From ff39749feb776c6ca4e30bddcac8a75ebfeaa39a Mon Sep 17 00:00:00 2001
From: Dagen Brock <dagenbrock@gmail.com>
Date: Sun, 26 Aug 2018 13:59:39 -0500
Subject: [PATCH] fix sdl frame rendering vsync method to simply present the
 buffer once per frame

---
 src/sdl2_driver.c | 25 +++++++++++++++----------
 src/video.c       | 12 ++++--------
 2 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/src/sdl2_driver.c b/src/sdl2_driver.c
index c9558cb..8db6530 100644
--- a/src/sdl2_driver.c
+++ b/src/sdl2_driver.c
@@ -416,17 +416,9 @@ void sdl_push_kimage(Kimage *kimage_ptr, int destx, int desty, int srcx, int src
     pitch = BORDER_WIDTH+72;
   }
   SDL_UpdateTexture(texture, &dstrect, src_ptr, pitch*4 );
-  SDL_RenderClear(renderer);
-  SDL_RenderCopy(renderer, texture, NULL, NULL);
-  if (g_scanline_simulator) {
-    SDL_RenderCopy(renderer, overlay_texture, NULL, NULL);
-  }
-  SDL_RenderPresent(renderer);
 
-  if (g_screenshot_requested) {
-    x_take_screenshot();
-    g_screenshot_requested = 0;
-  }
+  // We now call the render step seperately in sdl_present_buffer once per frame
+  // SDL picks up the buffer and waits for VBLANK to send it
 }
 
 
@@ -806,6 +798,19 @@ void debuginfo_renderer(SDL_Renderer *r) {
   }
 }
 
+void sdl_present_buffer() {
+  SDL_RenderClear(renderer);
+  SDL_RenderCopy(renderer, texture, NULL, NULL);
+  if (g_scanline_simulator) {
+    SDL_RenderCopy(renderer, overlay_texture, NULL, NULL);
+  }
+
+  SDL_RenderPresent(renderer);
+  if (g_screenshot_requested) {
+    x_take_screenshot();
+    g_screenshot_requested = 0;
+  }
+}
 
 // BELOW ARE FUNCTIONS THAT ARE EITHER UNIMPLEMENTED, OR AR NOT RELEVANT TO
 // THIS DRIVER.
diff --git a/src/video.c b/src/video.c
index 7e0c376..72b96f0 100644
--- a/src/video.c
+++ b/src/video.c
@@ -640,7 +640,10 @@ void video_update() {
     video_update_through_line(0);
   }
 
-
+#if defined(HAVE_SDL)
+  extern void sdl_present_buffer();
+  sdl_present_buffer();
+#endif
 // OG Notify host that video has been uodated
 #if defined(ACTIVEGSPLUGIN) && defined(MAC)
   {
@@ -3474,13 +3477,6 @@ void video_update_color_array(int col_num, int a2_color)      {
     return;
   }
 
-#if 0
-  if(g_screen_depth != 8) {
-    /* redraw whole superhires for now */
-    g_full_refresh_needed = -1;
-  }
-#endif
-
   video_update_color_raw(col_num, a2_color);
 }