Warn about negative scales

 * Get the Projector earlier
 * Cleanup the workspace if the rendering fails
 * Add a warning if the objects has negative scale values, blender does
   not transform normals correctly in this case

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>

diff --git a/vrm.py b/vrm.py
index aa73b10..35df00c 100755 (executable)
--- a/vrm.py
+++ b/vrm.py
@@ -57,7 +57,9 @@ __bpydoc__ = """\
 #     Think to a way to merge adjacent polygons that have the same color.
 #     Or a way to use paths for silhouettes and contours.
 #   - Add Vector Writers other that SVG.
-#   - Consider SMIL for animation handling instead of ECMA Script?
+#   - Consider SMIL for animation handling instead of ECMA Script? (Firefox do
+#     not support SMIL for animations)
+#   - FIX the issue with negative scales in object tranformations!
 #
 # ---------------------------------------------------------------------
 #
@@ -408,6 +410,7 @@ class SVGVectorWriter(VectorWriter):
         self.file.write("<g id=\"frame%d\" style=\"%s\">\n" %
                 (framenumber, framestyle) )
 
+
         for obj in Objects:
 
             if(obj.getType() != 'Mesh'):
@@ -575,8 +578,6 @@ class SVGVectorWriter(VectorWriter):
             
             hidden_stroke_style = ""
             
-            # We consider an edge visible if _both_ its vertices are selected,
-            # hence an edge is hidden if _any_ of its vertices is deselected.
             if e.sel == 0:
                 if showHiddenEdges == False:
                     continue
@@ -647,6 +648,12 @@ class Renderer:
         # Render from the currently active camera 
         self.cameraObj = self._SCENE.getCurrentCamera()
 
+        # Get a projector for this camera.
+        # NOTE: the projector wants object in world coordinates,
+        # so we should remember to apply modelview transformations
+        # _before_ we do projection transformations.
+        self.proj = Projector(self.cameraObj, self.canvasRatio)
+
         # Get the list of lighting sources
         obj_lst = self._SCENE.getChildren()
         self.lights = [ o for o in obj_lst if o.getType() == 'Lamp']
@@ -692,7 +699,16 @@ class Renderer:
         for f in range(startFrame, endFrame+1):
             context.currentFrame(f)
 
-            renderedScene = self.doRenderScene(self._SCENE)
+            # Use some temporary workspace, a full copy of the scene
+            inputScene = self._SCENE.copy(2)
+            
+            try:
+                renderedScene = self.doRenderScene(inputScene)
+            except:
+                self._SCENE.makeCurrent()
+                Scene.unlink(inputScene)
+                del inputScene
+
             outputWriter.printCanvas(renderedScene,
                     doPrintPolygons = PRINT_POLYGONS,
                     doPrintEdges    = PRINT_EDGES,
@@ -708,22 +724,13 @@ class Renderer:
         context.currentFrame(currentFrame)
 
 
-    def doRenderScene(self, inputScene):
+    def doRenderScene(self, workScene):
         """Control the rendering process.
         
         Here we control the entire rendering process invoking the operation
         needed to transform and project the 3D scene in two dimensions.
         """
         
-        # Use some temporary workspace, a full copy of the scene
-        workScene = inputScene.copy(2)
-
-        # Get a projector for this scene.
-        # NOTE: the projector wants object in world coordinates,
-        # so we should apply modelview transformations _before_
-        # projection transformations
-        proj = Projector(self.cameraObj, self.canvasRatio)
-
         # global processing of the scene
 
         self._doConvertGeometricObjToMesh(workScene)
@@ -773,7 +780,7 @@ class Renderer:
 
             self._doEdgesStyle(mesh, edgeSelectionStyles[EDGE_STYLE])
 
-            self._doProjection(mesh, proj)
+            self._doProjection(mesh, self.proj)
             
             # Update the object data, important! :)
             mesh.update()
@@ -932,11 +939,17 @@ class Renderer:
     def _joinMeshObjectsInScene(self, scene):
         """Merge all the Mesh Objects in a scene into a single Mesh Object.
         """
+
+        oList = [o for o in scene.getChildren() if o.getType()=='Mesh']
+
+        # FIXME: Object.join() do not work if the list contains 1 object
+        if len(oList) == 1:
+            return
+
         mesh = Mesh.New()
         bigObj = Object.New('Mesh', 'BigOne')
         bigObj.link(mesh)
 
-        oList = [o for o in scene.getChildren() if o.getType()=='Mesh']
         bigObj.join(oList)
         scene.link(bigObj)
         for o in oList:
@@ -971,6 +984,11 @@ class Renderer:
         This step is done simply applying to the object its tranformation
         matrix and recalculating its normals.
         """
+        # XXX FIXME: blender do not transform normals in the right way when
+        # there are negative scale values
+        if matrix[0][0] < 0 or matrix[1][1] < 0 or matrix[2][2] < 0:
+            print "WARNING: Negative scales, expect incorrect results!"
+
         mesh.transform(matrix, True)
 
     def _doObjectDepthSorting(self, mesh):
@@ -1137,10 +1155,9 @@ class Renderer:
 
         for e in mesh.edges:
 
+            e.sel = 0
             if edgestyleSelect(e, mesh):
                 e.sel = 1
-            else:
-                e.sel = 0
                 
     def _doProjection(self, mesh, projector):
         """Calculate the Projection for the object.