Started on adaptive aspect ratio adjustment.

Just one problem: the backgrounds don't get resized and so you get
awful mush on the right side/bottom of the screen. Will fix in
the next commit.

src/engine.c

@@ -270,12 +270,7 @@ void engine_setMode()
 	engine.useMusic = useMusic;
 	engine.autoPause = autoPause;
 
-	screen = SDL_CreateRGBSurface(0, DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT, 32, 0xff0000, 0xff00, 0xff, 0xff000000);
-	if (screen == NULL)
-	{
-		printf("Couldn't create %ix%ix32 surface: %s\n", DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT, SDL_GetError());
-		exit(1);
-	}
+	screen_adjustDimensions(DEFAULT_SCREEN_WIDTH, DEFAULT_SCREEN_HEIGHT);
 
 	window = SDL_CreateWindow("Project: Starfighter",
 		SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
@@ -289,21 +284,7 @@ void engine_setMode()
 	SDL_SetWindowIcon(window, gfx_loadImage("gfx/alienDevice.png"));
 	SDL_SetWindowFullscreen(window, engine.fullScreen ? FULLSCREEN : 0);
 
-	renderer = SDL_CreateRenderer(window, -1, 0);
-	if (renderer == NULL)
-	{
-		printf("Could not create renderer: %s\n", SDL_GetError());
-		exit(1);
-	}
-
-	SDL_RenderSetLogicalSize(renderer, screen->w, screen->h);
-
-	renderer_texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_STREAMING, screen->w, screen->h);
-	if (renderer_texture == NULL)
-	{
-		printf("Couldn't create %ix%ix32 texture: %s\n", screen->w, screen->h, SDL_GetError());
-		exit(1);
-	}
+	renderer_reset();
 
 #ifndef NOSOUND
 	if (engine.useAudio)

src/player.c

@@ -337,6 +337,8 @@ void player_getInput()
 			case SDL_WINDOWEVENT:
 				if (engine.event.window.event == SDL_WINDOWEVENT_SIZE_CHANGED)
 				{
+					screen_adjustDimensions(engine.event.window.data1, engine.event.window.data2);
+					renderer_reset();
 					screen_clear(black);
 					renderer_update();
 					screen_clear(black);

src/renderer.c

@@ -23,6 +23,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "structs.h"
 
 #include "screen.h"
+#include "window.h"
 
 SDL_Renderer *renderer;
 SDL_Texture *renderer_texture;
@@ -36,3 +37,28 @@ void renderer_update()
 	SDL_RenderCopy(renderer, renderer_texture, NULL, NULL);
 	SDL_RenderPresent(renderer);
 }
+
+// Call after screen_adjustDimensions.
+void renderer_reset()
+{
+	if (renderer == NULL)
+	{
+		renderer = SDL_CreateRenderer(window, -1, 0);
+		if (renderer == NULL)
+		{
+			printf("Could not create renderer: %s\n", SDL_GetError());
+			exit(1);
+		}
+	}
+	SDL_RenderSetLogicalSize(renderer, screen->w, screen->h);
+
+	if (renderer_texture != NULL)
+		SDL_DestroyTexture(renderer_texture);
+
+	renderer_texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_STREAMING, screen->w, screen->h);
+	if (renderer_texture == NULL)
+	{
+		printf("Couldn't create %ix%ix32 texture: %s\n", screen->w, screen->h, SDL_GetError());
+		exit(1);
+	}
+}

src/renderer.h

@@ -29,5 +29,6 @@ extern SDL_Renderer *renderer;
 extern SDL_Texture *renderer_texture;
 
 void renderer_update();
+void renderer_reset();
 
 #endif

src/screen.c

@@ -133,3 +133,43 @@ void screen_drawRect(int x, int y, int w, int h, Uint8 red, Uint8 green, Uint8 b
 {
 	gfx_drawRect(screen, x, y, w, h, red, green, blue);
 }
+
+/*
+Adjust the dimensions of the screen to match the aspect ratio of the
+window, using DEFAULT_SCREEN_WIDTH and DEFAULT_SCREEN_HEIGHT as a
+baseline.
+*/
+void screen_adjustDimensions(int w, int h)
+{
+	double default_ratio = (double)DEFAULT_SCREEN_WIDTH / (double)DEFAULT_SCREEN_HEIGHT;
+	double new_ratio = (double)w / (double)h;
+	
+	// Calculate dimensions
+	if (new_ratio > default_ratio)
+	{
+		// Wide screen
+		w = (DEFAULT_SCREEN_HEIGHT * w) / h;
+		h = DEFAULT_SCREEN_HEIGHT;
+	}
+	else
+	{
+		// Tall screen
+		w = DEFAULT_SCREEN_WIDTH;
+		h = (DEFAULT_SCREEN_WIDTH * h) / w;
+	}
+	
+	// Free previous surface (if it exists)
+	if (screen != NULL)
+	{
+		SDL_FreeSurface(screen);
+		screen = NULL;
+	}
+	
+	// Create the surface
+	screen = SDL_CreateRGBSurface(0, w, h, 32, 0xff0000, 0xff00, 0xff, 0xff000000);
+	if (screen == NULL)
+	{
+		printf("Couldn't create %ix%ix32 surface: %s\n", w, h, SDL_GetError());
+		exit(1);
+	}
+}

src/screen.h

@@ -38,5 +38,6 @@ void screen_flushBuffer();
 void screen_unBuffer();
 void screen_clear(Uint32 color);
 void screen_drawRect(int x, int y, int w, int h, Uint8 red, Uint8 green, Uint8 blue);
+void screen_adjustDimensions(int w, int h);
 
 #endif