From 117622cd4ae4238bc00b60e8fbccdcc5c0baa724 Mon Sep 17 00:00:00 2001
From: nanahi <130121847+na-na-hi@users.noreply.github.com>
Date: Tue, 2 Jan 2024 16:49:52 -0500
Subject: [PATCH] opengl/context_win: make --alpha=yes work

Specify cAlphaBits in PIXELFORMATDESCRIPTOR makes the pixel format
transparent, as is already the case for d3d11. Also makes the
window transparent when --alpha=yes is used.

Works on --vo=gpu and --vo=gpu-next.
---
 video/out/opengl/context_win.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/video/out/opengl/context_win.c b/video/out/opengl/context_win.c
index 968b1763bf..17b1cb491a 100644
--- a/video/out/opengl/context_win.c
+++ b/video/out/opengl/context_win.c
@@ -96,6 +96,8 @@ static bool create_dc(struct ra_ctx *ctx)
 
     pfd.iPixelType = PFD_TYPE_RGBA;
     pfd.cColorBits = 24;
+    if (ctx->opts.want_alpha)
+        pfd.cAlphaBits = 8;
     pfd.iLayerType = PFD_MAIN_PLANE;
     int pf = ChoosePixelFormat(hdc, &pfd);
 
@@ -293,6 +295,9 @@ static bool wgl_init(struct ra_ctx *ctx)
     if (!vo_w32_init(ctx->vo))
         goto fail;
 
+    if (ctx->opts.want_alpha)
+        vo_w32_set_transparency(ctx->vo, ctx->opts.want_alpha);
+
     vo_w32_run_on_thread(ctx->vo, create_ctx, ctx);
     if (!p->context)
         goto fail;