MantisBT - VTK
http://vtk.1045678.n5.nabble.com/Toggling-ScalarVisibility-ruins-actor-s-backface-color-td5714065.html [^]
Here is a hard-copy of it:
Hi everyone
assume that you have a scene with one actor having different front and backface color.
Frontface color: RED RGB(1,0,0)
Backface color: BLUE RGB(0,0,1)
During the 1st rendering of course they will look like as specified. Check the attached first two images.
(step1-frontface-red-OK.png, step2-backface-blue-OK.png)
When I turn on vtkPolyDataMapper's ScalarVisibility the rainbow scalars are also looks fine. Check the attached third image, step3-scalar-mapping-OK.png
However when i turn off the ScalarVisibility again (like it was the case for the initial step) the previously defined blue actor backface color become red, step4-backface-become-red-NOTOK.png
What is even more strange is that from that point changing the actor's backface color is not possible!
Also any change on the frontface color applies now as backface color as well :(
I faced this issue in our C++ project first. For this forum topic I built a TCL demo of my own to reproducate the problem.
(That TCL is based on the well-known VTK example located at \Examples\Rendering\Tcl\rainbow.tcl)
How to reproducate:
During rendering you can issue user commands by pressing 'u' key. On that window you can do
- set the scalar visibility to on or off by entering the following tcl commands
planeMapper ScalarVisibilityOff
planeMapper ScalarVisibilityOn
- change the front or backface color
eval [planeActor GetProperty] SetColor 1.0 0.0 0.0
backProp SetColor 0.0 0.0 1.0
Can you spot why it happened?
The problems comes by using VTK 5.8.0 on WinXP 32bit and on different 64 bit Linux machine too.
regards,
Peter
Check the attachments!
Jochen K. found the followings:
===============================
The only thing I found out so far is the function which is rendering the backface
(look at function vtkActor::RenderOpaqueGeometry(vtkViewport *vp) for this call: this->BackfaceProperty->BackfaceRender(this, ren))
is called (having backProp color set to Blue) no matter how ScalarVisibility is set, which indeed is surprising me.
After this->BackfaceProperty->BackfaceRender(this, ren) has been called
another two calls are made:
this->Render(ren,this->Mapper); // which calls the superclass Render function
this->Property->PostRender(this, ren);
The "failure" seems to be located within one of these two functions but I cannot find it.
I have the feeling that this issue should be escalated to the developer crew. I'm running out of any idea.
attachment.zip (72,707) 2012-06-22 08:50https://www.vtk.org/Bug/file/9216/attachment.zip