See #16847

It seems for front buffer pixel draws to show up
the OpenGL buffer has to be flushed.

This avoids forcing every library that includes a vtk header file to
link to tbb if vtk was built with this backend.

Changed ivar scope to protected as per VTK convention

ios has issues with GL_RGB and GL_BACK_LEFT

a279244d Add a display-coordinate offset to billboard text.
Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: T.J. Corona <tj.corona@kitware.com>
Merge-request: !2054

b7308935 Android: Remove unused toolchain file
982ba05a Android: Port superbuild to CMake 3.7 capabilities
971c3705 Android: Simplify superbuild compile tools target build
fc19439b Android: Require CMake 3.7 for superbuild
9c744b13 Android: Port build system to CMake 3.7 capabilities
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Ken Martin <ken.martin@kitware.com>
Merge-request: !2062

99607039 if msaa cannot find a working context disable it win32
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Berk Geveci <berk.geveci@kitware.com>
Merge-request: !2065

We no longer need the `android.toolchain.cmake` file because our Android
superbuild now configures using CMake 3.7's capabilities.

CMake 3.7 adds support for cross-compiling to Android without a complex
toolchain file.  Port our Android superbuild script to work without the
`android.toolchain.cmake` file.  Since CMake 3.7 now detects a lot of
information about the target platform up front we need to use a fresh
build tree for each API/ABI combination.

CMake 3.7 adds support for cross-compiling to Android without a complex
toolchain file.  Port our main CMake build system to work without the
`android.toolchain.cmake` file:

```
$ cmake ../VTK \
    -DCMAKE_SYSTEM_NAME=Android \
    -DCMAKE_ANDROID_NDK=/path/to/ndk \
    -DVTKCompileTools_DIR=/path/to/vtk-compile-tools \
    -DOPENGL_ES_VERSION=3.0 \
    -DVTK_Group_StandAlone=OFF
```

The old code would reduce the number of samples
requested but never disable it. This topic makes it
so that after reducing the number, if will if needed
try disabling MSAA altogether.

daea12d9 Fix a uninitalized memory in chart matrix
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Joachim Pouderoux <joachim.pouderoux@kitware.com>
Merge-request: !2061

048f89ab ifdef out valuepass code on ES2
Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !2060

his commit fix a valgrind detected memory bug
of uninitialized memory

ValuePass was having issues with OpenGL ES2 so
this topic ifdefs the code on that platform.  The result
is fairly messy so it really needs another pass at
some point to do it right. This is a quick fix as
we are heading to a release.

4284d9ed vtk_jsoncpp.h needs to define VTK_BUILD_SHARED_LIBS
Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: David E DeMarle <dave.demarle@kitware.com>
Merge-request: !2056

522e0bdd Change sample counter datatype to unsigned integer
8adca088 Minor documentation changes to reflect current implementation
4d5a1b4a Safely error out of fixed point mapper when using the average IP mode
d53eb241 Test for volume rendering with average intensity blend
94b2f0ca Compute scalar value in the volume scalar range space
0d22e4f4 GPU volume Mapper supports average intensity blend
3e49c8fc Shading done for composite blends only in volume rendering
d654b034 Add support for average blend in GPU volume mapper
...
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: David E DeMarle <dave.demarle@kitware.com>
Merge-request: !2026

ba43836c add option to draw lines as tubes
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Berk Geveci <berk.geveci@kitware.com>
Merge-request: !2050

2943135a Fixes build errors in ES 2.0.
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Ken Martin <ken.martin@kitware.com>
Merge-request: !2055

similar to the points as spheres this draws
lines as things that at least sort of look like
tubes.

This is used to set the dllimport macros and it cannot assume that
vtkConfigure.h is already included.

0ee7b639 a minor fix for windows lic_fix
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Berk Geveci <berk.geveci@kitware.com>
Merge-request: !2039

0455845f Add vtkBillboardTextActor3D.
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: T.J. Corona <tj.corona@kitware.com>
Merge-request: !2041

b0713d16 Rebuild graphics resources after releasing.
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: Ken Martin <ken.martin@kitware.com>
Merge-request: !2051

e554e0b6 Fix bug in vtkMapper::GetBounds.
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: T.J. Corona <tj.corona@kitware.com>
Merge-request: !2049

7ae0a995 Fixed memory leak when multiple time steps read from file
Acked-by: Kitware Robot <kwrobot@kitware.com>
Reviewed-by: T.J. Corona <tj.corona@kitware.com>
Merge-request: !2035

818d115e paraview handles picking a little differently
Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !2038

This fix handles the fact that PV initializes the
zbuffer prior to setting the selector on the
mappers during a pick.

This fixes the issue in paraview/paraview#16943.