add max-texture-stages

panda/src/display/config_display.cxx

@@ -132,6 +132,17 @@ ConfigVariableBool prefer_single_buffer
           "false (since in that case the buffer can share a graphics context "
           "with the window)."));
 
+ConfigVariableInt max_texture_stages
+("max-texture-stages", -1,
+ PRC_DESC("Set this to a positive integer to limit the number of "
+          "texture stages reported by the GSG.  This can be used to limit "
+          "the amount of multitexturing Panda will attempt to use.  "
+          "If this is zero or less, the GSG will report its honest number "
+          "of texture stages, allowing Panda the full use of the graphics "
+          "card; if it is 1 or more, then Panda will never allow more than "
+          "this number of texture stages simultaneously, regardless of "
+          "what the GSG says it can do."));
+
 ConfigVariableBool support_render_texture
 ("support-render-texture", true,
  PRC_DESC("Set this true allow use of the render-to-a-texture feature, if it "

panda/src/display/config_display.h

@@ -49,6 +49,7 @@ extern EXPCL_PANDA_DISPLAY ConfigVariableBool prefer_texture_buffer;
 extern EXPCL_PANDA_DISPLAY ConfigVariableBool prefer_parasite_buffer;
 extern EXPCL_PANDA_DISPLAY ConfigVariableBool prefer_single_buffer;
 
+extern EXPCL_PANDA_DISPLAY ConfigVariableInt max_texture_stages;
 extern EXPCL_PANDA_DISPLAY ConfigVariableBool support_render_texture;
 extern EXPCL_PANDA_DISPLAY ConfigVariableBool support_rescale_normal;
 extern EXPCL_PANDA_DISPLAY ConfigVariableBool copy_texture_inverted;

panda/src/display/graphicsStateGuardian.I

@@ -277,6 +277,9 @@ get_max_vertices_per_primitive() const {
 ////////////////////////////////////////////////////////////////////
 INLINE int GraphicsStateGuardian::
 get_max_texture_stages() const {
+  if (max_texture_stages > 0) {
+    return min(_max_texture_stages, (int)max_texture_stages);
+  }
   return _max_texture_stages;
 }
 

panda/src/display/graphicsStateGuardian.cxx

@@ -2068,7 +2068,8 @@ void GraphicsStateGuardian::
 determine_effective_texture() {
   nassertv(_target._texture != (TextureAttrib *)NULL &&
            _target._tex_gen != (TexGenAttrib *)NULL);
-  _effective_texture = _target._texture->filter_to_max(_max_texture_stages);
+  int max_texture_stages = get_max_texture_stages();
+  _effective_texture = _target._texture->filter_to_max(max_texture_stages);
   _effective_tex_gen = _target._tex_gen;
   
   if (_has_texture_alpha_scale) {
@@ -2080,7 +2081,7 @@ determine_effective_texture() {
                                (stage, TexGenAttrib::M_constant, TexCoord3f(_current_color_scale[3], 0.0f, 0.0f)));
   }
 
-  nassertv(_effective_texture->get_num_on_stages() <= _max_texture_stages);
+  nassertv(_effective_texture->get_num_on_stages() <= max_texture_stages);
 }
 
 ////////////////////////////////////////////////////////////////////