ogc: reduces number of copies from EFB to texture

Instead of copying at the end of every command queue flush, copy the EFB
to the texture only when the texture stops being a render target.

Unfortunately SDL invokes the SetRenderTarget() method after having
updated the render target pointer, forcing us to keep our own copy of
it.

Author: mardy

src/render/ogc/SDL_render_ogc.c

@@ -44,6 +44,7 @@ typedef struct
     int ops_after_present;
     bool vsync;
     u8 efb_pixel_format;
+    SDL_Texture *render_target;
 } OGC_RenderData;
 
 typedef struct
@@ -101,9 +102,8 @@ static inline void OGC_SetBlendMode(SDL_Renderer *renderer, SDL_BlendMode blend_
     set_blend_mode_real(renderer, blend_mode);
 }
 
-static void save_efb_to_texture(SDL_Renderer *renderer)
+static void save_efb_to_texture(SDL_Texture *texture)
 {
-    SDL_Texture *texture = renderer->target;
     OGC_TextureData *ogc_tex = texture->driverdata;
 
     GX_SetTexCopySrc(0, 0, texture->w, texture->h);
@@ -218,8 +218,12 @@ static int OGC_SetRenderTarget(SDL_Renderer *renderer, SDL_Texture *texture)
         if (SDL_ISPIXELFORMAT_ALPHA(texture->format)) {
             desired_efb_pixel_format = GX_PF_RGBA6_Z24;
         }
+    } else if (data->render_target) {
+        save_efb_to_texture(data->render_target);
     }
 
+    data->render_target = texture;
+
     if (desired_efb_pixel_format != data->efb_pixel_format) {
         data->efb_pixel_format = desired_efb_pixel_format;
         GX_SetPixelFmt(data->efb_pixel_format, GX_ZC_LINEAR);
@@ -525,10 +529,6 @@ static int OGC_RunCommandQueue(SDL_Renderer *renderer, SDL_RenderCommand *cmd, v
         cmd = cmd->next;
     }
 
-    if (renderer->target) {
-        save_efb_to_texture(renderer);
-    }
-
     return 0;
 }