Initial Commit

boids.lua

@@ -0,0 +1,158 @@
+-----------
+-- Boids --
+-----------
+
+local random = math.random
+
+local function average(tbl)
+    local sum = 0
+    for _,v in pairs(tbl) do -- Get the sum of all numbers in t
+      sum = sum + v
+    end
+    return sum / #tbl
+end
+
+local function average_angle(tbl)
+    local sum_sin, sum_cos = 0, 0
+    for _, v in pairs(tbl) do
+        sum_sin = sum_sin + math.sin(v)
+        sum_cos = sum_cos + math.cos(v)
+    end
+    return math.atan2(sum_sin, sum_cos)
+end
+
+local vec_dist = vector.distance
+local vec_dir = vector.direction
+local vec_len = vector.length
+local vec_add = vector.add
+local vec_multi = vector.multiply
+local vec_normal = vector.normalize
+local vec_divide = vector.divide
+local function vec_raise(v, n)
+    return {x = v.x, y = v.y + n, z = v.z}
+end
+
+local function get_average_pos(vectors)
+    local sum = {x = 0, y = 0, z = 0}
+    for _, vec in pairs(vectors) do sum = vec_add(sum, vec) end
+    return vec_divide(sum, #vectors)
+end
+
+local function dist_2d(pos1, pos2)
+    local a = vector.new(
+        pos1.x,
+        0,
+        pos1.z
+    )
+    local b = vector.new(
+        pos2.x,
+        0,
+        pos2.z
+    )
+    return vec_dist(a, b)
+end
+
+local yaw2dir = minetest.yaw_to_dir
+local dir2yaw = minetest.dir_to_yaw
+
+-- Refresh Boid Leader --
+
+local last_boid_refresh = minetest.get_us_time()
+
+-- Get Boid Members --
+
+-- This function scans within
+-- a set radius for potential
+-- boid members, and assigns
+-- a leader. A new leader
+-- is only assigned every 12
+-- seconds or if a new mob
+-- is in the boid.
+
+function creatura.get_boid_members(pos, radius, name)
+    local objects = minetest.get_objects_inside_radius(pos, radius)
+    if #objects < 2 then return {} end
+    local members = {}
+    local max_boid = minetest.registered_entities[name].max_boids or 7
+    for i = 1, #objects do
+        if #members > max_boid then break end
+        local object = objects[i]
+        if object:get_luaentity()
+        and object:get_luaentity().name == name then
+            object:get_luaentity().boid_heading = math.rad(random(360))
+            table.insert(members, object)
+        end
+    end
+    return members
+end
+
+-- Calculate Boid angles and offsets.
+
+local function debugpart(pos, time, part)
+    minetest.add_particle({
+        pos = pos,
+        expirationtime = time or 0.2,
+        size = 8,
+        glow = 16,
+        texture = part or "creatura_particle_red.png"
+    })
+end
+
+function creatura.get_boid_angle(self, boid, range) -- calculates boid angle based on seperation, alignment, and cohesion
+    local pos = self.object:get_pos()
+    local boids = boid or creatura.get_boid_members(pos, range or 4, self.name)
+    if #boids < 3 then return end
+    local yaw = self.object:get_yaw()
+    local lift = self.object:get_velocity().y
+    -- Add Boid data to tables
+    local closest_pos
+    local positions = {}
+    local angles = {}
+    local lifts = {}
+    for i = 1, #boids do
+        local boid = boids[i]
+        if boid:get_pos() then
+            local boid_pos = boid:get_pos()
+            local boid_yaw = boid:get_yaw()
+            table.insert(positions, boid_pos)
+            if boid ~= self.object then
+                table.insert(lifts, boid:get_velocity().y)
+                table.insert(angles, boid:get_yaw())
+                if not closest_pos
+                or vec_dist(pos, boid_pos) < vec_dist(pos, closest_pos) then
+                    closest_pos = boid_pos
+                end
+            end
+        end
+    end
+    if #positions < 3 then return end  
+    local center = get_average_pos(positions)
+    local dir2closest = vec_dir(pos, closest_pos)
+    -- Calculate Parameters
+    local alignment = average_angle(angles)
+    center = vec_add(center, yaw2dir(alignment))
+    local dir2center = vec_dir(pos, center)
+    local seperation = dir2yaw(vector.multiply(dir2center, -1))
+    local cohesion = dir2yaw(dir2center)
+    local params = {alignment}
+    if self.boid_heading then
+        table.insert(params, yaw + self.boid_heading)
+    end
+    if dist_2d(pos, closest_pos) < (self.boid_seperation or self.width * 3) then -- seperation is causing north issue
+        table.insert(params, seperation)
+    elseif dist_2d(pos, center) > (#boids * 0.33) * (self.boid_seperation or self.width * 3) then
+        table.insert(params, cohesion)
+    end
+    -- Vertical Params
+    local vert_alignment = average(lifts)
+    local vert_seperation = (self.speed or 2) * -dir2closest.y
+    local vert_cohesion = (self.speed or 2) * dir2center.y
+    local vert_params = {vert_alignment}
+    if math.abs(pos.y - closest_pos.y) < (self.boid_seperation or self.width * 3) then
+        table.insert(vert_params, vert_seperation)
+    elseif math.abs(pos.y - closest_pos.y) > 1.5 * (self.boid_seperation or self.width * 3) then
+        table.insert(vert_params, vert_cohesion + (lift - vert_cohesion) * 0.1)
+    end
+    self.boid_heading = nil
+    return average_angle(params), average_angle(vert_params)
+end