As described in #62, the non-deterministic scene monoid may result in
slightly different transformations for path segments in an otherwise
closed path.
This change ensures consistent transformation across paths in three steps.
First, absolute transformations computed by the scene monoid is stored
along with path segments and annotated elements.
Second, elements.comp no longer transforms path segments. Instead, each
segment is stored untransformed along with a reference to its absolute
transformation.
Finally, path_coarse performs the transformation of path segments.
Because all segments in a path share a single transformation reference,
the inconsistency in #62 is avoided.
Fixes#62
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Defining MEM_DEBUG in mem.h will add a size field to Alloc and enable
bounds and alignment checks for every memory read and write.
Notes:
- Deriving an Alloc from Path.tiles is unsound, but it's more trouble to
convert Path.tiles from TileRef to a variable sized Alloc.
- elements.comp note that "We should be able to use an array of structs but the
NV shader compiler doesn't seem to like it". If that's still relevant, does
the shared arrays of Allocs work?
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The binning shader supports up to N_TILE bins. To efficiently cover wide or
tall viewports, convert the rigid N_TILE_X x N_TILE_Y bin layout to a variable
width_in_bins x height_in_bins layout.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Merge all static and dynamic buffers to just one, "memory". Add a malloc
function for dynamic allocations.
Unify static allocation offsets into a "config" buffer containing scene setup
(number of paths, number of path segments), as well as the memory offsets of
the static allocations.
Finally, set an overflow flag when an allocation fail, and make sure to exit
shader execution as soon as that triggers. Add checks before beginning
execution in case the client wants to run two or more shaders before checking
the flag.
The "state" buffer is left alone because it needs zero'ing and because it is
accessed with the "volatile" keyword.
Fixes#40
Signed-off-by: Elias Naur <mail@eliasnaur.com>
I realized there's a problem with encoding clip bboxes relative to the
current transform (see #36 for a more detailed explanation), so this is
changing it to absolute bboxes.
This more or less gets clips working. There are optimization
opportunities (all-clear and all-opaque mask tiles), and it doesn't deal
with overflow of the blend stack, but it seems to basically work.
Actually handle transforms in RenderCtx (was implemented in renderer but
not actually plumbed through). This also requires maintaining a state
stack, which will also be required for clipping.
This PR also starts work on encoding clipping, including tracking
bounding boxes.
WIP, none of this is tested yet.
Expand the the final kernel4 stage to maintain a per-pixel mask.
Introduce two new path elements, FillMask and FillMaskInv, to fill
the mask. FillMask acts like Fill, while FillMaskInv fills the area
outside the path.
SVG clipPaths is then representable by a FillMaskInv(0.0) for every nested
path, preceded by a FillMask(1.0) to clear the mask.
The bounding box for FillMaskInv elements is the entire screen; tightening of
the bounding box is left for future work. Note that a fullscreen bounding
box is not hopelessly inefficient because completely filling a tile with
a mask is just a single CmdSolidMask per tile.
Fixes#30
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Path segments are unsorted, but other elements are using the same
sort-middle approach as before.
This is a checkpoint. At this point, there are unoptimized versions
of tile init and coarse path raster, but it isn't wired up into a
working pipeline. Also observing about a 3x performance regression in
element processing, which needs to be investigated.
Trying to fit it into the fancy monad doesn't really work, so use a
more straightforward approach to compute it from the aggregate.
Also add yEdge logic (basically copying piet-metal). With a fix to
ELEMENT_BINNING_RATIO (which I had simply gotten wrong), the example
renders almost correctly, with small bounding box artifacts.
Write the right_edge to the binning output.
More work on encoding the fill/stroke distinction and plumbing that
through the pipeline. This is a bit unsatisfying because of the code
duplication; having an extra fill/stroke bool might be better, but I
want to avoid making the structs bigger (this could be solved by
better packing in the struct encoding).
Fills are plumbed through to the last stage. Backdrop is WIP.
This should get the "right_edge" value for each segment plumbed through
to the binning phase. It also needs to be plumbed to coarse raster and
wired up there.
Also considering WIP because none of this logic has been tested yet.
