd.nativeHandle(), src, 1);
+	if (!t) {
+		throw std::runtime_error(fmt::format("IMG_LoadTexture_RW() failed: {}", IMG_GetError()));
+	}
+	if (SDL_QueryTexture(t, nullptr, nullptr, &w, &h) != 0) {
+		throw std::runtime_error(fmt::format("SDL_QueryTexture() failed: {}", SDL_GetError()));
+	}
+}
+
+RenderTexture::RenderTexture(const RenderWindow& rd, const RenderSurface& rs) {
+	t = SDL_CreateTextureFromSurface(rd.nativeHandle(), rs.nativeHandle());
+	if (!t) {
+		throw std::runtime_error(
+			fmt::format("SDL_CreateRGBSurfaceWithFormat() failed: {}", SDL_GetError()));
+	}
+	if (SDL_QueryTexture(t, nullptr, nullptr, &w, &h)) {
+		throw std::runtime_error(fmt::format("SDL_QueryTexture() failed: {}", SDL_GetError()));
+	}
+}
+
+RenderTexture::~RenderTexture() {
+	SDL_DestroyTexture(t);
+}
+
+SDL_Texture* RenderTexture::nativeHandle() const noexcept {
+	return t;
+}
+
+int RenderTexture::width() const noexcept {
+	return w;
+}
+
+int RenderTexture::height() const noexcept {
+	return h;
+}
+
+std::pair<int, int> RenderTexture::calcRenderSize(int w, int h) const noexcept {
+	int rw, rh;
+	if (w == 0 && h == 0) {
+		rw = width();
+		rh = height();
+	} else if (w == 0) {
+		rw = (h * width() / height());
+		rh = h;
+	} else if (h == 0) {
+		rw = w;
+		rh = (w * height() / width());
+	} else {
+		rw = w;
+		rh = h;
+	}
+	return {rw, rh};
+}
diff --git a/src/render/window.cpp b/src/render/window.cpp
new file mode 100644
index 0000000..90b44a3
--- /dev/null
+++ b/src/render/window.cpp
@@ -0,0 +1,76 @@
+#ifndef HEADER_ARRAS_RENDER_WINDOW_HPP
+#define HEADER_ARRAS_RENDER_WINDOW_HPP
+
+#include "render.h"
+#define Pi 3.14159265358979323846
+
+using namespace arras;
+
+RenderWindow::RenderWindow(RenderWindow&& rd)
+	: w(rd.w), h(rd.h), window(rd.window), renderer(rd.renderer) {
+	rd.renderer = nullptr;
+	rd.window = nullptr;
+}
+
+RenderWindow::RenderWindow(int w, int h): w(w), h(h) {
+	if (SDL_CreateWindowAndRenderer(w, h, SDL_WINDOW_SHOWN | SDL_WINDOW_ALLOW_HIGHDPI, &window, &renderer) != 0) {
+		throw std::runtime_error(
+			fmt::format("SDL_CreateWindowAndRenderer() failed: {}", SDL_GetError()));
+	}
+}
+
+RenderWindow::~RenderWindow() {
+	SDL_DestroyRenderer(renderer);
+	SDL_DestroyWindow(window);
+}
+
+SDL_Renderer* RenderWindow::nativeHandle() const noexcept {
+	return renderer;
+}
+
+void RenderWindow::renderTextureAt(const RenderTexture& t, const Vec2& pos) const {
+	if (SDL_RenderCopyF(renderer,
+						t.nativeHandle(),
+						NULL,
+						makeFRect(pos, {t.width(), t.height()}).get())) {
+		throw std::runtime_error(fmt::format("SDL_RenderCopy() failed: {}", SDL_GetError()));
+	}
+}
+
+void RenderWindow::renderTextureAt(const RenderTexture& t,
+								   const Vec2& pos,
+								   const Vec2& direction) const {
+	if (SDL_RenderCopyExF(renderer,
+						  t.nativeHandle(),
+						  NULL,
+						  makeFRect(pos, {t.width(), t.height()}).get(),
+						  -asAngle(direction) * 180 / Pi,
+						  nullptr,
+						  SDL_FLIP_NONE)) {
+		throw std::runtime_error(fmt::format("SDL_RenderCopy() failed: {}", SDL_GetError()));
+	}
+}
+
+void RenderWindow::present() const noexcept {
+	SDL_RenderPresent(renderer);
+}
+
+void RenderWindow::clear(const Color& c) const {
+	if (SDL_SetRenderDrawColor(renderer, c.r, c.g, c.b, c.a)) {
+		throw std::runtime_error(
+			fmt::format("SDL_SetRenderDrawColor() failed: {}", SDL_GetError()));
+	}
+	if (SDL_RenderClear(renderer)) {
+		throw std::runtime_error(fmt::format("SDL_RenderClear() failed: {}", SDL_GetError()));
+	}
+}
+
+int RenderWindow::width() const noexcept {
+	return w;
+}
+
+int RenderWindow::height() const noexcept {
+	return h;
+}
+
+#endif
diff --git a/test/cases/2d.cpp b/test/cases/2d.cpp
index 0be2e94..c8b5ed8 100644
--- a/test/cases/2d.cpp
+++ b/test/cases/2d.cpp
@@ -1,4 +1,4 @@
-#include "2d.hpp"
+#include "2d.h"
 #include "test/u.hpp"
 #include <functional>
 #include <initializer_list>
@@ -6,6 +6,7 @@
 namespace {
 
 AddTestCase _(1, "2d.hpp", [](TestCase& t) {
+	using namespace arras;
 	t.expectEq<Float>([] { return cross({1, 2}, {4, 1}); }, -7);
 	t.expectEq<Float>([] { return cross({.5, 2.5}, {4, 1.5}); }, -9.25);
 
diff --git a/test/cases/objects.cpp b/test/cases/objects.cpp
new file mode 100644
index 0000000..9c8a420
--- /dev/null
+++ b/test/cases/objects.cpp
@@ -0,0 +1,10 @@
+#include "objects.hpp"
+#include "test/u.hpp"
+
+namespace {
+
+AddTestCase _(1, "objects.hpp", [](TestCase& t) {
+
+});
+
+}
diff --git a/xmake.lua b/xmake.lua
index b23e643..d5d6fe6 100644
--- a/xmake.lua
+++ b/xmake.lua
@@ -4,13 +4,31 @@ set_version("0.0a0")
 set_languages("c++17")
 set_targetdir(".")
 
-target("test")
+add_requires("entt 3.11", "libsdl 2.26", "libsdl_image 2.6", "fmt 10")
+add_includedirs("include", ".")
+
+
+target("main")
+	set_default(true)
 	set_kind("binary")
+	add_files("main.cpp")
+	add_files("src/**/*.cpp")
+
+	add_packages("entt", "libsdl", "libsdl_image", "fmt")
 	set_warnings("allextra")
+
+target("test")
+	set_default(false)
+	set_kind("binary")
+	set_prefixname("test-")
+
 	add_files("test/main.cpp")
 	add_files("test/cases/*.cpp")
-	add_includedirs(".")
+	add_files("src/**/*.cpp")
+
+	add_packages("entt", "fmt")
+
+	set_warnings("allextra")
 	set_optimize("none")
 	set_symbols("debug")
 	add_defines("DEBUG")
-	set_prefixname("test-")
\ No newline at end of file