WIP

workshop/steps/10-move-and-slide/README.md

@@ -6,14 +6,15 @@ give you the skeleton — you write the code.
 
 ## The idea
 
-A single collision doesn't end the frame (step 08's "leftover that matters"). You
-hit a wall at `t = 0.3`, slide, and **70% of the frame is still owed** — during
-which you might hit *another* wall, slide again, and so on. So moving is a small
-**loop**: sweep → stop at the nearest hit → slide → repeat with the leftover time.
+A single collision doesn't end the frame (step 08's "leftover that matters").
+You hit a wall at `t = 0.3`, slide, and **70% of the frame is still owed** —
+during which you might hit _another_ wall, slide again, and so on. So moving is
+a small **loop**: sweep → stop at the nearest hit → slide → repeat with the
+leftover time.
 
 We loop a **maximum of 4 times** (your engine's cap) — enough to handle a corner
-(hit a wall, slide, hit the perpendicular wall, slide, stop) without ever risking
-an infinite loop.
+(hit a wall, slide, hit the perpendicular wall, slide, stop) without ever
+risking an infinite loop.
 
 ## The algorithm
 
@@ -46,29 +47,32 @@ return pos
 
 Two things worth understanding, not just copying:
 
-- **`move = vel * timeLeft`.** `vel` is a *full-frame* displacement (how far you'd
-  go in a whole frame at this velocity). You only have `timeLeft` of the frame
-  left, so the actual travel is `vel * timeLeft`. `sweptAABB`'s returned `time` is
-  then a fraction *of that sub-move*, which is why `pos + move * time` is correct.
+- **`move = vel * timeLeft`.** `vel` is a _full-frame_ displacement (how far
+  you'd go in a whole frame at this velocity). You only have `timeLeft` of the
+  frame left, so the actual travel is `vel * timeLeft`. `sweptAABB`'s returned
+  `time` is then a fraction _of that sub-move_, which is why `pos + move * time`
+  is correct.
 
-- **The `EPSILON` backoff** (`max(0, hit.time - EPSILON)`). Stop a hair *short* of
-  the wall. If you land exactly on it, floating-point error can leave you a sliver
-  inside — and next iteration's sweep would start already-overlapping, reporting a
-  garbage negative-time "collision" that makes you stick or jitter. That tiny gap
-  is exactly the `Math.max(0, time - EPSILON)` in your real `moveAndSlide`. Now you
-  know *why* it's there. `EPSILON` is provided in `given.ts`.
+- **The `EPSILON` backoff** (`max(0, hit.time - EPSILON)`). Stop a hair _short_
+  of the wall. If you land exactly on it, floating-point error can leave you a
+  sliver inside — and next iteration's sweep would start already-overlapping,
+  reporting a garbage negative-time "collision" that makes you stick or jitter.
+  That tiny gap is exactly the `Math.max(0, time - EPSILON)` in your real
+  `moveAndSlide`. Now you know _why_ it's there. `EPSILON` is provided in
+  `given.ts`.
 
-> **Moving-vs-moving (why your real engine has `velocity - otherVel`).** Here the
-> walls are static, so we sweep with plain `vel`. When the *other* body also moves,
-> you sweep in its frame of reference by using the **relative** velocity
-> `vel - otherVel` — then the exact same loop works, because from the other body's
-> point of view it's standing still. That's the only difference between this kata
-> and the full engine. The loop itself doesn't change.
+> **Moving-vs-moving (why your real engine has `velocity - otherVel`).** Here
+> the walls are static, so we sweep with plain `vel`. When the _other_ body also
+> moves, you sweep in its frame of reference by using the **relative** velocity
+> `vel - otherVel` — then the exact same loop works, because from the other
+> body's point of view it's standing still. That's the only difference between
+> this kata and the full engine. The loop itself doesn't change.
 
 ## Task
 
-Implement `moveAndSlide(box, v, walls)` in `moveAndSlide.ts`. Everything you need —
-`sweptAABB`, `slide`, the vector ops, `EPSILON` — is finished in `given.ts`.
+Implement `moveAndSlide(box, v, walls)` in `moveAndSlide.ts`. Everything you
+need — `sweptAABB`, `slide`, the vector ops, `EPSILON` — is finished in
+`given.ts`.
 
 ```sh
 bun test workshop/steps/10-move-and-slide