Solved by adding RW lock to BKE_vfont_to_curve.
So now all the threads are allowed to read chars from ghash,
but they'll be locked as soon as one thread would need to load
more chars from font to the ghash.
This wasn't needed before now, but since recent change to bUnit_ReplaceString,
it uses in a context where NULL terminator is expected - best add.
(spotted by Sergey)
that cannot convert float to char without false warnings that are turned
into errors with strict flags. I expect that any real conversion
warnings can be caught on linux.
EWA sampling is designed for downsampling images, i.e. scaling down the size of
input image pixels, which happens regularly in compositing. While the standard
sampling methods (linear, cubic) work reasonably well for linear
transformations, they don't yield good results in non-linear cases like
perspective projection or arbitrary displacement. EWA sampling is comparable to
mipmapping, but avoids problems with discontinuities.
To work correctly the EWA algorithm needs partial derivatives of the mapping
functions which convert output pixel coordinates back into the input image
space (2x2 Jacobian matrix). With these derivatives the EWA algorithm
projects ellipses into the input space and accumulates colors over their
area. This calculation was not done correctly in the compositor, only the
derivatives du/dx and dv/dy were calculation, basically this means it only
worked for non-rotated input images.
The patch introduces full derivative calculations du/dx, du/dy, dv/dx, dv/dy for
the 3 nodes which use EWA sampling currently: PlaneTrackWarp, MapUV and
Displace. In addition the calculation of ellipsis area and axis-aligned
bounding boxes has been fixed.
For the MapUV and Displace nodes the derivatives have to be estimated by
evaluating the UV/displacement inputs with 1-pixel offsets, which can still have
problems on discontinuities and sub-pixel variations. These potential problems
can only be alleviated by more radical design changes in the compositor
functions, which are out of scope for now. Basically the values passed to the
UV/Displacement inputs would need to be associated with their 1st order
derivatives, which requires a general approach to derivatives in all nodes.
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.
Simple/predictable polygon filling functions (no hole support)
originally from libgdx which have some advantages over scanfill.
- always creates the same number of triangles (never any missing faces).
- gives same results for any affine transformation.
- doesn't give so many skinny faces by default.
made some changes for Blender.
- remove last ears first (less to memmove)
- step over the ears while clipping to avoid some verts becoming fans to most of the other.
