The title says it all, move the EWA filter to BLI (currently it's
math_interp.c) and use the function from both BI renderer and the
compositor.
This makes more central place of the algorithm, allowing to have
fixes and optimizaitons synchronized across the two usages.
This also fixes T41440: Displacement in compositing creates holes
Reviewers: campbellbarton, lukastoenne
Reviewed By: lukastoenne
Maniphest Tasks: T41440
Differential Revision: https://developer.blender.org/D748
inputs.
http://wiki.blender.org/uploads/4/4c/Compo_image_interpolation_borders.png
Problem is that all image buffer reader nodes (RenderLayer, Image,
MovieClip) were clipping pixel coordinates to 0..N range (N being width
or height respectively). Bilinear interpolation works ok then on the
upper-right borders (x, N) and (N, y), since the last (N-1) pixel fades
out to N (background). But the lower-left (x, 0) and (0, y) borders are
not correctly interpolated because the nodes cut off the negative pixels
before the interpolation function can calculate their value.
To fix this, the interpolation functions are now entirely responsible
for handling "out of range" cases, i.e. setting (0,0,0,0) results for
invalid pixels, while also handling interpolation for borders.
Callers should not do pixel range checks themselves, which also makes
the code simpler. Should not have any real performance penalty,
the interpolation functions do this check anyway, so is probably even
slightly faster.
Couple of precision issues here:
- Interpolation was rounding trunkcating colors, and because
of some precision issues value 254.999 became 254 leading
to troubles later.
Now color interpolaiton will do rounding to nearest int.
- Subtract was setting channels to something negative which
confused color management (especially negative alpha),
Now subtract effect will clamp channels to 0 from bottom
and also do some tricks to prevent small alpha which
could also confuse color management.
Originally issue was discovered when using stabilization and movie distortion
nodes, but in fact issue was caused by render layer node always doing nearest
interpolation. Now made it so this node will respect sampler passed to it's
executePixel function and do an interpolation.
Added two new functions to do bilinear/bicubic interpolation in float buffer
with variable number of components per element, so it could interpolate 1, 3
and 4 component vectors. This functions currently mostly duplicates the same
functions from imageprocess.c and it should actually be de-duplicated. Think
it's ok to leave a bit of time with such duplication, since functions should
be generalized one more time to support byte buffers, which could backfire on
readability.
Also removed mark as complex from stabilization node, which isn't needed sine
int fact this node is not complex.
