speed clamping: sideways friction < 0 clamps against minimum possible backwards speed...

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@9887 d7cf8633-e32d-0410-b094-e92efae38249

diff --git a/cl_input.c b/cl_input.c
index f6d90d4f18b6fd14e2cef3eb6a1a7da134814f7a..28339a431a3eaed4268e52093d8838196112e35e 100644 (file)
--- a/cl_input.c
+++ b/cl_input.c
@@ -438,8 +438,8 @@ cvar_t cl_movement_accelerate = {0, "cl_movement_accelerate", "10", "how fast yo
 cvar_t cl_movement_airaccelerate = {0, "cl_movement_airaccelerate", "-1", "how fast you accelerate while in the air (should match sv_airaccelerate), if less than 0 the cl_movement_accelerate variable is used instead"};
 cvar_t cl_movement_wateraccelerate = {0, "cl_movement_wateraccelerate", "-1", "how fast you accelerate while in water (should match sv_wateraccelerate), if less than 0 the cl_movement_accelerate variable is used instead"};
 cvar_t cl_movement_jumpvelocity = {0, "cl_movement_jumpvelocity", "270", "how fast you move upward when you begin a jump (should match the quakec code)"};
-cvar_t cl_movement_airaccel_qw = {0, "cl_movement_airaccel_qw", "1", "ratio of QW-style air control as opposed to simple acceleration (should match sv_airaccel_qw)"};
-cvar_t cl_movement_airaccel_sideways_friction = {0, "cl_movement_airaccel_sideways_friction", "0", "anti-sideways movement stabilization (should match sv_airaccel_sideways_friction)"};
+cvar_t cl_movement_airaccel_qw = {0, "cl_movement_airaccel_qw", "1", "ratio of QW-style air control as opposed to simple acceleration (reduces speed gain when zigzagging) (should match sv_airaccel_qw); when < 0, the speed is clamped against the maximum allowed forward speed after the move"};
+cvar_t cl_movement_airaccel_sideways_friction = {0, "cl_movement_airaccel_sideways_friction", "0", "anti-sideways movement stabilization (should match sv_airaccel_sideways_friction); when < 0, only so much friction is applied that braking (by accelerating backwards) cannot be stronger"};
 
 cvar_t in_pitch_min = {0, "in_pitch_min", "-90", "how far downward you can aim (quake used -70"};
 cvar_t in_pitch_max = {0, "in_pitch_max", "90", "how far upward you can aim (quake used 80"};
@@ -1104,31 +1104,41 @@ void CL_ClientMovement_Physics_CPM_PM_Aircontrol(cl_clientmovement_state_t *s, v
 
 void CL_ClientMovement_Physics_PM_Accelerate(cl_clientmovement_state_t *s, vec3_t wishdir, vec_t wishspeed, vec_t wishspeed0, vec_t accel, vec_t accelqw, vec_t sidefric)
 {
-       vec_t vel_straight, vel_z;
+       vec_t vel_straight;
+       vec_t vel_z;
        vec3_t vel_perpend;
-       vec_t addspeed;
-       vec_t savespeed;
+       vec_t step;
+       vec3_t vel_xy;
+       vec_t vel_xy_current;
+       vec_t vel_xy_backward, vel_xy_forward;
+       qboolean speedclamp;
+
+       speedclamp = (accelqw < 0);
+       if(speedclamp)
+               accelqw = -accelqw;
 
        if(cl.moveflags & MOVEFLAG_Q2AIRACCELERATE)
                wishspeed0 = wishspeed; // don't need to emulate this Q1 bug
 
-       savespeed = VectorLength2(s->velocity);
-
        vel_straight = DotProduct(s->velocity, wishdir);
        vel_z = s->velocity[2];
-       VectorMA(s->velocity, -vel_straight, wishdir, vel_perpend); vel_perpend[2] -= vel_z;
+       VectorCopy(s->velocity, vel_xy); vel_xy[2] -= vel_z;
+       VectorMA(vel_xy, -vel_straight, wishdir, vel_perpend);
+
+       step = accel * s->cmd.frametime * wishspeed0;
+
+       vel_xy_current  = VectorLength(vel_xy);
+       vel_xy_forward  = vel_xy_current + bound(0, wishspeed - vel_xy_current, step) * accelqw + step * (1 - accelqw);
+       vel_xy_backward = vel_xy_current - bound(0, wishspeed + vel_xy_current, step) * accelqw - step * (1 - accelqw);
+
+       vel_straight    = vel_straight   + bound(0, wishspeed - vel_straight,   step) * accelqw + step * (1 - accelqw);
 
-       addspeed = wishspeed - vel_straight;
-       if(addspeed > 0)
-               vel_straight = vel_straight + min(addspeed, accel * s->cmd.frametime * wishspeed0) * accelqw;
-       if(wishspeed > 0)
-               vel_straight = vel_straight + min(wishspeed, accel * s->cmd.frametime * wishspeed0) * (1 - accelqw);
-       
        if(sidefric < 0 && VectorLength2(vel_perpend))
+               // negative: only apply so much sideways friction to stay below the speed you could get by "braking"
        {
                vec_t f, fmin;
                f = 1 - s->cmd.frametime * wishspeed * sidefric;
-               fmin = (savespeed - vel_straight*vel_straight) / VectorLength2(vel_perpend);
+               fmin = (vel_xy_backward*vel_xy_backward - vel_straight*vel_straight) / VectorLength2(vel_perpend);
                if(fmin <= 0)
                        VectorScale(vel_perpend, f, vel_perpend);
                else
@@ -1138,6 +1148,17 @@ void CL_ClientMovement_Physics_PM_Accelerate(cl_clientmovement_state_t *s, vec3_
                VectorScale(vel_perpend, 1 - s->cmd.frametime * wishspeed * sidefric, vel_perpend);
 
        VectorMA(vel_perpend, vel_straight, wishdir, s->velocity);
+
+       if(speedclamp)
+       {
+               vel_xy_current = min(VectorLength(s->velocity), vel_xy_forward);
+               if(vel_xy_current > 0) // prevent division by zero
+               {
+                       VectorNormalize(s->velocity);
+                       VectorScale(s->velocity, vel_xy_current, s->velocity);
+               }
+       }
+
        s->velocity[2] += vel_z;
 }
 

diff --git a/sv_main.c b/sv_main.c
index 379a8ce1f86a3cb053202b8f93e780f08d39e603..6c65024388e224be23ca84b215c9bfa98bf6aa6c 100644 (file)
--- a/sv_main.c
+++ b/sv_main.c
@@ -47,8 +47,8 @@ cvar_t slowmo = {0, "slowmo", "1.0", "controls game speed, 0.5 is half speed, 2
 
 cvar_t sv_accelerate = {0, "sv_accelerate", "10", "rate at which a player accelerates to sv_maxspeed"};
 cvar_t sv_aim = {CVAR_SAVE, "sv_aim", "2", "maximum cosine angle for quake's vertical autoaim, a value above 1 completely disables the autoaim, quake used 0.93"};
-cvar_t sv_airaccel_qw = {0, "sv_airaccel_qw", "1", "ratio of QW-style air control as opposed to simple acceleration"};
-cvar_t sv_airaccel_sideways_friction = {0, "sv_airaccel_sideways_friction", "", "anti-sideways movement stabilization (reduces speed gain when zigzagging)"};
+cvar_t sv_airaccel_qw = {0, "sv_airaccel_qw", "1", "ratio of QW-style air control as opposed to simple acceleration; when < 0, the speed is clamped against the maximum allowed forward speed after the move"};
+cvar_t sv_airaccel_sideways_friction = {0, "sv_airaccel_sideways_friction", "", "anti-sideways movement stabilization (reduces speed gain when zigzagging); when < 0, only so much friction is applied that braking (by accelerating backwards) cannot be stronger"};
 cvar_t sv_airaccelerate = {0, "sv_airaccelerate", "-1", "rate at which a player accelerates to sv_maxairspeed while in the air, if less than 0 the sv_accelerate variable is used instead"};
 cvar_t sv_airstopaccelerate = {0, "sv_airstopaccelerate", "0", "when set, replacement for sv_airaccelerate when moving backwards"};
 cvar_t sv_airstrafeaccelerate = {0, "sv_airstrafeaccelerate", "0", "when set, replacement for sv_airaccelerate when just strafing"};