Parts

Parts are Roblox parts that spawn throughout the map. They can be picked up, welded, and cut by players. Parts come in a variety of colors, shapes and sizes. They are one of the core building materials of the game, the other being items.

Spawning

Upon server start, 4,800 parts are spawned around the map. Each part has a random position, size, material, shape and color. For positioning, the map has designated spawn areas for parts and items. An algorithm picks between these areas, giving each one a probability equal to its volume, then calculates a random position and rotation within the area. For shape, each part has a ~60% chance of being a block and a ~40% chance of being a cylinder.

Materials

For material, one is picked according to the probability table below.

Material	Chance	Value
CorrodedMetal	30.6%	0.8
Metal	19.6%	1
SmoothPlastic	19.6%	1
DiamondPlate	13.6%	1.2
Glass	13.6%	1.2
Foil	3.1%	2.5

Below is the code used to calculate that table, which can be run by any injector such as Synapse or Script-Ware. The reason for the (1 / v) ^ 2 formula is that the part spawning script uses that formula when choosing which material to pick. (confirmed by the developer)

local valuebook = require(game.ReplicatedStorage.ValueBook)

local total = 0
for _, v in pairs(valuebook.MaterialValues) do
	total += (1 / v) ^ 2
end

for _, v in pairs(valuebook.Materials) do
	local value = (1 / valuebook.MaterialValues[v])^2
	print(v, tostring((value / total) * 100) .. '%', value)
end

Sizing

For size, the value of the picked material is used as a bias. The bias skews the random distribution such that higher bias values cause lower random numbers to be more common. In practice this means that parts with rarer materials tend to spawn smaller, but all sizes are still possible. Then, the Y and Z values are randomly generated. Each component is calculated as math.random()^bias * 9 + 1, which means a random number from 1 to 10, skewed by the bias. Again, higher biases (such as foil's bias of 2.5) mean that the size will tend towards the 1, while lower biases (such as in the case of corroded metal) tend to skew towards 10.

The maximum value for the X component will be a value N such that Y * Z * N == 125. In order words the maximum volume of the part will be 125 studs squared. The minimum value of the X component is always 0.2. Then a random number is generated between those two values, skewed by the bias once again.

The full function is thusly:

function Part:RandomSize(bias)
	local y = math.random()^bias * 9 + 1
	local z = math.random()^bias * 9 + 1
	local x = math.min(math.random()^bias * (125 / (y * z) - 0.2) + 0.2, 10)
	
	return Vector3.new(x, y, z)
end

Colors

Parts mainly spawn in dull and muted tones, with some greys and whites mixed in. Rather than a list of BrickColors, part colors are generated as Color3 values, so there is an entire spectrum of possible colors. Nonetheless, the spectrum is limited and is only a small fraction of the color space. Here is a graph showing the entire part color spectrum (click on it for a larger version):

On the left is the hue and lightness spectrum, and on the right is the saturation spectrum. The range of saturation values for a color depends on its lightness, which is why there is a separate saturation graph next to the main one. To pick a color from the spectrum, first the game chooses the hue and lightness from the graph on the left, and then it chooses a saturation from the graph on the right. As you can see, brighter colors have a smaller saturation range.

The color generation code is as follows:

local hue = math.random()
local lightness = rand(0.1, 1, 0.75)
local saturation = rand(0.1, 0.5 - (lightness^0.5 * 0.4), 5)

rand(min, max, bias) generates a random number between its two first arguments, biased by the third argument. Notice that lightnesses below 0.1 are impossible to spawn and so are saturations below 0.1, which are both reflected in the graph.

BrickColors found in-game

Color Name	Spawnrate	Rgb
Black	Very High	*
Insitutional white	Very High	*
Mid grey	Very High	*
Cloudy grey	High	*
Dark grey	High	*
Dark taupe	High	*
Dirt brown	High	*
Earth green	High	*
Fossil	High	*
Ghost grey	High	*
Grey	High	*
Hurricane grey	High	*
Pearl	High	*
Light grey	High	*
Light stone grey	High	*
Quill grey	High	*
Sand green	High	*
Sand red	High	*
Sand violet	High	*
Sage green	High	*
Smoky grey	High	*
White	High	*
Artichoke	Medium	*
Cadet blue	Medium	*
Dark stone grey	Medium	*
Earth blue	Medium	*
Faded green	Medium	*
Flint	Medium	*
Grime	Medium	*
Lily white	Medium	*
Linen	Medium	*
Medium stone grey	Medium	*
Oyster	Medium	*
Pine Cone	Medium	*
Really Black	Medium	*
Sand blue	Medium	*
Sand yellow	Medium	*
Silver	Medium	*
Slime green	Medium	*
Brown	Low	*
Cocoa	Low	*
Copper	Low	*
Earth yellow	Low	*
Fog	Low	*
Moss	Low	*
Mulberry	Low	*
Laurel green	Low	*
Reddish lilac	Low	*
Bright bluish violet	Very Low	*
Bright reddish lilac	Very Low	*
Bright violet	Very Low	*
Bronze	Very Low	*
Lavender	Very Low	*
Lilac	Very Low	*
Medium bluish violet	Very Low	*
Medium lilac	Very Low	*
Plum	Very Low	*
Seashell	Very Low	*
Steel blue	Very Low	*
Storm blue	Very Low	*
Tawny	Very Low	*
Beige	Extremely Low	*
Bright green	Extremely Low	*
Bright reddish violet	Extremely low	*
Burlap	Extremely Low	*
Burgundy	Extremely Low	*
Dark green	Extremely Low	*
Earth orange	Extremely Low	*
Fawn brown	Extremely Low	*
Light bluish green	Extremely Low	*
Light lilac	Extremely Low	*
Med. reddish violet	Extremely Low	*
Medium green	Extremely Low	*
Olivine	Extremely Low	*
Parsley Green	Extremely Low	*
Reddish brown	Extremely Low	*
Daisy orange	Almost impossible	*
Royal Blue	Almost impossible	*
Turquoise	Almost impossible	*

Debug Colors

Older versions of Grassy Landscape spawned random BrickColors instead of using a color spectrum. Colors outside the spawnable spectrum are referred to as "debug colors", since they used an unfinished algorithm for debugging purposes (i.e. to get the rest of the game working first). Since there is currently no save system, and all debug colors have been removed from the game, it is no longer possible to encounter a part color outside of the spectrum.

"Rare BrickColors"

When generating colors, the game will refuse to generate any color that happens to be a "rare BrickColor". The list of rare BrickColors is below:

Name	Reason
Lig. Yellowich orange	Typo
Light green (mint)	Parenthesis
Phosph. White	Cool name
Transparent	Transparent
Tr. Red	Transparent
Tr. Lg blue	Transparent
Tr. Blue	Transparent
Tr. Yellow	Transparent
Tr. Flu. Reddish orange	Transparent
Tr. Green	Transparent
Tr. Flu. Green	Transparent
Tr. Brown	Transparent
Tr. Medi. reddish violet	Transparent
Tr. Bright bluish violet	Transparent
Tr. Flu. Blue	Transparent
Tr. Flu. Yellow	Transparent
Tr. Flu. Red	Transparent
Red flip/flop	Flip/flop
Yellow flip/flop	Flip/flop
Silver flip/flop	Flip/flop
Sand blue metallic	Metallic
Sand violet metallic	Metallic
Sand yellow metallic	Metallic
Dark grey metallic	Metallic
Black metallic	Metallic
Light grey metallic	Metallic
Gun metallic	Metallic
Lemon metalic	Bkerr's favorite color

If the algorithm generates a color that is "rare", it will simply re-roll until it lands on one that isn't. Most likely, if someone has a part with one of these colors, it was obtained from an event or someone with the debug GUI.