Added derivative textures

panda/src/glstuff/glShaderContext_src.cxx

@@ -362,6 +362,13 @@ update_shader_texture_bindings(CLP(ShaderContext) *prev, GSG *gsg)
         TextureStage *stage = gsg->_target._texture->get_on_stage(_cg_texbind[i].stage);
         tex = gsg->_target._texture->get_on_texture(stage);
       }
+      if (_cg_texbind[i].suffix != 0) {
+        // The suffix feature is inefficient. It is a temporary hack.
+        if (tex == 0) {
+          continue;
+        }
+        tex = tex->load_related(_cg_texbind[i].suffix);
+      }
       if ((tex == 0) || (tex->get_texture_type() != _cg_texbind[i].desiredtype)) {
         continue;
       }
@@ -824,11 +831,14 @@ compile_cg_parameter(CGparameter p)
   }
 
   if (pieces[0] == "tex") {
-    if ((!errchk_cg_parameter_words(p,2)) ||
-        (!errchk_cg_parameter_direction(p, CG_IN)) ||
+    if ((!errchk_cg_parameter_direction(p, CG_IN)) ||
         (!errchk_cg_parameter_variance(p, CG_UNIFORM)) ||
         (!errchk_cg_parameter_sampler(p)))
       return false;
+    if ((pieces.size() != 2)&&(pieces.size() != 3)) {
+      errchk_cg_output(p, "Invalid parameter name");
+      return false;
+    }
     ShaderTexBind bind;
     bind.parameter = p;
     bind.name = 0;
@@ -842,6 +852,9 @@ compile_cg_parameter(CGparameter p)
       errchk_cg_output(p, "Invalid type for a tex-parameter");
       return false;
     }
+    if (pieces.size()==3) {
+      bind.suffix = InternalName::make(((string)"-") + pieces[2]);
+    }
     _cg_texbind.push_back(bind);
     return true;
   }

panda/src/glstuff/glShaderContext_src.h

@@ -65,6 +65,7 @@ private:
     PT(InternalName) name;
     int stage;
     int desiredtype;
+    PT(InternalName) suffix;
   };
   struct ShaderTransBind {
     CGparameter parameter;

panda/src/gobj/texture.cxx

@@ -750,6 +750,45 @@ store(PNMImage &pnmimage, int z) const {
   return false;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: Texture::load_related
+//       Access: Published
+//  Description: Loads a texture whose filename is derived by
+//               concatenating a suffix to the filename of this
+//               texture.  May return NULL, for example, if this
+//               texture doesn't have a filename.
+////////////////////////////////////////////////////////////////////
+Texture *Texture::
+load_related(const PT(InternalName) &suffix) const {
+  RelatedTextures::const_iterator ti;
+  ti = _related_textures.find(suffix);
+  if (ti != _related_textures.end()) {
+    return (*ti).second;
+  }
+  if (!has_fullpath()) {
+    return (Texture*)NULL;
+  }
+  Filename main = get_fullpath();
+  main.set_basename_wo_extension(main.get_basename_wo_extension() + 
+                                 suffix->get_name());
+  Texture *res;
+  if (has_alpha_fullpath()) {
+    Filename alph = get_alpha_fullpath();
+    alph.set_basename_wo_extension(alph.get_basename_wo_extension() +
+                                   suffix->get_name());
+    res = TexturePool::load_texture(main, alph, 
+                                    _primary_file_num_channels,
+                                    _alpha_file_channel);
+  } else {
+    res = TexturePool::load_texture(main,
+                                    _primary_file_num_channels);
+  }
+  // I'm casting away the const-ness of 'this' because this
+  // field is only a cache.
+  ((Texture *)this)->_related_textures.insert(RelatedTextures::value_type(suffix, res));
+  return res;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: Texture::set_wrap_u
 //       Access: Published

panda/src/gobj/texture.h

@@ -24,6 +24,7 @@
 #include "filename.h"
 #include "typedWritableReferenceCount.h"
 #include "namable.h"
+#include "internalName.h"
 #include "graphicsStateGuardianBase.h"
 #include "pmap.h"
 
@@ -181,6 +182,8 @@ PUBLISHED:
   virtual bool load(const PNMImage &pnmimage, int z = 0);
   bool store(PNMImage &pnmimage, int z = 0) const;
 
+  Texture *load_related(const PT(InternalName) &suffix) const;
+  
   INLINE bool has_filename() const;
   INLINE const Filename &get_filename() const;
   INLINE bool has_alpha_filename() const;
@@ -353,6 +356,14 @@ protected:
   typedef pmap<PreparedGraphicsObjects *, TextureContext *> Contexts;
   Contexts _contexts;
 
+  // It is common, when using normal maps, specular maps, gloss maps,
+  // and such, to use a file naming convention where the filenames
+  // of the special maps are derived by concatenating a suffix to
+  // the name of the diffuse map.  The following table enables
+  // lookup of the special maps given the diffuse map and the suffix.
+  typedef pmap<PT(InternalName), PT(Texture)> RelatedTextures;
+  RelatedTextures _related_textures;
+
   // This value represents the intersection of all the dirty flags of
   // the various TextureContexts that might be associated with this
   // texture.