From 25a0389533899aa3216d7d89165bc2eba0c690c1 Mon Sep 17 00:00:00 2001
From: David Rose <david@ddrose.com>
Date: Tue, 13 Mar 2001 23:28:01 +0000
Subject: [PATCH] *** empty log message ***

---
 panda/src/display/graphicsStateGuardian.cxx | 23 +++++++++++++++++++++
 panda/src/display/graphicsStateGuardian.h   |  3 +++
 panda/src/dxgsg/dxGraphicsStateGuardian.cxx | 12 ++++++-----
 panda/src/glgsg/glGraphicsStateGuardian.cxx | 20 ++++++++----------
 4 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/panda/src/display/graphicsStateGuardian.cxx b/panda/src/display/graphicsStateGuardian.cxx
index 768e30ea20..95cf2cc4e6 100644
--- a/panda/src/display/graphicsStateGuardian.cxx
+++ b/panda/src/display/graphicsStateGuardian.cxx
@@ -94,6 +94,7 @@ reset() {
   _depth_clear_value = 1.0;
   _stencil_clear_value = 0.0;
   _accum_clear_value.set(0.0, 0.0, 0.0, 0.0);
+  _clear_buffer_type = RenderBuffer::T_back | RenderBuffer::T_depth;
   _normals_enabled = false;
 }
 
@@ -330,6 +331,28 @@ set_accum_clear_value(const Colorf& value) {
   _accum_clear_value = value;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: GraphicsStateGuardian::enable_frame_clear
+//       Access: Public
+//  Description: Activates or deactivates the automatic clearing of
+//               the frame buffer and/or depth buffer at the beginning
+//               of each frame.
+//
+//               If clear_color is true, the color buffer will be
+//               cleared; if clear_depth is true, the depth buffer
+//               will be cleared.
+////////////////////////////////////////////////////////////////////
+void GraphicsStateGuardian::
+enable_frame_clear(bool clear_color, bool clear_depth) {
+  _clear_buffer_type = 0;
+  if (clear_color) {
+    _clear_buffer_type |= RenderBuffer::T_back;
+  }
+  if (clear_depth) {
+    _clear_buffer_type |= RenderBuffer::T_depth;
+  }
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: GraphicsStateGuardian::wants_normals
 //       Access: Public, Virtual
diff --git a/panda/src/display/graphicsStateGuardian.h b/panda/src/display/graphicsStateGuardian.h
index a12c049e89..7955af2b5b 100644
--- a/panda/src/display/graphicsStateGuardian.h
+++ b/panda/src/display/graphicsStateGuardian.h
@@ -62,6 +62,8 @@ PUBLISHED:
     return _accum_clear_value;
   }
 
+  void enable_frame_clear(bool clear_color, bool clear_depth);
+
 public:
   void release_all_textures();
 
@@ -138,6 +140,7 @@ protected:
   float _depth_clear_value;
   bool _stencil_clear_value;
   Colorf _accum_clear_value;
+  int _clear_buffer_type;
 
   int _display_region_stack_level;
   int _frame_buffer_stack_level;
diff --git a/panda/src/dxgsg/dxGraphicsStateGuardian.cxx b/panda/src/dxgsg/dxGraphicsStateGuardian.cxx
index 5217de74d5..7bc3e5976b 100644
--- a/panda/src/dxgsg/dxGraphicsStateGuardian.cxx
+++ b/panda/src/dxgsg/dxGraphicsStateGuardian.cxx
@@ -639,11 +639,13 @@ render_frame(const AllAttributesWrapper &initial_state) {
 
 	_decal_level = 0;
 
-	// First, clear the entire window.
-	PT(DisplayRegion) win_dr = 
-	_win->make_scratch_display_region(_win->get_width(), _win->get_height());
-	clear(get_render_buffer(RenderBuffer::T_back | RenderBuffer::T_depth), win_dr);
-
+	if (_clear_buffer_type != 0) {
+	  // First, clear the entire window.
+	  PT(DisplayRegion) win_dr = 
+	    _win->make_scratch_display_region(_win->get_width(), _win->get_height());
+	  clear(get_render_buffer(_clear_buffer_type), win_dr);
+	}
+	  
 	// Now render each of our layers in order.
 	int max_channel_index = _win->get_max_channel_index();
 	for (int c = 0; c < max_channel_index; c++) {
diff --git a/panda/src/glgsg/glGraphicsStateGuardian.cxx b/panda/src/glgsg/glGraphicsStateGuardian.cxx
index 76af81aed6..3ae9be9307 100644
--- a/panda/src/glgsg/glGraphicsStateGuardian.cxx
+++ b/panda/src/glgsg/glGraphicsStateGuardian.cxx
@@ -463,18 +463,16 @@ render_frame(const AllAttributesWrapper &initial_state) {
   _win->begin_frame();
   _decal_level = 0;
 
-  // First, clear the entire window.
-  PT(DisplayRegion) win_dr = 
-    _win->make_scratch_display_region(_win->get_width(), _win->get_height());
-  if (win_dr == (DisplayRegion*)NULL)
-  {
-    cerr << "null scratch " << endl;
-    exit(0);
+  if (_clear_buffer_type != 0) {
+    // First, clear the entire window.
+    PT(DisplayRegion) win_dr = 
+      _win->make_scratch_display_region(_win->get_width(), _win->get_height());
+    nassertv(win_dr != (DisplayRegion*)NULL);
+    DisplayRegionStack old_dr = push_display_region(win_dr);
+    prepare_display_region();
+    clear(get_render_buffer(_clear_buffer_type));
+    pop_display_region(old_dr);
   }
-  DisplayRegionStack old_dr = push_display_region(win_dr);
-  prepare_display_region();
-  clear(get_render_buffer(RenderBuffer::T_back | RenderBuffer::T_depth));
-  pop_display_region(old_dr);
 
   // Now render each of our layers in order.
   int max_channel_index = _win->get_max_channel_index();