--- a/src/window.c	Mon Jan 06 13:06:52 2020 +0100
+++ b/src/window.c	Mon Jan 06 20:20:58 2020 +0100
@@ -21,77 +21,63 @@
 #include <SDL.h>
 
 #include "window.h"
+#include "window_p.h"
 
-struct window {
-	SDL_Window *win;
-	SDL_Renderer *renderer;
+/* global object, used by textures */
+struct window win = {
+	.win = NULL,
+	.renderer = NULL
 };
 
-struct window *
+bool
 window_init(const char *title, unsigned width, unsigned height)
 {
-	struct window *w;
-
 	assert(title);
 
-	if (!(w = calloc(1, sizeof (struct window))))
-		return NULL;
 	if (SDL_CreateWindowAndRenderer(width, height, SDL_WINDOW_OPENGL,
-	    &w->win, &w->renderer) < 0)
-		goto fail;
+	    &win.win, &win.renderer) < 0)
+		return false;
 
-	SDL_SetWindowTitle(w->win, title);
-
-	return w;
+	SDL_SetWindowTitle(win.win, title);
 
-fail:
-	free(w);
-	return NULL;
+	return true;
 }
 
 uint32_t
-window_get_color(const struct window *w)
+window_get_color(void)
 {
-	assert(w);
-
 	Uint8 r = 0, g = 0, b = 0, a = 0;
 
-	SDL_GetRenderDrawColor(w->renderer, &r, &g, &b, &a);
+	SDL_GetRenderDrawColor(win.renderer, &r, &g, &b, &a);
 
 	return r << 24 | g << 16 | b << 8 | a;
 }
 
 void
-window_set_color(struct window *w, uint32_t color)
+window_set_color(uint32_t color)
 {
-	assert(w);
-
 	const Uint8 r = color >> 24 & 0xff;
 	const Uint8 g = color >> 16 & 0xff;
 	const Uint8 b = color >> 8  & 0xff;
 	const Uint8 a = color       & 0xff;
 
-	SDL_SetRenderDrawColor(w->renderer, r, g, b, a);
+	SDL_SetRenderDrawColor(win.renderer, r, g, b, a);
 }
 
 void
-window_draw_line(struct window *w, int x1, int y1, int x2, int y2)
+window_draw_line(int x1, int y1, int x2, int y2)
 {
-	assert(w);
-
-	SDL_RenderDrawLine(w->renderer, x1, y1, x2, y2);
+	SDL_RenderDrawLine(win.renderer, x1, y1, x2, y2);
 }
 
 void
-window_draw_point(struct window *w, int x1, int y1)
+window_draw_point(int x1, int y1)
 {
-	assert(w);
-
-	SDL_RenderDrawPoint(w->renderer, x1, y1);
+	SDL_RenderDrawPoint(win.renderer, x1, y1);
 }
 
 void
-window_draw_rectangle(struct window *w, bool fill, int x, int y, unsigned width, unsigned height)
+window_draw_rectangle(bool fill, int x, int y, unsigned width, unsigned height)
 {
 	const SDL_Rect rect = {
 		.w = width,
@@ -99,37 +85,30 @@
 		.x = x,
 		.y = y
 	};
-       
+
 	assert(w);
 
 	if (fill)
-		SDL_RenderFillRect(w->renderer, &rect);
+		SDL_RenderFillRect(win.renderer, &rect);
 	else
-		SDL_RenderDrawRect(w->renderer, &rect);
+		SDL_RenderDrawRect(win.renderer, &rect);
 }
 
 void
-window_clear(struct window *window)
+window_clear(void)
 {
-	assert(window);
-
-	SDL_RenderClear(window->renderer);
+	SDL_RenderClear(win.renderer);
 }
 
 void
-window_present(struct window *window)
+window_present(void)
 {
-	assert(window);
-
-	SDL_RenderPresent(window->renderer);
+	SDL_RenderPresent(win.renderer);
 }
 
 void
-window_close(struct window *w)
+window_close(void)
 {
-	assert(window);
-
-	SDL_DestroyRenderer(w->renderer);
-	SDL_DestroyWindow(w->win);
-	free(w);
+	SDL_DestroyRenderer(win.renderer);
+	SDL_DestroyWindow(win.win);
 }

--- a/src/window.h	Mon Jan 06 13:06:52 2020 +0100
+++ b/src/window.h	Mon Jan 06 20:20:58 2020 +0100
@@ -28,71 +28,56 @@
 #include <stdint.h>
 
 /**
- * \brief Window opaque object.
- */
-struct window;
-
-/**
  * Initialize window.
  *
  * \pre title != NULL
  * \param title the window title
  * \param width the desired width
  * \param height the desired height
- * \return the window or NULL on error
+ * \return true on success
  */
-struct window *
+bool
 window_init(const char *title, unsigned width, unsigned height);
 
 /**
  * Get the current drawing color.
  *
- * \pre window != NULL
- * \param window the window
  * \return the color in RRGGBBAA format
  */
 uint32_t
-window_get_color(const struct window *window);
+window_get_color(void);
 
 /**
  * Set the rendering drawing color.
  *
- * \pre window != NULL
- * \param window the window
  * \param color in RRGGBBAA format
  */
 void
-window_set_color(struct window *window, uint32_t color);
+window_set_color(uint32_t color);
 
 /**
  * Draw a line.
  *
- * \pre window != NULL
- * \param window the window
  * \param x1 first X coordinate
  * \param y1 first Y coordinate
  * \param x2 second X coordinate
  * \param y2 second Y coordinate
  */
 void
-window_draw_line(struct window *window, int x1, int y1, int x2, int y2);
+window_draw_line(int x1, int y1, int x2, int y2);
 
 /**
  * Draw a pixel point.
  *
- * \pre window != NULL
- * \param window the window
  * \param x the X coordinate
  * \param y the Y coordinate
  */
 void
-window_draw_point(struct window *window, int x, int y);
+window_draw_point(int x, int y);
 
 /**
  * Draw a rectangle
  *
- * \pre window != NULL
- * \param window the window
  * \param fill set to true to fill the rectangle
  * \param x the X coordinate
  * \param y the Y coordinate
@@ -100,39 +85,25 @@
  * \param h the rectangle height
  */
 void
-window_draw_rectangle(struct window *window,
-                      bool fill,
-                      int x,
-                      int y,
-                      unsigned w,
-                      unsigned h);
+window_draw_rectangle(bool fill, int x, int y, unsigned w, unsigned h);
 
 /**
  * Clear the window.
- *
- * \pre window != NULL
- * \param window the window
  */
 void
-window_clear(struct window *window);
+window_clear(void);
 
 /**
  * Present the window, only call this function one time in the main loop.
- *
- * \pre window != NULL
- * \param window the window
  */
 void
-window_present(struct window *window);
+window_present(void);
 
 /**
  * Close the window and destroy associated resources, do not use pointer
  * afterwards.
- *
- * \pre window != NULL
- * \param window the window
  */
 void
-window_close(struct window *window);
+window_close(void);
 
 #endif /* !MOLKO_WINDOW_H */

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/window_p.h	Mon Jan 06 20:20:58 2020 +0100
@@ -0,0 +1,32 @@
+/*
+ * window.c -- (PRIVATE) basic window management
+ *
+ * Copyright (c) 2020 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef MOLKO_WINDOW_P_H
+#define MOLKO_WINDOW_P_H
+
+#include <SDL.h>
+
+struct window {
+	SDL_Window *win;
+	SDL_Renderer *renderer;
+};
+
+/* Global window object */
+extern struct window win;
+
+#endif /* !MOLKO_WINDOW_P_H */