Allow mesh and nodeboxes to wave like plants or leaves. (#3497)

We introduce a new value for "waving" - 2:

0 - waving disabled
1 - wave like a plant
2 - wave like a leave

Plantlike nodes will only allow waving = 1, but for leaves we will
permit both 1 and 2 since current minetest_game sets it to 1 for
all leaves. This makes it somewhat backwards compatible.

For mesh and nodebox, values 1 and 2 are both valid, and the node
can wave in both fashions as desired.

I've tested this with the crops:corn plants, which are mesh nodes,
and the results are really good. The code change is trivial as
well, so I've opted to document the waving parameter in lua_api.txt
because it was missing from there.

Nodeboxes likely will not wave properly unless waving = 2. However
it's possible that waving=1 may be desired by some mod developers
for geometries I have not tried, so the code will not prohibit
either value for mesh and nodebox drawtypes.

Add lua_api.txt documentation for this feature and document both
the existing functionality and the expansion to mesh and nodebox
drawtypes.

1 files changed, 6 insertions, 0 deletions

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index b47046cb1..603619ab0 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -3973,6 +3973,12 @@ Definition tables
         ^ If drawtype "nodebox" is used and selection_box is nil, then node_box is used. ]]
         legacy_facedir_simple = false, -- Support maps made in and before January 2012
         legacy_wallmounted = false, -- Support maps made in and before January 2012
+        waving = 0, --[[ valid for mesh, nodebox, plantlike, allfaces_optional nodes
+        ^ 1 - wave node like plants (top of node moves, bottom is fixed)
+        ^ 2 - wave node like leaves (whole node moves side-to-side synchronously)
+        ^ caveats: not all models will properly wave
+        ^ plantlike drawtype nodes can only wave like plants
+        ^ allfaces_optional drawtype nodes can only wave like leaves --]]
         sounds = {
             footstep = <SimpleSoundSpec>,
             dig = <SimpleSoundSpec>, -- "__group" = group-based sound (default)