From bd4dc8a379d668075609303652842d533d7fee74 Mon Sep 17 00:00:00 2001
From: rdb <git@rdb.name>
Date: Thu, 10 Oct 2024 19:57:42 +0200
Subject: [PATCH] display: Fix ability to copy wdxGraphicsBuffer to RAM on DX9

---
 panda/src/display/frameBufferProperties.cxx | 11 ++++++-----
 panda/src/dxgsg9/wdxGraphicsBuffer9.cxx     |  7 ++++---
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/panda/src/display/frameBufferProperties.cxx b/panda/src/display/frameBufferProperties.cxx
index c6e1e9353f..4f27007cbc 100644
--- a/panda/src/display/frameBufferProperties.cxx
+++ b/panda/src/display/frameBufferProperties.cxx
@@ -305,11 +305,12 @@ int FrameBufferProperties::
 get_buffer_mask() const {
   int mask = 0;
 
-  if (_property[FBP_back_buffers] > 0) {
-    mask = RenderBuffer::T_front | RenderBuffer::T_back;
-  } else {
-    mask = RenderBuffer::T_front;
-  }
+  //XXX rdb: some buffers only have a front buffer, some only a back buffer
+  //if (_property[FBP_back_buffers] > 0) {
+     mask = RenderBuffer::T_front | RenderBuffer::T_back;
+  //} else {
+  //  mask = RenderBuffer::T_front;
+  //}
   if (_property[FBP_depth_bits] > 0) {
     mask |= RenderBuffer::T_depth;
   }
diff --git a/panda/src/dxgsg9/wdxGraphicsBuffer9.cxx b/panda/src/dxgsg9/wdxGraphicsBuffer9.cxx
index 03d5a1a41a..d43febe03e 100644
--- a/panda/src/dxgsg9/wdxGraphicsBuffer9.cxx
+++ b/panda/src/dxgsg9/wdxGraphicsBuffer9.cxx
@@ -45,9 +45,10 @@ wdxGraphicsBuffer9(GraphicsEngine *engine, GraphicsPipe *pipe,
   _color_backing_store = nullptr;
   _depth_backing_store = nullptr;
 
-  // is this correct ??? Since the pbuffer never gets flipped, we get
-  // screenshots from the same buffer we draw into.
-  _screenshot_buffer_type = _draw_buffer_type;
+  // Since the pbuffer never gets flipped, we get screenshots from the same
+  // buffer we draw into, which is the back buffer.
+  _draw_buffer_type = RenderBuffer::T_back;
+  _screenshot_buffer_type = RenderBuffer::T_back;
 
   _shared_depth_buffer = 0;
   _debug = 0;