In some corner cases the right-most / bottom-most vertex can be
right on the edge of the framebuffer. Because the maxx, maxy vals
are computed with a series of float/int, pixel/tile transformations
we can end up with maxx >= scene->x_tiles or maxy >= scene->y_tiles.
This leads to putting data into bins that never get processed, or
reset. This becomes stale data that can lead to segfaults.
Clamping fixes this.
The test to determine which of the pixels in a 2x2 quad is now done in
the fragment shader rather than in the calling C code. This is a little
faster but there's a few more things to do.
Note that the step[] array elements are in a different order now. Rather
than being in row-major order for the 4x4 grid, they're in "quad-major"
order. The setup of the step arrays is a little more complicated now.
So is the course/intermediate tile test code, but some lookup tables
help with that.
Next steps:
- early-cull 2x2 quads which are totally outside the triangle.
- skip the in/out test for fully contained quads
- make the in/out comparison code tighter/faster.
It was pretty confusing having an entity named "bin" and another named
"bins", not least because sometimes there was a need to talk about >1
of the "bins" objects, which couldn't be pluralized any further...
Scene is a term used in a bunch of places to talk about what a binner
operates on, so it's a decent choice here.
New lp_bins struct contains all bin information.
More move bin-related code into lp_bin.[ch]
Use new/updated bin-access functions to hide implementation details.
The result is more/cleaner separation between the setup and rast components.
This will make double-buffering of the bins easier, etc.
Previously, each triangle had a pointer to the state to use for shading.
Now we insert state-change commands into the bins. When we execute one
of those commands we just update a 'current state' pointer and use that
pointer when calling the jit shader.
When inserting state-change commands into a bin we check if the previous
command was also a state-change command and simply replace it. This
avoids accumulating useless/redundant state-change commands.
WIP, does't build or run.
Rasterizer code is based on Nick Capen's devmaster posts and the
larrabee articles, but currently doesn't share either the performance
or correctness of either...
Brian Paul
José Fonseca
Keith Whitwell