Greedy mesher

Greedymeshing.lua

--[[
	
Performs greedy meshing on custom Voxel blocks

made by Megustral

]]

local RunService = game:GetService("RunService")

local Settings = require(script.Parent.Settings)
local Size = Vector3.new(1, 1, 1)

return function (Chunk)
	
	local PartInstructions = {}
	local IsMeshed = {}
	
	for y = 1, Settings.ChunkSize.Y do
		for z = 1, Settings.ChunkSize.Z do
			for x = 1, Settings.ChunkSize.X do
				
				-- Perform GreedyMeshing
				local PositionStartingPart = Vector3.new(x, y, z)
				
				-- Check if the part is already meshed
				if IsMeshed[PositionStartingPart] then continue end
				
				local Voxel = Chunk[PositionStartingPart]
				
				-- If there is no voxel why bother
				if not Voxel then continue end
				
				-- A instruction that will be used for the renderer
				local Part = {
					Position = PositionStartingPart,
					Size = Size,
					Voxel = Voxel
				}
				
				-- Performs the greedy meshing
				do
					-- basically how it works:
					-- we check the part next to it, if its valid, we increase the size and tell the system that that part is meshed
					-- we do this on the x axis, but when we do it on the z axis its kinda different
					-- we first go through every block on the x axis one stud farther from the z
					-- if one of them is not the same and is air, cancel the operation
					-- and break the loop. if it doesnt fail, we increase the size of the part
					-- then we do that also for the y axis but check both z and x
					
					for greedX = x+1, Settings.ChunkSize.X do
						
						-- Check if the voxels are the same
						local PositionMeshedPart = Vector3.new(greedX, y, z)
						local VoxelMeshed = Chunk[PositionMeshedPart]
						
						if Voxel == VoxelMeshed then
							
							Part.Size += Vector3.new(1, 0, 0)
							Part.Position += Vector3.new(0.5, 0, 0)
							
							IsMeshed[PositionMeshedPart] = true
							
						else
							
							break
							
						end
						
					end
					
					for greedZ = z+1, Settings.ChunkSize.Z do
						
						local IsSame = true
						
						for greedX = x, Part.Size.X do
							
							local PositionMeshedPart = Vector3.new(greedX, y, greedZ)
							local VoxelMeshed = Chunk[PositionMeshedPart]
							
							if Voxel ~= VoxelMeshed then
								
								IsSame = false
								break
								
							end
							
						end
						
						if not IsSame then break end
						
						Part.Size += Vector3.new(0, 0, 1)
						Part.Position += Vector3.new(0, 0, 0.5)
						
						for greedX = x, Part.Size.X do
							
							local PositionMeshedPart = Vector3.new(greedX, y, greedZ)
							IsMeshed[PositionMeshedPart] = true
							
						end 
						
					end
					
					for greedY = y+1, Settings.ChunkSize.Y do
						
						local IsSame = true
						
						for greedZ = z, Part.Size.Z do
							
							local IsSameZ = true
							
							for greedX = x, Part.Size.X do
								
								local PositionMeshedPart = Vector3.new(greedX, greedY, greedZ)
								local VoxelMeshed = Chunk[PositionMeshedPart]
								
								if Voxel ~= VoxelMeshed then
									IsSameZ = false
									break
								end
								
							end
							
							-- Breaks the greedy meshing operation
							if not IsSameZ then
								IsSame = false
								break
							end
							
						end
						
						if IsSame then
							
							Part.Size += Vector3.new(0, 1, 0)
							Part.Position += Vector3.new(0, 0.5, 0)
							
							-- Mark all these parts as greedy meshed
							for greedZ = z, Part.Size.Z do
								for greedX = x, Part.Size.X do
									
									local PositionMeshedPart = Vector3.new(greedX, greedY, greedZ)
									IsMeshed[PositionMeshedPart] = true
									
								end
							end
							
						end
						
					end
				end
				--Part.Position += Chunk.Position * Settings.ChunkSize
				table.insert(PartInstructions, Part)
				
			end
		end
	end
	
	
	
	return PartInstructions
	
end