Added untested plane physics

entities/plane.lua

@@ -2,8 +2,26 @@ Class = require 'hump.class'
 require 'entities/physicsentity'
 require 'settings'
 require 'entities/debug'
+Matrix = require 'matrix'
 VectorLight = require 'hump/vector-light'
 
+local function sign(v)
+    if v >= 0 then
+        return 1
+    else
+        return -1
+    end
+end
+
+local fwd_frict_coeff = 0.2
+local nor_frict_coeff = 2.0
+local tail_frict_coeff = 0.5
+local head_area = 1.0
+local plane_area = 10.0
+local tail_area = 0.2
+local turn_speed = 0.2
+local wing_lift = 0.1
+
 Plane = Class{
     __includes = PhysicsEntity,
 
@@ -38,10 +56,72 @@ Plane = Class{
         self.x, self.y = self.fixture:getBoundingBox()
         self.angle = self.body:getAngle()
 
+        local vel_x, vel_y = self.body:getLinearVelocity()
+        local abs_vel = VectorLight.len2(vel_x, vel_y)
+
+        -- -- local base = 
+        -- let base = V.base (V.vec_of_ang (~-(body#get_angle))) in
+        local base = Matrix{{math.cos(-self.angle), math.sin(-self.angle)}, {math.cos(-self.angle + math.pi / 2), math.sin(-self.angle + math.pi / 2)}}
+        local to_base = function(x, y) 
+            return Matrix.mul(Matrix{{x}, {y}}, base)
+        end
+        
+        local fwd_x, fwd_y = VectorLight.rotate(self.angle, 1, 0)
+        local normal_x, normal_y = VectorLight.rotate(self.angle, 0, 1)
+        local normal_unit_x, normal_unit_y = VectorLight.div(VectorLight.len(normal_x, normal_y), normal_x, normal_y)
+        local fwd_vel = VectorLight.dot(vel_x, vel_y, fwd_x, fwd_y)
+        local normal_vel = VectorLight.dot(vel_x, vel_y, normal_x, normal_y)
+
+        local tail_speed = self.body:getAngularVelocity() * math.pi * 2.0 * self.xsize / 2.0
+        local tail_vel = to_base(0, tail_speed) -- hmm?! not tail_speed, 0?
+        local abs_tail_vel_x, abs_tail_vel_y = VectorLight.add(vel_x, vel_y, tail_vel[1][1], tail_vel[2][1])
+        --print("absolute tail veloicty: ", abs_tail_vel_x, abs_tail_vel_y)
+
+        local head_angle = self.angle
+
+        local rel_force = function(label, force, at)
+            self.body:applyForce(force, at)
+        end
+        
+        local speed_angle
+        if abs_vel < 1.0 then
+            speed_angle = head_angle
+        else
+            speed_angle = math.atan2(vel_y, vel_x)
+        end
+
+        local air_wing_angle
+        local tmp
+        tmp = head_angle - speed_angle
+        if tmp > math.pi then
+            air_wing_angle = tmp - 2.0 * math.pi
+        else
+            air_wing_angle = tmp
+        end
+
+        local lift = function(angle) 
+            return 1.68429 * math.exp(-math.pow(angle / math.pi * 180.0 -17.3801, 2.0) / math.pow(2.0*15.0, 2.0))
+        end
+
+        local lift_coeff = lift(air_wing_angle)
+
+        print("lift coeff: ", lift_coeff)
+
+        -- motor
         local dx, dy = VectorLight.rotate(self.angle, self.motor_power * 10.0 * PIXELS_PER_METER, 0)
         self.body:applyForce(dx, dy);
         table.insert(debugVectors, DebugVector(self.body:getX(), self.body:getY(), dx, dy))
 
+        -- Air friction (and drag?) opposes movement towards plane velocity normal also
+        -- hdd drag
+        local hddrag_x, hddrag_y = VectorLight.mul(nor_frict_coeff * math.pow(normal_vel, 2.0) * sign(normal_vel), -normal_unit_x, -normal_unit_y)
+        --        self.body:applyForce()
+        local b = to_base(-1.0, 0.0)
+        self.body:applyForce(hddrag_x, hddrag_y, b[1][1], b[2][1])
+        
+        local lift_x, lift_y = VectorLight.mul(wing_lift * math.pow(fwd_vel, 2.0) * lift_coeff, normal_unit_x, normal_unit_y)
+        self.body:applyForce(lift_x, lift_y, self.body:getX(), self.body:getY())
+
         if self.turningCcw then
             dx, dy = VectorLight.rotate(self.angle - math.pi / 2, 1000, 0)
         elseif self.turningCw then

matrix.LICENSE

@@ -0,0 +1,35 @@
+LuaMatrix License
+-----------
+
+LuaMatrix ( http://luamatrix.luaforge.net/ ) is licensed under the
+same terms as Lua (MIT license) reproduced below.  This means that
+LuaMatrix is free software and can be used for both academic and
+commercial purposes at absolutely no cost.
+
+For details and rationale, see http://www.lua.org/license.html .
+
+===============================================================================
+
+Copyright (C) 2007-2010 Michael Lutz.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+===============================================================================
+
+(end of COPYRIGHT)