This should improve cache coherency by having all surface tiles adjacent
instead of strewn across the heap. This will also remove an indirection
in the common case of only using one tile.
With this change, an additional rectangle is stored in C4FoWRegion that
represents the area covered by the viewport in fractional floating point
coordinates. This allows the light texture to be created for an arbitrary
portion of the landscape, and the coordinate transformations for the
shaders will still work.
Also, since the additional rectangle uses floating point precision, the
computed coordinate transformations do now give the exact same result as for
the landscape pixel-by-pixel, and there should not be any offsets left.
I also hope that this change improves or fixes the single-pixel-lines of sky
that are sometimes seen at the edges of the viewport.
There were two problems with the previous transforms:
1) For inverting the Y axis for the ambient map, the total height of the
output window is needed, not only the viewport region.
2) The Y offset to only use the part of the light texture that is being
rendered to was not applied.
In order to keep the transformations more readable, a new lightweight class
C4FragTransform has been introduced which can only handle translations
and scales in x and y.
Now we use the shader to do a proper blend - this avoids some artefacts
that were visible before. Also after some hair-pulling the coordinate
transformation now seems to be more correct than before. Maybe even
with zoom. We'll see.
* added some class and method documentation, removed some superfluous comments like
void C4FoW::Update(C4Rect r)
{
// Update all lights
...
* added ASK comments that need clarification before proper documentation
Peter Wortmann