Backport shadow-depth-bits config var to 1.9

doc/ReleaseNotes

@@ -17,6 +17,7 @@ This issue fixes several bugs that were still found in 1.9.2.
 * Improve performance of texture load and store operations
 * Fix crashes with pbuffers on Intel cards on Windows
 * Support for Autodesk Maya 2016.5
+* Add shadow-depth-bits config var to control shadow map depth
 
 ------------------------  RELEASE 1.9.2  ------------------------
 

panda/src/display/config_display.cxx

@@ -445,6 +445,12 @@ ConfigVariableDouble pixel_zoom
 ("pixel-zoom", 1.0,
  PRC_DESC("The default pixel_zoom factor for new windows."));
 
+ConfigVariableInt shadow_depth_bits
+("shadow-depth-bits", 1,
+ PRC_DESC("The minimum number of depth buffer bits requested when rendering "
+          "shadow maps.  Set this to 32 for more depth resolution in shadow "
+          "maps."));
+
 ConfigVariableColor background_color
 ("background-color", "0.41 0.41 0.41 0.0",
  PRC_DESC("Specifies the rgb(a) value of the default background color for a "

panda/src/display/config_display.h

@@ -102,6 +102,7 @@ extern EXPCL_PANDA_DISPLAY ConfigVariableInt stencil_bits;
 extern EXPCL_PANDA_DISPLAY ConfigVariableInt accum_bits;
 extern EXPCL_PANDA_DISPLAY ConfigVariableInt multisamples;
 extern EXPCL_PANDA_DISPLAY ConfigVariableInt back_buffers;
+extern EXPCL_PANDA_DISPLAY ConfigVariableInt shadow_depth_bits;
 
 extern EXPCL_PANDA_DISPLAY ConfigVariableDouble pixel_zoom;
 

panda/src/display/graphicsStateGuardian.cxx

@@ -3176,13 +3176,17 @@ make_shadow_buffer(const NodePath &light_np, GraphicsOutputBase *host) {
 
   nassertr(light->_sbuffers.count(this) == 0, NULL);
 
-  display_cat.debug() << "Constructing shadow buffer for light '" << light->get_name()
-    << "', size=" << light->_sb_xsize << "x" << light->_sb_ysize
-    << ", sort=" << light->_sb_sort << "\n";
+  if (display_cat.is_debug()) {
+    display_cat.debug()
+      << "Constructing shadow buffer for light '" << light->get_name()
+      << "', size=" << light->_sb_xsize << "x" << light->_sb_ysize
+      << ", sort=" << light->_sb_sort << "\n";
+  }
 
-  // Setup some flags and properties
+  // Determine the properties for creating the depth buffer.
   FrameBufferProperties fbp;
-  fbp.set_depth_bits(1); // We only need depth
+  fbp.set_depth_bits(shadow_depth_bits);
+
   WindowProperties props = WindowProperties::size(light->_sb_xsize, light->_sb_ysize);
   int flags = GraphicsPipe::BF_refuse_window;
   if (is_point) {