Horizon mapping is a method of shadow mapping specific to height maps.
It can handle any angle between 0 and 90 degrees from the ground, as
long as know the horizontal direction in advance, by remembering only a
single angle (the "horizon angle" of the shadow map). More is explained
in common/src/msg/server.rs. We also remember the approximate height of
the largest occluder, to try to be able to generate soft shadows and
create a vertical position where the shadows can't go higher.
Additionally, map generation has been reworked. Instead of computing
everything from explicit samples, we pass in sampling functions that
return exactly what the map generator needs. This allows us to cleanly
separate the way we sample things like altitudes and colors from the map
generation process. We exploit this to generate maps *partially* on the
server (with colors and rivers, but not shading). We can then send the
partially completed map to the client, which can combine it with shadow
information to generate the final map. This is useful for two reasons:
first, it makes sure the client can apply shadow information by itself,
and second, it lets us pass the unshaded map for use with level of
detail functionality.
For similar reasons, river generation is split
out into its own layer, but for now we opt to still generate rivers on
the server (since the river wire format is more complicated to compress
and may require some extra work to make sure we have enough precision to
draw rivers well enough for LoD).
Finally, the mostly ad-hoc lighting we were performing has been (mostly)
replaced with explicit Phong reflection shading (including specular
highlights). Regularizing this seems useful and helps clarify the
"meaning" of the various light intensities, and helps us keep a more
physically plausible basis. However, its interaction with soft shadows
is still imperfect, and it's not yet clear to me what we need to do to
turn this into something useful for LoD.
Currently it just always rotates towards the camera, but it wouldn't be
hard to create a config option that swaps out the rotation of the
indicator and the map.
With these changes, we can successfully open, map, and play maps thare
are 16x the size of a standard (1024 x 1024 chunk) map, 4x larger in
each direction.
Turned a lot of for loops into for_each loops, which should be easier
for LLVM to optimize currently. Also updated almost all the non-erosion
stuff in WorldGen to run in parallel (and take advantage of the cache,
in the case of TownGen), and hopefully improved performance somewhat for
chunk generation as well.
- soil production (currently disabled).
- debris flow erosion (combined with regular stream power law).
- flow computation using multiple receivers.
- filling strategy during drainage network calculations.
Also tweaks a variety of other aspects of erosion.
Currently we only do this when no players are in range of the chunk. We
also send the first client who posted the chunk a message indicating
that it's canceled, the hope being that this will be a performance win
in single player mode since you don't have to wait three seconds to
realize that the server won't generate the chunk for you.
We now check an atomic flag for every column sample in a chunk. We
could probably do this less frequently, but since it's a relaxed load it
has essentially no performance impact on Intel architectures.
See the doc comments in `common/src/vol.rs` for more information on
the API itself.
The changes include:
* Consistent `Err`/`Error` naming.
* Types are named `...Error`.
* `enum` variants are named `...Err`.
* Rename `VolMap{2d, 3d}` -> `VolGrid{2d, 3d}`. This is in preparation
to an upcoming change where a “map” in the game related sense will
be added.
* Add volume iterators. There are two types of them:
* _Position_ iterators obtained from the trait `IntoPosIterator`
using the method
`fn pos_iter(self, lower_bound: Vec3<i32>, upper_bound: Vec3<i32>) -> ...`
which returns an iterator over `Vec3<i32>`.
* _Volume_ iterators obtained from the trait `IntoVolIterator`
using the method
`fn vol_iter(self, lower_bound: Vec3<i32>, upper_bound: Vec3<i32>) -> ...`
which returns an iterator over `(Vec3<i32>, &Self::Vox)`.
Those traits will usually be implemented by references to volume
types (i.e. `impl IntoVolIterator<'a> for &'a T` where `T` is some
type which usually implements several volume traits, such as `Chunk`).
* _Position_ iterators iterate over the positions valid for that
volume.
* _Volume_ iterators do the same but return not only the position
but also the voxel at that position, in each iteration.
* Introduce trait `RectSizedVol` for the use case which we have with
`Chonk`: A `Chonk` is sized only in x and y direction.
* Introduce traits `RasterableVol`, `RectRasterableVol`
* `RasterableVol` represents a volume that is compile-time sized and has
its lower bound at `(0, 0, 0)`. The name `RasterableVol` was chosen
because such a volume can be used with `VolGrid3d`.
* `RectRasterableVol` represents a volume that is compile-time sized at
least in x and y direction and has its lower bound at `(0, 0, z)`.
There's no requirement on he lower bound or size in z direction.
The name `RectRasterableVol` was chosen because such a volume can be
used with `VolGrid2d`.
Humidity and temperature are now indexed to uniform altitude *over land
chunks* (and water chunks adjacent to land) rather than over the whole
range of altitude. This is necessary in order to satisfy the uniformity
conditions of the formula for weighted sum CDF.
Additionally, fixes the computation of whether a tree should be
generated or not. Previously, it was using a source of randomness
scaled to use much less than the full 0-1 range; this has been resolved.
This makes for much nicer and more gradual transitions between densities
and reduces the amount of completely barren landscapes, while also
making forests larger.
Finally, this commit adds a server command, debug_column, which returns
some useful debug information about a column given an x and y
coordinate. This is useful for debugging worldgen.
Also fix some things to use a consistent coordinate system and bump up
tree density and variation around tree density in hopes of creating more
aesthetically pleasing jungles. However, this does change worldgen a
bit, so please make sure you look through it before merging.
