From 1643b4e1a565cd5c0569038bf767f51c13675c5e Mon Sep 17 00:00:00 2001
From: fnicon <mybeddrom@gmail.com>
Date: Sun, 22 Mar 2026 13:33:58 +0900
Subject: [PATCH] add velocity_flow

---
 game/love_src/src/new/components/racer.lua | 30 ++++++++++++++++------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/game/love_src/src/new/components/racer.lua b/game/love_src/src/new/components/racer.lua
index 8aef97d..6c0bbf4 100644
--- a/game/love_src/src/new/components/racer.lua
+++ b/game/love_src/src/new/components/racer.lua
@@ -63,6 +63,26 @@ function get(s)
     s.data.streamline
 end
 
+local function rotate_vector(x0, y0, theta)
+  local x1 = x0 * math.cos(theta) - y0 * math.sin(theta)
+  local y1 = x0 * math.sin(theta) + y0 * math.cos(theta)
+  return vm.vec2(x1, y1)
+end
+
+local function velocity_flow(dt, force, mass, velocity, max_speed, min_speed)
+  if (mass == 0) then
+    mass = 1
+  end
+  local a = force * dt / mass
+
+  -- local theta_a = rotate_vector(force[1], 0, force[2])
+  local new_velocity = velocity + a
+  new_velocity[1] = vm.clamp(new_velocity[1], min_speed, max_speed)
+  new_velocity[2] = vm.clamp(new_velocity[2], min_speed, max_speed)
+
+  return new_velocity
+end
+
 function world:update_race(dt)
   local x, y = self.data.pos[1], self.data.pos[2]
   local or_x, or_y = self.data.orientation[1], self.data.orientation[2]
@@ -83,16 +103,10 @@ function world:update_race(dt)
     magic_w.drag_boost, magic_w.drag_halt,
     magic_w.inertia, magic_w.centrifugal
   )
+  self.data.velocity = velocity_flow(dt, force, mass, velocity, max_speed, min_speed)
 
-  if (mass == 0) then
-    mass = 1
-  end
-  local a = force * dt / mass
-
-  self.data.velocity = self.data.velocity + a
-  self.data.velocity[1] = vm.clamp(self.data.velocity[1], min_speed, max_speed)
   -- if (self.data.velocity[1] ~= 0) then
-    self.data.pos = self.data.pos + self.data.velocity
+  self.data.pos = self.data.pos + self.data.velocity
   -- end
 
   self.data.inertia = force