D3D12: Fix 'ShaderEffect in a ShaderEffectSource as property value'

Import (and clean up) the dropshadow from the shadereffects example.
This is very useful since it tests a lot more paths and cases than
the wobble.

To overcome the issue of not having some of functionality available before
the item is added to a window, make QQuickGenericShaderEffect smarter and
enhance the documentation.

The handling of vertical mirroring is revised. The GLSL and HLSL version of
the dropshadow shaders produce correct, identical output now.

Change-Id: I94800997bfba781140d80720eb6f340cda480747
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 0 insertions, 0 deletions

diff --git a/tests/manual/nodetypes/ps_shadow2.cso b/tests/manual/nodetypes/ps_shadow2.cso
new file mode 100644
index 0000000000..ab8cb63f34
--- /dev/null
+++ b/tests/manual/nodetypes/ps_shadow2.cso