add underlay support to vulkan

Author: hunterk

gfx/common/vulkan_common.h

@@ -108,7 +108,8 @@ enum vk_flags
    VK_FLAG_READBACK_STREAMED   = (1 << 13),
    VK_FLAG_OVERLAY_ENABLE      = (1 << 14),
    VK_FLAG_OVERLAY_FULLSCREEN  = (1 << 15),
-   VK_FLAG_SDR_PIPELINE        = (1 << 16)
+   VK_FLAG_OVERLAY_BACKGROUND_FILL = (1 << 16),
+   VK_FLAG_SDR_PIPELINE        = (1 << 17)
 };
 
 enum vk_texture_type

gfx/drivers/vulkan.c

@@ -6761,7 +6761,18 @@ static bool vulkan_frame(void *data, const void *frame,
 #endif /* VULKAN_HDR_SWAPCHAIN */
 
 #ifdef HAVE_OVERLAY
-      if ((vk->flags & VK_FLAG_OVERLAY_ENABLE) && overlay_behind_menu)
+      /* Render background overlay (behind game viewport) */
+      if ((vk->flags & VK_FLAG_OVERLAY_ENABLE) && (vk->flags & VK_FLAG_OVERLAY_BACKGROUND_FILL))
+      {
+         uint64_t saved_flags = vk->flags & VK_FLAG_OVERLAY_FULLSCREEN;
+
+         vk->flags |= VK_FLAG_OVERLAY_FULLSCREEN;
+         vulkan_render_overlay(vk, video_width, video_height);
+
+         if (!saved_flags)
+            vk->flags &= ~VK_FLAG_OVERLAY_FULLSCREEN;
+      }
+      else if ((vk->flags & VK_FLAG_OVERLAY_ENABLE) && overlay_behind_menu)
          vulkan_render_overlay(vk, video_width, video_height);
 #endif
 
@@ -6818,7 +6829,8 @@ static bool vulkan_frame(void *data, const void *frame,
 #endif
 
 #ifdef HAVE_OVERLAY
-      if ((vk->flags & VK_FLAG_OVERLAY_ENABLE) && !overlay_behind_menu)
+      if ((vk->flags & VK_FLAG_OVERLAY_ENABLE) && !overlay_behind_menu
+            && !(vk->flags & VK_FLAG_OVERLAY_BACKGROUND_FILL))
          vulkan_render_overlay(vk, video_width, video_height);
 #endif
 
@@ -7965,6 +7977,18 @@ static void vulkan_overlay_full_screen(void *data, bool enable)
       vk->flags &= ~VK_FLAG_OVERLAY_FULLSCREEN;
 }
 
+static void vulkan_overlay_background_fill(void *data, bool enable)
+{
+   vk_t *vk = (vk_t*)data;
+   if (!vk)
+      return;
+
+   if (enable)
+      vk->flags |=  VK_FLAG_OVERLAY_BACKGROUND_FILL;
+   else
+      vk->flags &= ~VK_FLAG_OVERLAY_BACKGROUND_FILL;
+}
+
 static void vulkan_overlay_free(vk_t *vk)
 {
    int i;
@@ -8288,6 +8312,7 @@ static const video_overlay_interface_t vulkan_overlay_interface = {
    vulkan_overlay_vertex_geom,
    vulkan_overlay_full_screen,
    vulkan_overlay_set_alpha,
+   vulkan_overlay_background_fill,
 };
 
 static void vulkan_get_overlay_interface(void *data,