cap player knockback when swarmed

src/comp/mechanical.c

@@ -45,6 +45,15 @@ void mechanical_move(entity_t *e, vec2 direction, fixed_t dt, map_t const *map)
     fixed_t friction_x = fmul(fmul(-target.x, limits->friction), dt);
     fixed_t friction_y = fmul(fmul(-target.y, limits->friction), dt);
 
+    /* Limit maximum disruption (knockback) when it reaches extremes */
+    fixed_t dv2 = fmul(m->vdx, m->vdx) + fmul(m->vdy, m->vdy);
+    fixed_t max_dv = limits->max_disruption_speed;
+    if(dv2 > fmul(max_dv, max_dv)) {
+        fixed_t dv = fsqrt(dv2);
+        m->vdx = fmul(fdiv(m->vdx, dv), max_dv);
+        m->vdy = fmul(fdiv(m->vdy, dv), max_dv);
+    }
+
     /* Get there exponentially fast */
     m->vx = target.x + friction_x + m->vdx;
     m->vy = target.y + friction_y + m->vdy;

src/comp/mechanical.h

@@ -25,6 +25,10 @@ typedef struct
     /* Dash duration (s) */
     fixed_t dash_duration;
 
+    /* Maximum disruption speed, mainly avoids extreme knockback on players
+       when attacked for multiple sides at once */
+    fixed_t max_disruption_speed;
+
 } mechanical_limits_t;
 
 typedef struct

src/enemies.c

@@ -24,6 +24,7 @@ static enemy_t const slime_1 = {
     .limits = {
         .max_speed = fix(1),
         .friction = fix(0.6),
+        .max_disruption_speed = fix(999.0),
     },
     .stats = {
         .HP = fix(1.4),
@@ -44,6 +45,7 @@ static enemy_t const bat_2 = {
     .limits = {
         .max_speed = fix(1.8),
         .friction = fix(0.8),
+        .max_disruption_speed = fix(999.0),
     },
     .stats = {
         .HP = fix(1.5),
@@ -64,6 +66,7 @@ static enemy_t const fire_slime_4 = {
     .limits = {
         .max_speed = fix(1),
         .friction = fix(0.6),
+        .max_disruption_speed = fix(999.0),
     },
     .stats = {
         .HP = fix(1.4),
@@ -84,6 +87,7 @@ static enemy_t const gunslinger_8 = {
     .limits = {
         .max_speed = fix(1.8),
         .friction = fix(0.8),
+        .max_disruption_speed = fix(999.0),
     },
     .stats = {
         .HP = fix(1.3),

src/main.c

@@ -93,6 +93,7 @@ int main(void)
             .friction = fix(0.7),
             .dash_speed = fix(20),
             .dash_duration = fix(1) / 8,
+            .max_disruption_speed = fix(3.0),
         },
         .stat_model = {
             .HP  = fix(1.5),