Use the original handling, walls and projection from the executable

Decoded from SKIDMARKS_CD32's machine code:

- Car physics: the per-frame engine/grip/steering update, gravity and
  jumps, the hill effect on the throttle, and body tilt. Replaces the
  reconstructed handling model.
- The meaning of every .set value (separate drag, grip and power for
  human and computer drivers; steering, gravity, tow hitch), and the
  six handling presets, offered by a new Handling menu option.
- Walls: the road edges are quadratic B-splines through the gates'
  ends. They match the painted road edges.
- The real projection, which lifts points by their height; the height
  map is indexed by world cells, not screen pixels.
- Tracks have one more gate than the stored count: the last gate was
  being dropped on every track.

Computer drivers now follow the road between the walls and steer like
the original's. Vehicle assets store the values as `handling`; older
files still load. Docs describe the decoded logic.

assets/vehicles/camaro.txt

@@ -4,20 +4,14 @@ name CAMARO
 driver ROD
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 54 35 32 8 7 22 22 16 49 14 53 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 200
-# acceleration and braking, world pixels per second squared
-accel 170
-brake 320
-# sideways grip (higher = less sliding)
-grip 5
-# steering rate, radians per second
-turn 3.6
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 54 35 32 8 7 22 22 16 49 14 53 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 1
-# speed and grip multiplier off the road
-offroad 0.55

assets/vehicles/caravan.txt

@@ -4,20 +4,14 @@ name CARAVAN
 driver SIMON
 # yes = towed behind cars (Caravans option) instead of driven
 trailer yes
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 2 65532 65532 1 12 10 16 14 0 0 0 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 200
-# acceleration and braking, world pixels per second squared
-accel 170
-brake 320
-# sideways grip (higher = less sliding)
-grip 5
-# steering rate, radians per second
-turn 3.6
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 2 65532 65532 1 12 10 16 14 0 0 0 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 1
-# speed and grip multiplier off the road
-offroad 0.55

assets/vehicles/cow.txt

@@ -4,20 +4,14 @@ name COW
 driver ROB
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 15 14 34 8 4 598 15 12 13 4 2003 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 170
-# acceleration and braking, world pixels per second squared
-accel 150
-brake 320
-# sideways grip (higher = less sliding)
-grip 7
-# steering rate, radians per second
-turn 4.6
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 15 14 34 8 4 598 15 12 13 4 2003 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 1.4
-# speed and grip multiplier off the road
-offroad 0.9

assets/vehicles/f1.txt

@@ -4,20 +4,14 @@ name FORMULA 1
 driver SIMON
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 60 71 30 0 6 16 24 12 58 42 29 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 240
-# acceleration and braking, world pixels per second squared
-accel 210
-brake 320
-# sideways grip (higher = less sliding)
-grip 6.5
-# steering rate, radians per second
-turn 3.7
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 60 71 30 0 6 16 24 12 58 42 29 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 0.9
-# speed and grip multiplier off the road
-offroad 0.45

assets/vehicles/midget.txt

@@ -4,20 +4,14 @@ name MIDGET
 driver ROB
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 51 21 30 16 3 45 16 13 44 13 93 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 205
-# acceleration and braking, world pixels per second squared
-accel 185
-brake 320
-# sideways grip (higher = less sliding)
-grip 4
-# steering rate, radians per second
-turn 4
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 51 21 30 16 3 45 16 13 44 13 93 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 0.85
-# speed and grip multiplier off the road
-offroad 0.6

assets/vehicles/mini.txt

@@ -4,20 +4,14 @@ name MINI
 driver ROB
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 56 24 30 12 3 24 20 12 46 10 100 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 190
-# acceleration and braking, world pixels per second squared
-accel 200
-brake 320
-# sideways grip (higher = less sliding)
-grip 5.8
-# steering rate, radians per second
-turn 4.4
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 56 24 30 12 3 24 20 12 46 10 100 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 0.8
-# speed and grip multiplier off the road
-offroad 0.55

assets/vehicles/police.txt

@@ -4,20 +4,14 @@ name POLICE
 driver SIMON
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 56 34 22 6 2 15 19 11 49 14 44 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 215
-# acceleration and braking, world pixels per second squared
-accel 180
-brake 320
-# sideways grip (higher = less sliding)
-grip 5
-# steering rate, radians per second
-turn 3.5
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 56 34 22 6 2 15 19 11 49 14 44 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 1.2
-# speed and grip multiplier off the road
-offroad 0.55

assets/vehicles/porsche.txt

@@ -4,20 +4,14 @@ name PORSCHE
 driver IMAGINE
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 56 34 22 6 2 15 21 12 49 14 44 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 225
-# acceleration and braking, world pixels per second squared
-accel 190
-brake 320
-# sideways grip (higher = less sliding)
-grip 5.2
-# steering rate, radians per second
-turn 3.6
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 56 34 22 6 2 15 21 12 49 14 44 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 1
-# speed and grip multiplier off the road
-offroad 0.55

assets/vehicles/truck.txt

@@ -4,20 +4,14 @@ name TRUCK
 driver ROD
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 55 26 28 18 2 29 20 17 54 19 35 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 195
-# acceleration and braking, world pixels per second squared
-accel 140
-brake 320
-# sideways grip (higher = less sliding)
-grip 4.2
-# steering rate, radians per second
-turn 3
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 55 26 28 18 2 29 20 17 54 19 35 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 1.8
-# speed and grip multiplier off the road
-offroad 0.75

assets/vehicles/vw.txt

@@ -4,20 +4,14 @@ name BEETLE
 driver ROB
 # yes = towed behind cars (Caravans option) instead of driven
 trailer no
-# The 16 values from the original .set file. Their meaning is not
-# decoded yet, so the game does not use them; the handling below is
-# a reconstruction.
-original 57 28 32 12 3 29 20 14 51 15 63 0 0 0 0 0
-# top speed on tarmac, world pixels per second
-top 185
-# acceleration and braking, world pixels per second squared
-accel 160
-brake 320
-# sideways grip (higher = less sliding)
-grip 4.6
-# steering rate, radians per second
-turn 3.6
-# weight in collisions
+#
+# handling: the 16 values from the original .set file, used as the
+# original game does. Counting from 1:
+#   1 2 6    computer drivers: drag, grip, power
+#   9 10 11  human drivers: drag, grip, power
+#   3 steering, 5 gravity, 7 tow hitch distance; the rest are unused.
+# Top speed = power * drag / (64 - drag) / 32 world units per frame,
+# 50 frames a second (drag below 64). Higher grip, less sliding.
+handling 57 28 32 12 3 29 20 14 51 15 63 0 0 0 0 0
+# weight when cars collide (not from the original data)
 mass 1
-# speed and grip multiplier off the road
-offroad 0.55