sw_engine shape: improvement of the rectangle fast tracking algorithm #126
Conversation
src/lib/sw_engine/tvgSwShape.cpp
Outdated
| auto min1 = pt1->y < pt3->y ? pt1 : pt3; | ||
| auto min2 = pt2->y < pt4->y ? pt2 : pt4; | ||
| if (min1->y != min2->y) return false; | ||
| if (*pt1 == *pt4 && *pt2 == *pt3) return false; |
There was a problem hiding this comment.
Is this condition necessary?
I think, In tvgSwShape's updateBBox, width and height are already being checked.
I think fastTrack only needs to check if it is rectangle.
There was a problem hiding this comment.
this condition prevents from filling the whole bbox when the rect has a zero width.
Since the pictures in the Stress example were so small, the zero width rect occured sometimes and that was the reason why we saw 'the flashes'.
There was a problem hiding this comment.
I misspelled 'zero width rect' when I meant 'zero width parallelogram' - there are, of course, parallelograms on the pictures in the description.
I also found an issue in my previous solution, so I decided to completely change the algorithm.
Please have a look now.
The algorithm erroneously treated some shapes (like isosceles trapezoids and specifically arranged zero width parallelograms) as rectangles, which causes the whole bbox to be filled.
mgrudzinska
force-pushed
the
mgrudzinska/Stress_fixed
branch
from
56016ec
to
545a886
Compare
Description :
The algorithm erroneously treated some shapes (like isosceles trapezoids and specifically arranged zero width parallelograms) as rectangles, witch causes the whole bbox to be filled - undesirable behavior.
Issue Tickets (if any) : Rendering is graphically broken #77
Tests or Samples (if any) :
a) Stress.cpp from examples
b) Svg.cpp for the image errorsStress.svg:
https://github.com/mgrudzinska/thorvg/tree/mgrudzinska/Stress_ex_error
Screen Shots (if any) :
errorsStress.svg:
Before (wrong):
After (correct):
