From a1df463a16f4c37ecc8de5bf5dcd3114bfb1681f Mon Sep 17 00:00:00 2001
From: Kistaro Windrider <kistaro@gmail.com>
Date: Sun, 14 Jan 2024 19:57:22 -0800
Subject: [PATCH] braking distance and visualization. bad calculation

the visualization is really helpful for showing me that I fucked up my math
---
 autobrake_test.p8 | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/autobrake_test.p8 b/autobrake_test.p8
index bf88058..07a9102 100644
--- a/autobrake_test.p8
+++ b/autobrake_test.p8
@@ -126,6 +126,12 @@ function ship:draw()
  else
   spr(1,self.x,self.y)
  end
+
+ if (self.dx == 0) return
+ local bd, f = brake_dist(self.dx, self.thrust + self.drag)
+ local bdx = self.x+bd-2
+ spr(3, bdx,self.y-3)
+ print(tostr(f), bdx, self.y - 8, 14)
 end
 
 function calc_velocity(v0, t, vmax, drag)
@@ -163,9 +169,21 @@ constraints = {
 
 function constraints:constrain(s, want)
  self.color=10
+
+ local v1 = calc_velocity(s.dx, want, s.maxspd, s.drag)
+ local bd, bf = brake_dist(v1, s.thrust + s.drag)
+
  return want
 end
 
+function brake_dist(v0, brake_max)
+ local tri_frames = abs(v0/brake_max)&-1
+ local chunks = tri_frames * (tri_frames - 1) >> 1
+ local chunk_zone = chunks * brake_max
+ local overage = v0 - chunk_zone
+ return chunk_zone + overage * (tri_frames + 1) * -sgn(v0), (overage > 0) and tri_frames + 1 or tri_frames
+end
+
 function constraints:cycle()
  if self.ctype=="bounds" then
   self.ctype="point"
@@ -201,10 +219,10 @@ end
 -- todo: spark ring buffer
 
 __gfx__
-00000000800000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-00000000006666000080000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+000000008000000000080000a000a000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00000000006666000080000009090000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000067777600800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-00000000675555758008888000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-00000000675000750800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+00000000675555758008888009090000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
+000000006750007508000000a000a000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000067777500080000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 00000000005555000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000