biters.lua

function getPossibleBiters(curve, evo)
	local ret = {}
	local totalWeight = 0
	for _,entry in pairs(curve) do
		local biter = entry.unit
		local vals = entry.spawn_points -- eg "{0.5, 0.0}, {1.0, 0.4}"
		for idx = 1,#vals do
			local point = vals[idx]
			local ref = point.evolution_factor
			local chance = point.weight
			if evo >= ref then
				local interp = 0
				if idx == #vals then
					interp = chance
				else
					interp = chance+(vals[idx+1].weight-chance)*(vals[idx+1].evolution_factor-ref)
				end
				if interp > 0 then
					table.insert(ret, {biter, interp+totalWeight})
					totalWeight = totalWeight+interp
					--game.print("Adding " .. biter .. " with weight " .. interp)
				end
				break
			end
		end
	end
	--game.print("Fake Evo " .. evo)
	--for i=1,#ret do game.print(ret[i][1] .. ": " .. ((i == 1 and 0 or ret[i-1][2]) .. " -> " .. ret[i][2])) end
	return ret, totalWeight
end

function selectWeightedBiter(biters, total)
	local f = math.random()*total
	local ret = "nil"
	local smallest = 99999999
	for i = 1,#biters do
		if f <= biters[i][2] and smallest > biters[i][2] then
			smallest = biters[i][2]
			ret = biters[i][1]
		end
	end
	--game.print("Selected " .. ret .. " with " .. f .. " / " .. total)
	return ret
end

function getSpawnedBiter(curve, evo)
	--game.print("Real Evo " .. evo)
	if math.random() < 0.5 then
		evo = evo-0.1
	end
	if math.random() < 0.25 then
		evo = evo-0.1
	end
	evo = math.max(evo, 0)
	local biters, total = getPossibleBiters(curve, evo)
	return selectWeightedBiter(biters, total)
end