Rework drifting

TODO.txt

@@ -1,7 +1,8 @@
 =========== GENERAL ==============
 
-- Create a physics test map.
+- keyboard ghosting is an issue, particularly when initiating drift with brake
-- Unstuck idea: make the body non-rotating for a while?
+  (arrow keys must be used with S for braking for left drift to work) -- think
+  about what to do about this? or leave as is?
 - Map4: fix top bottom corner, making the curve is too hard -- either add ramps
   on wall or shift the down ramp further.
 - Try doing the bouncy car body? Just keep a point and its velocity, change
@@ -18,13 +19,10 @@
   data file, try to somehow hack around it (maybe just convert it to an array in
   the end?) Maybe this: make a standalone C file with the string in it that
   when compiled and run outputs the array.
-- car deglitch idea: deglitch only if the middle joint collided this frame?
 - some kinda easteregg in menu or smt
 - culling is very slow now, it showed that distance bailout can accelerate it
   a lot, try to make a more accurate bailaout and see if it's faster (watch
   out for bugs due to false positives)
-- improve the car unstucking? maybe we can just keep the position of the car
-  and ONE wheel (other joint positions can be computed)
 - maps to make:
   - there should be these maps:
     - compiled in:
@@ -36,7 +34,7 @@
   - map types:
     - purely falling map                                      DONE
     - traveling salesman kind of maze, with fans n shit       KINDA DONE
-    - city map?
+    - city map?                                               DONE
     - some kinda buggy bumpy downhill                         DONE
     - map where car starts upside down                        DONE
     - dirt map                                                DONE
@@ -47,8 +45,8 @@
     - falling tube map?                                       DONE
     - grass hills as decoration?                              DONE
     - something with multiple roads                           DONE
-    - RPG kinda map? could be in bonus maps
+    - RPG kinda map? could be in bonus maps                   KINDA DONE
-    - some speed map (mostly flat to prevent high speed bugs)
+    - some speed map (mostly flat to prevent high speed bugs) DONE
     - some (at least partially) interior map                  KINDA DONE
     - something with multiple finishes                        DONE
     - U-ramp to build speed and jump up to catch a CP (done)  DONE
@@ -84,9 +82,12 @@
 =========== HANDLED ==============
 
 - MAP4: one triangle in top section is missing!
+- Unstuck idea: make the body non-rotating for a while?
+- Create a physics test map.
 - Antibug: maybe always simulate the step with non-rotating body AND normal one
   as well -- if the car ends up bugged, use the non-rotating result?
 - Fix weird reversing.
+- car deglitch idea: deglitch only if the middle joint collided this frame?
 - CP gets often missed, would be cool to increase its radius, but also hard.
   We would have to be checking 8 cells instead of one, but even then issues
   would appear with multiple CPs next to each other (returned CP_TAKEN event).
@@ -111,6 +112,8 @@
   to be drawn? could optimize rendering and map loading a lot <-- PROLLY NOT
 - on 1st map the camera is obscured by the wall at the start, fix it somehow
   (not the best first impression) <-- shifted start pos.
+- improve the car unstucking? maybe we can just keep the position of the car
+  and ONE wheel (other joint positions can be computed)
 - replay format should probably record game version
   - also there should probably be some version system that says version of
     physics vs version of everything else; replay could only record physics

racing.h

@@ -84,9 +84,6 @@ typedef int32_t LCR_GameUnit;  ///< abstract game unit
 #define LCR_CAR_WHEEL_AIR_ROTATION_SPEED (LCR_GAME_UNIT / 32)
 #define LCR_CAR_WHEEL_GROUND_SPEED_DIV 8
 
-#define LCR_CAR_DRIFT_THRESHOLD_1 (LCR_GAME_UNIT / 4)
-#define LCR_CAR_DRIFT_THRESHOLD_0 (LCR_GAME_UNIT / 200)
-
 #define LCR_CAR_CRASH_SPEED_SMALL 400
 #define LCR_CAR_CRASH_SPEED_BIG 800
 
@@ -94,8 +91,13 @@ typedef int32_t LCR_GameUnit;  ///< abstract game unit
 #define LCR_CAR_GRASS_FACTOR 5
 #define LCR_CAR_DIRT_FACTOR  3
 #define LCR_CAR_ICE_FACTOR   1
+//#define LCR_CAR_DRIFT_FACTOR 2    ///< only affects steering friction
+
 #define LCR_CAR_DRIFT_FACTOR 2    ///< only affects steering friction
 
+#define LCR_CAR_DRIFT_THRESHOLD_1 (LCR_GAME_UNIT / 10)
+#define LCR_CAR_DRIFT_THRESHOLD_0 (LCR_GAME_UNIT / 227)
+
 #define LCR_CAR_JOINTS 5
 #define LCR_CAR_CONNECTIONS 10
 
@@ -1122,7 +1124,7 @@ int _LCR_racingCarShapeOK(void)
           LCR_racing.carBody.connections[i].joint1].position,
         LCR_racing.carBody.joints[
           LCR_racing.carBody.connections[i].joint2].position),
-      LCR_racing.carBody.connections[i].length) < TPE_F / 16; // TODO: const
+      LCR_racing.carBody.connections[i].length) < TPE_F / 16; // 16: magic con.
 
   return r;
 }
@@ -1140,6 +1142,7 @@ uint32_t LCR_racingStep(unsigned int input)
   uint8_t groundMat = LCR_BLOCK_MATERIAL_CONCRETE; // material under wheels
   uint8_t onAccel = 0; // standing on accelerator?
   int groundBlockIndex = -1;
+  TPE_Unit driftFriction = 0; // average wheel friction (absolute value)
 
   if (LCR_racing.playingReplay)
   {
@@ -1182,7 +1185,7 @@ uint32_t LCR_racingStep(unsigned int input)
     LCR_racing.carBody.joints[4].velocity[2]);
 
   /* Apply gravity like this: if all wheels are on ground, we don't apply
-    gravity to roof. This helps prevent sliding. */
+    gravity to roof. This helps prevent sliding when standing still. */
 
   for (int i = 0; i < 5; ++i)
     if (i < 4 || (((LCR_racing.wheelCollisions |
@@ -1316,8 +1319,6 @@ uint32_t LCR_racingStep(unsigned int input)
       }
     }
 
-    TPE_Unit driftFriction = 0; // average wheel friction (absolute value)
-
     for (int i = 0; i < 4; ++i)
       if (LCR_racing.wheelCollisions & (0x11 << i)) // wheel on ground?
       {
@@ -1359,19 +1360,6 @@ uint32_t LCR_racingStep(unsigned int input)
 
     driftFriction /= 4; // divide by 4 wheels
 
-    if ((!LCR_racing.carDrifting) &&
-      driftFriction > LCR_CAR_DRIFT_THRESHOLD_1)
-    {
-      LCR_LOG2("drift start");
-      LCR_racing.carDrifting = 1;
-    }
-    else if (LCR_racing.carDrifting &&
-      driftFriction < LCR_CAR_DRIFT_THRESHOLD_0)
-    {
-      LCR_LOG2("drift end");
-      LCR_racing.carDrifting = 0;
-    }
-
     if (steering &&
       (input & (LCR_RACING_INPUT_FORW | LCR_RACING_INPUT_BACK)) &&
       (LCR_racing.wheelCollisions & 0x33))
@@ -1386,6 +1374,23 @@ uint32_t LCR_racingStep(unsigned int input)
     }
   }
 
+  if ((!LCR_racing.carDrifting) &&
+    driftFriction > 
+     (LCR_CAR_DRIFT_THRESHOLD_1 >> (( // back key initiates drift easily
+      ((input & (LCR_RACING_INPUT_FORW | LCR_RACING_INPUT_BACK))
+      == (LCR_RACING_INPUT_FORW | LCR_RACING_INPUT_BACK))) << 2)))
+  {
+    LCR_LOG1("drift start");
+    LCR_racing.carDrifting = 1;
+  }
+  else if (LCR_racing.carDrifting &&
+    (driftFriction < LCR_CAR_DRIFT_THRESHOLD_0 ||
+    LCR_racingGetCarSpeedUnsigned() < 5))
+  {
+    LCR_LOG1("drift end");
+    LCR_racing.carDrifting = 0;
+  }
+
   if ((!(input & LCR_RACING_INPUT_LEFT)) &&
     (!(input & LCR_RACING_INPUT_RIGHT)))
     LCR_racing.wheelSteer /= 2;
@@ -1437,7 +1442,7 @@ uint32_t LCR_racingStep(unsigned int input)
     if ((LCR_racing.carBody.flags & TPE_BODY_FLAG_UNRESOLVED) ||
       !_LCR_racingCarShapeOK()) // bad?
     {
-      LCR_LOG1("car bad, simplifying physics");
+      LCR_LOG2("using simplified physics");
 
       for (int i = 0; i < LCR_CAR_JOINTS; ++i) // use the first step positions
         LCR_racing.carBody.joints[i] = joints[i];