ShaderGenerator: prepare_scene now invokes shader generator.

This also necessarily removes ShaderGenerator's dependency on a host window.

panda/src/display/graphicsEngine.cxx

@@ -1849,16 +1849,6 @@ setup_scene(GraphicsStateGuardian *gsg, DisplayRegionPipelineReader *dr) {
   CPT(TransformState) cs_world_transform = cs_transform->compose(world_transform);
   scene_setup->set_cs_world_transform(cs_world_transform);
 
-  // Make sure that the GSG has a ShaderGenerator for the munger to use.  We
-  // have to do this here because the ShaderGenerator needs a host window
-  // pointer.  Hopefully we'll be able to eliminate that requirement in the
-  // future.
-#ifdef HAVE_CG
-  if (gsg->get_shader_generator() == NULL) {
-    gsg->set_shader_generator(new ShaderGenerator(gsg, window));
-  }
-#endif
-
   return scene_setup;
 }
 

panda/src/display/standardMunger.cxx

@@ -344,11 +344,11 @@ munge_state_impl(const RenderState *state) {
 #ifdef HAVE_CG
   if (_auto_shader) {
     CPT(RenderState) shader_state = munged_state->get_auto_shader_state();
-    ShaderGenerator *shader_generator = get_gsg()->get_shader_generator();
-    if (shader_generator == NULL) {
-      pgraph_cat.error()
-        << "auto_shader enabled, but GSG has no shader generator assigned!\n";
-      return munged_state;
+    GraphicsStateGuardian *gsg = get_gsg();
+    ShaderGenerator *shader_generator = gsg->get_shader_generator();
+    if (shader_generator == nullptr) {
+      shader_generator = new ShaderGenerator(gsg);
+      gsg->set_shader_generator(shader_generator);
     }
     if (shader_state->_generated_shader == NULL) {
       // Cache the generated ShaderAttrib on the shader state.

panda/src/pgraph/geomNode.cxx

@@ -15,6 +15,7 @@
 #include "geom.h"
 #include "geomTransformer.h"
 #include "sceneGraphReducer.h"
+#include "stateMunger.h"
 #include "accumulatedAttribs.h"
 #include "colorAttrib.h"
 #include "colorScaleAttrib.h"
@@ -391,33 +392,32 @@ r_prepare_scene(GraphicsStateGuardianBase *gsg, const RenderState *node_state,
       ((GeomPrimitive *)prim.p())->prepare(prepared_objects);
     }
 
+    if (munger->is_of_type(StateMunger::get_class_type())) {
+      StateMunger *state_munger = (StateMunger *)munger.p();
+      geom_state = state_munger->munge_state(geom_state);
+    }
+
     // And now prepare each of the textures.
-    const RenderAttrib *attrib =
-      geom_state->get_attrib(TextureAttrib::get_class_slot());
-    if (attrib != (const RenderAttrib *)NULL) {
-      const TextureAttrib *ta;
-      DCAST_INTO_V(ta, attrib);
+    const TextureAttrib *ta;
+    if (geom_state->get_attrib(ta)) {
       int num_stages = ta->get_num_on_stages();
       for (int i = 0; i < num_stages; ++i) {
         Texture *texture = ta->get_on_texture(ta->get_on_stage(i));
         // TODO: prepare the sampler states, if specified.
-        if (texture != (Texture *)NULL) {
+        if (texture != nullptr) {
           texture->prepare(prepared_objects);
         }
       }
     }
 
     // As well as the shaders.
-    attrib = geom_state->get_attrib(ShaderAttrib::get_class_slot());
-    if (attrib != (const RenderAttrib *)NULL) {
-      const ShaderAttrib *sa;
-      DCAST_INTO_V(sa, attrib);
+    const ShaderAttrib *sa;
+    if (geom_state->get_attrib(sa)) {
       Shader *shader = (Shader *)sa->get_shader();
-      if (shader != (Shader *)NULL) {
+      if (shader != nullptr) {
         shader->prepare(prepared_objects);
       }
-      // TODO: prepare the shader inputs.  TODO: Invoke the shader generator
-      // if enabled.
+      // TODO: prepare the shader inputs.
     }
   }
 

panda/src/pgraphnodes/shaderGenerator.cxx

@@ -55,8 +55,8 @@ TypeHandle ShaderGenerator::_type_handle;
  * shader generator belongs.
  */
 ShaderGenerator::
-ShaderGenerator(GraphicsStateGuardianBase *gsg, GraphicsOutputBase *host) :
-  _gsg(gsg), _host(host) {
+ShaderGenerator(GraphicsStateGuardianBase *gsg) :
+  _gsg(gsg) {
 
   // The ATTR# input semantics seem to map to generic vertex attributes in
   // both arbvp1 and glslv, which behave more consistently.  However, they

panda/src/pgraphnodes/shaderGenerator.h

@@ -60,7 +60,7 @@ class GeomVertexAnimationSpec;
  */
 class EXPCL_PANDA_PGRAPHNODES ShaderGenerator : public TypedReferenceCount {
 PUBLISHED:
-  ShaderGenerator(GraphicsStateGuardianBase *gsg, GraphicsOutputBase *host);
+  ShaderGenerator(GraphicsStateGuardianBase *gsg);
   virtual ~ShaderGenerator();
   virtual CPT(ShaderAttrib) synthesize_shader(const RenderState *rs,
                                               const GeomVertexAnimationSpec &anim);
@@ -144,7 +144,6 @@ protected:
 
   // This is not a PT() to prevent a circular reference.
   GraphicsStateGuardianBase *_gsg;
-  GraphicsOutputBase *_host;
 
 public:
   static TypeHandle get_class_type() {