From 58f547bfe1488b104e5483997324d3fe3c4e3c78 Mon Sep 17 00:00:00 2001
From: Jamiras <32680403+Jamiras@users.noreply.github.com>
Date: Wed, 16 Aug 2023 15:17:54 -0600
Subject: [PATCH] disallow video_swap_interval and black_frame_insertion in
 hardcore (#15605)

---
 cheevos/cheevos.c   | 36 ++++++++++++++++++++++++++++++++++++
 menu/menu_setting.c |  2 ++
 2 files changed, 38 insertions(+)

diff --git a/cheevos/cheevos.c b/cheevos/cheevos.c
index ee80a65ab6..9558a0dfad 100644
--- a/cheevos/cheevos.c
+++ b/cheevos/cheevos.c
@@ -1153,6 +1153,12 @@ void rcheevos_validate_config_settings(void)
    if (!sysinfo->library_name || !rcheevos_locals.hardcore_active)
       return;
 
+   /* this adds a sleep to every frame. if the value is high enough that a
+    * single frame takes more than 1/60th of a second to evaluate, render,
+    * and sleep, then the real framerate is less than 60fps. with vsync on,
+    * it'll wait for the next vsync event, effectively halfing the fps. the
+    * auto setting should achieve the most accurate frame rate anyway, so
+    * disallow any manual values */
    if (!settings->bools.video_frame_delay_auto && settings->uints.video_frame_delay != 0) {
       const char* error = "Hardcore paused. Manual video frame delay setting not allowed.";
       CHEEVOS_LOG(RCHEEVOS_TAG "%s\n", error);
@@ -1163,6 +1169,36 @@ void rcheevos_validate_config_settings(void)
       return;
    }
 
+   /* this specifies how many vsync events should occur for each rendered
+    * frame. if vsync is on for a 60Hz monitor and swap_interval is 2 (only
+    * update every other vsync), only 30fps will be generated. for a 144Hz
+    * monitor, a value of 2 will generate 72fps, which is still faster than
+    * the expected 60fps, so the user should really be using auto (0).
+    * allow 1 even though that could be potentially abused on monitors
+    * running at less than 60Hz because 1 is the default value - many users
+    * wouldn't know how to change it to auto. */
+   if (settings->uints.video_swap_interval > 1) {
+      const char* error = "Hardcore paused. vsync swap interval above 1 not allowed.";
+      CHEEVOS_LOG(RCHEEVOS_TAG "%s\n", error);
+      rcheevos_pause_hardcore();
+
+      runloop_msg_queue_push(error, 0, 4 * 60, false, NULL,
+         MESSAGE_QUEUE_ICON_DEFAULT, MESSAGE_QUEUE_CATEGORY_WARNING);
+      return;
+   }
+
+   /* this causes N blank frames to be rendered between real frames, thus
+    * slowing down the actual number of rendered frames per second. */
+   if (settings->uints.video_black_frame_insertion > 0) {
+      const char* error = "Hardcore paused. Black frame insertion not allowed.";
+      CHEEVOS_LOG(RCHEEVOS_TAG "%s\n", error);
+      rcheevos_pause_hardcore();
+
+      runloop_msg_queue_push(error, 0, 4 * 60, false, NULL,
+         MESSAGE_QUEUE_ICON_DEFAULT, MESSAGE_QUEUE_CATEGORY_WARNING);
+      return;
+   }
+
    if (!(disallowed_settings
             = rc_libretro_get_disallowed_settings(sysinfo->library_name)))
       return;
diff --git a/menu/menu_setting.c b/menu/menu_setting.c
index 33b2eee85e..ca2d8399d2 100644
--- a/menu/menu_setting.c
+++ b/menu/menu_setting.c
@@ -8034,6 +8034,8 @@ static void general_write_handler(rarch_setting_t *setting)
 #ifdef HAVE_CHEEVOS
       case MENU_ENUM_LABEL_VIDEO_FRAME_DELAY:
       case MENU_ENUM_LABEL_VIDEO_FRAME_DELAY_AUTO:
+      case MENU_ENUM_LABEL_VIDEO_SWAP_INTERVAL:
+      case MENU_ENUM_LABEL_VIDEO_BLACK_FRAME_INSERTION:
          rcheevos_validate_config_settings();
          break;
 #endif