fix flatten in conjunction with billboards

panda/src/pgraph/billboardEffect.cxx

@@ -61,6 +61,22 @@ safe_to_transform() const {
   return false;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: BillboardEffect::prepare_flatten_transform
+//       Access: Public, Virtual
+//  Description: Preprocesses the accumulated transform that is about
+//               to be applied to (or through) this node due to a
+//               flatten operation.  The returned value will be used
+//               instead.
+////////////////////////////////////////////////////////////////////
+CPT(TransformState) BillboardEffect::
+prepare_flatten_transform(const TransformState *net_transform) const {
+  // We don't want any flatten operation to rotate the billboarded
+  // node, since the billboard effect should eat any rotation that
+  // comes in from above.
+  return net_transform->set_hpr(LVecBase3f(0, 0, 0));
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: BillboardEffect::output
 //       Access: Public, Virtual

panda/src/pgraph/billboardEffect.h

@@ -56,6 +56,7 @@ PUBLISHED:
 
 public:
   virtual bool safe_to_transform() const;
+  virtual CPT(TransformState) prepare_flatten_transform(const TransformState *net_transform) const;
   virtual void output(ostream &out) const;
 
   virtual bool has_cull_callback() const;

panda/src/pgraph/renderEffect.cxx

@@ -102,6 +102,19 @@ safe_to_transform() const {
   return true;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: RenderEffect::prepare_flatten_transform
+//       Access: Public, Virtual
+//  Description: Preprocesses the accumulated transform that is about
+//               to be applied to (or through) this node due to a
+//               flatten operation.  The returned value will be used
+//               instead.
+////////////////////////////////////////////////////////////////////
+CPT(TransformState) RenderEffect::
+prepare_flatten_transform(const TransformState *net_transform) const {
+  return net_transform;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: RenderEffect::safe_to_combine
 //       Access: Public, Virtual

panda/src/pgraph/renderEffect.h

@@ -67,6 +67,7 @@ public:
   virtual ~RenderEffect();
 
   virtual bool safe_to_transform() const;
+  virtual CPT(TransformState) prepare_flatten_transform(const TransformState *net_transform) const;
   virtual bool safe_to_combine() const;
   virtual CPT(RenderEffect) xform(const LMatrix4f &mat) const;
 

panda/src/pgraph/renderEffects.cxx

@@ -109,6 +109,26 @@ safe_to_transform() const {
   return true;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: RenderEffects::prepare_flatten_transform
+//       Access: Public, Virtual
+//  Description: Preprocesses the accumulated transform that is about
+//               to be applied to (or through) this node due to a
+//               flatten operation.  The returned value will be used
+//               instead.
+////////////////////////////////////////////////////////////////////
+CPT(TransformState) RenderEffects::
+prepare_flatten_transform(const TransformState *net_transform) const {
+  CPT(TransformState) result = net_transform;
+  Effects::const_iterator ai;
+  for (ai = _effects.begin(); ai != _effects.end(); ++ai) {
+    const Effect &effect = (*ai);
+    result = effect._effect->prepare_flatten_transform(result);
+  }
+
+  return result;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: RenderEffects::safe_to_combine
 //       Access: Public

panda/src/pgraph/renderEffects.h

@@ -57,6 +57,7 @@ public:
   virtual ~RenderEffects();
 
   bool safe_to_transform() const;
+  virtual CPT(TransformState) prepare_flatten_transform(const TransformState *net_transform) const;
   bool safe_to_combine() const;
   CPT(RenderEffects) xform(const LMatrix4f &mat) const;
 

panda/src/pgraph/sceneGraphReducer.cxx

@@ -114,6 +114,7 @@ r_apply_attribs(PandaNode *node, const AccumulatedAttribs &attribs,
         << "Node " << *node
         << " contains a non-transformable effect; leaving transform here.\n";
     }
+    next_attribs._transform = effects->prepare_flatten_transform(next_attribs._transform);
     apply_types |= TT_transform;
   }
   if (!node->safe_to_transform()) {