Fix analogue filter allocating/freeing surfaces every frame

This removes memory churn caused by using analogue mode.

The surfaces are only allocated if analogue mode is turned on, and kept
after they are initialized. Otherwise, if analogue mode is never turned
on (which will be the case for the vast majority of the time the game is
played), then no extra memory is used.

desktop_version/src/Graphics.cpp

@@ -171,6 +171,9 @@ void Graphics::destroy(void)
 #undef CLEAR_ARRAY
 }
 
+static SDL_Surface* tempFilterSrc = NULL;
+static SDL_Surface* tempFilterDest = NULL;
+
 void Graphics::create_buffers(void)
 {
 #define CREATE_TEXTURE_WITH_DIMENSIONS(w, h) \
@@ -212,6 +215,8 @@ void Graphics::destroy_buffers(void)
     VVV_freefunc(SDL_DestroyTexture, tempScrollingTexture);
     VVV_freefunc(SDL_DestroyTexture, towerbg.texture);
     VVV_freefunc(SDL_DestroyTexture, titlebg.texture);
+    VVV_freefunc(SDL_FreeSurface, tempFilterSrc);
+    VVV_freefunc(SDL_FreeSurface, tempFilterDest);
 }
 
 void Graphics::drawspritesetcol(int x, int y, int t, int c)
@@ -3153,7 +3158,7 @@ void Graphics::screenshake(void)
 {
     if (gameScreen.badSignalEffect)
     {
-        ApplyFilter();
+        ApplyFilter(tempFilterSrc, tempFilterDest);
     }
 
     set_render_target(menuoffTexture);
@@ -3191,7 +3196,7 @@ void Graphics::render(void)
 {
     if (gameScreen.badSignalEffect)
     {
-        ApplyFilter();
+        ApplyFilter(tempFilterSrc, tempFilterDest);
     }
 
     set_render_target(NULL);

desktop_version/src/GraphicsUtil.cpp

@@ -144,11 +144,17 @@ void UpdateFilter(void)
     }
 }
 
-void ApplyFilter(void)
+void ApplyFilter(SDL_Surface* src, SDL_Surface* dest)
 {
-    // Copy the screen to a temporary surface
-    SDL_Surface* src = SDL_CreateRGBSurface(0, SCREEN_WIDTH_PIXELS, SCREEN_HEIGHT_PIXELS, 32, 0, 0, 0, 0);
     if (src == NULL)
+    {
+        src = SDL_CreateRGBSurface(0, SCREEN_WIDTH_PIXELS, SCREEN_HEIGHT_PIXELS, 32, 0, 0, 0, 0);
+    }
+    if (dest == NULL)
+    {
+        dest = SDL_CreateRGBSurface(0, SCREEN_WIDTH_PIXELS, SCREEN_HEIGHT_PIXELS, 32, 0, 0, 0, 0);
+    }
+    if (src == NULL || dest == NULL)
     {
         return;
     }
@@ -161,18 +167,6 @@ void ApplyFilter(void)
         return;
     }
 
-    Uint32 rawFormat;
-
-    if (graphics.query_texture(graphics.gameTexture, &rawFormat, NULL, NULL, NULL) != 0)
-    {
-        return;
-    }
-
-    SDL_PixelFormat* format = SDL_AllocFormat(rawFormat);
-
-    // Have a second surface to do work on
-    SDL_Surface* dest = SDL_CreateRGBSurface(0, SCREEN_WIDTH_PIXELS, SCREEN_HEIGHT_PIXELS, 32, 0, 0, 0, 0);
-
     const int red_offset = rand() % 4;
 
     for (int x = 0; x < src->w; x++)
@@ -226,10 +220,5 @@ void ApplyFilter(void)
         }
     }
 
-    SDL_FreeFormat(format);
-
     SDL_UpdateTexture(graphics.gameTexture, NULL, dest->pixels, dest->pitch);
-
-    SDL_FreeSurface(src);
-    SDL_FreeSurface(dest);
 }

desktop_version/src/GraphicsUtil.h

@@ -12,6 +12,6 @@ void DrawPixel(SDL_Surface* surface, int x, int y, SDL_Color color);
 SDL_Color ReadPixel(const SDL_Surface* surface, int x, int y);
 
 void UpdateFilter(void);
-void ApplyFilter(void);
+void ApplyFilter(SDL_Surface* src, SDL_Surface* dest);
 
 #endif /* GRAPHICSUTIL_H */