Decoration API: Add lightweight ability to have complete coverage (#7456)

When the noise value or fill_ratio >= 10.0 complete coverage is enabled.
This disables random placement to avoid redundant multiple placements
at one position. Instead, 1 decoration per surface node is placed by
looping across each division.

'10' was chosen as this is the fill_ratio that previously created
very near complete coverage. The complete coverage feature therefore
integrates smoothly when noise is used for variable decoration density.

'fill_ratio = 10' should be used by modders who want a decoration
placed on every surface node. Compared to before such a decoration
placement will be 10 times faster.

1 files changed, 4 insertions, 0 deletions

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index db340e415..743cca47d 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -5769,6 +5769,8 @@ Definition tables
         fill_ratio = 0.02,
     --  ^ The value determines 'decorations per surface node'.
     --  ^ Used only if noise_params is not specified.
+    --  ^ If >= 10.0 complete coverage is enabled and decoration placement uses
+    --  ^ a different and much faster method.
         noise_params = {
             offset = 0,
             scale = 0.45,
@@ -5783,6 +5785,8 @@ Definition tables
     --  ^ distribution.
     --  ^ A noise value is calculated for each square division and determines
     --  ^ 'decorations per surface node' within each division.
+    --  ^ If the noise value >= 10.0 complete coverage is enabled and decoration
+    --  ^ placement uses a different and much faster method.
         biomes = {"Oceanside", "Hills", "Plains"},
     --  ^ List of biomes in which this decoration occurs. Occurs in all biomes
     --  ^ if this is omitted, and ignored if the Mapgen being used does not