code: add vehicle handling

code/game/src/entity_view.c

@@ -22,6 +22,9 @@ pkt_desc pkt_entity_view_desc[] = {
     { PKT_HALF(entity_view, hp) },
     { PKT_HALF(entity_view, max_hp) },
     
+    { PKT_KEEP_IF(entity_view, kind, EKIND_VEHICLE, 1) }, // NOTE(zaklaus): keep for vehicles
+    { PKT_HALF(entity_view, heading) },
+    
     { PKT_END }, 
 };
 

code/game/src/entity_view.h

@@ -48,6 +48,9 @@ typedef struct entity_view {
     uint8_t is_dirty;
     int64_t tex;
     
+    // NOTE(zaklaus): vehicle
+    float heading, theading;
+    
     // NOTE(zaklaus): internals
     uint8_t layer_id;
     uint64_t last_update;

code/game/src/platform_raylib.c

@@ -115,6 +115,7 @@ void lerp_entity_positions(uint64_t key, entity_view * data);
 void do_entity_fadeinout(uint64_t key, entity_view * data);
 
 float zpl_lerp(float,float,float);
+float zpl_to_degrees(float);
 
 void platform_render() {
     profile(PROF_ENTITY_LERP) {
@@ -220,9 +221,9 @@ void DEBUG_draw_entities(uint64_t key, entity_view * data) {
         case EKIND_VEHICLE: {
             float x = data->x;
             float y = data->y;
-            float const w = 50;
+            float const w = 80;
-            float const h = 80;
+            float const h = 50;
-            DrawRectanglePro((Rectangle){x,y,w,h}, (Vector2){w/2.0f,h/2.0f}, 0.0f, ColorAlpha(RED, data->tran_time));
+            DrawRectanglePro((Rectangle){x,y,w,h}, (Vector2){w/2.0f,h/2.0f}, zpl_to_degrees(data->heading), ColorAlpha(RED, data->tran_time));
         }break;
         default:break;
     }
@@ -237,9 +238,11 @@ void lerp_entity_positions(uint64_t key, entity_view *data) {
 #if 1
         data->x = smooth_val(data->x, data->tx, view->delta_time[data->layer_id]);
         data->y = smooth_val(data->y, data->ty, view->delta_time[data->layer_id]);
+        data->heading = smooth_val_spherical(data->heading, data->theading, view->delta_time[data->layer_id]);
 #else
         data->x = data->tx;
         data->y = data->ty;
+        data->heading = data->theading;
 #endif
     }
 }

code/game/src/prediction.c

@@ -11,6 +11,26 @@ static inline float map_factor(float x) {
     return 1.0f - x*x*x*x*x*x*x*x;
 }
 
+static inline float base_angle(float x) {
+    while (x > ZPL_TAU) x -= ZPL_TAU;
+    while (x < 0.0f) x += ZPL_TAU;
+    return x;
+}
+
+static inline float spherical_lerp(float a, float b, float t) {
+    a = base_angle(a);
+    b = base_angle(b);
+    float d = b - a;
+    
+    if (d < -ZPL_PI) {
+        b += ZPL_TAU;
+    } else if (d > ZPL_PI) {
+        b -= ZPL_TAU;
+    }
+    
+    return base_angle(zpl_lerp(a, b, t));
+}
+
 float smooth_val(float cur, float tgt, uint64_t dt) {
     float factor = zpl_clamp01(map_factor(zpl_unlerp(dt, WORLD_TRACKER_UPDATE_FAST_MS, WORLD_TRACKER_UPDATE_SLOW_MS)));
     
@@ -24,15 +44,24 @@ float smooth_val(float cur, float tgt, uint64_t dt) {
     return zpl_lerp(cur, tgt, zpl_lerp(PREDICT_SMOOTH_FACTOR_LO, PREDICT_SMOOTH_FACTOR_HI, factor));
 }
 
+float smooth_val_spherical(float cur, float tgt, uint64_t dt) {
+    float factor = zpl_clamp01(map_factor(zpl_unlerp(dt, WORLD_TRACKER_UPDATE_FAST_MS, WORLD_TRACKER_UPDATE_SLOW_MS)));
+    
+    return spherical_lerp(cur, tgt, zpl_lerp(PREDICT_SMOOTH_FACTOR_LO, PREDICT_SMOOTH_FACTOR_HI, factor));
+}
+
 void predict_receive_update(entity_view *d, entity_view *data) {
     if (d && data->flag & EFLAG_INTERP) {
         // NOTE(zaklaus): store target pos but keep x,y unchanged
         float tx = data->x;
         float ty = data->y;
+        float theading = data->heading;
         data->x = d->x;
         data->y = d->y;
+        data->heading = d->heading;
         data->tx = tx;
         data->ty = ty;
+        data->theading = theading;
     }
     
     data->tran_effect = d->tran_effect;

code/game/src/prediction.h

@@ -2,4 +2,5 @@
 #include "entity_view.h"
 
 float smooth_val(float cur, float tgt, uint64_t dt);
-void predict_receive_update(entity_view *d, entity_view *data);
+void predict_receive_update(entity_view *d, entity_view *data);
+float smooth_val_spherical(float cur, float tgt, uint64_t dt);

code/game/src/vehicle.c

@@ -8,7 +8,9 @@
 uint64_t vehicle_spawn(void) {    
     ecs_entity_t e = entity_spawn(EKIND_VEHICLE);
     
-    ecs_set(world_ecs(), e, Vehicle, {0});
+    Vehicle *veh = ecs_get_mut(world_ecs(), e, Vehicle, NULL);
+    zpl_zero_item(veh);
+    veh->wheel_base = 60.0f;
     return (uint64_t)e;
 }
 

code/game/src/world/world.c

@@ -45,6 +45,11 @@ entity_view world_build_entity_view(int64_t e) {
         view.max_hp = health->max_hp;
     }
     
+    if (ecs_get(world_ecs(), e, Vehicle)) {
+        Vehicle const* veh = ecs_get(world_ecs(), e, Vehicle);
+        view.heading = veh->heading;
+    }
+    
     if (ecs_get(world_ecs(), e, Chunk)) {
         Chunk *chpos = ecs_get_mut(world_ecs(), e, Chunk, 0);
         view.x = chpos->x;

code/game/src/world_view.c

@@ -59,6 +59,7 @@ int32_t tracker_read_create(librg_world *w, librg_event *e) {
     if (data.flag & EFLAG_INTERP) {
         data.tx = data.x;
         data.ty = data.y;
+        data.theading = data.heading;
     }
     entity_view_update_or_create(&view->entities, entity_id, data);
     entity_view_mark_for_fadein(&view->entities, entity_id);

code/modules/modules/components.h

@@ -51,6 +51,11 @@ ECS_STRUCT(Classify, {
 
 ECS_STRUCT(Vehicle, {
                uint64_t seats[4];
+               
+               float speed;
+               float heading;
+               float steer;
+               float wheel_base;
            });
 
 ECS_COMPONENT_EXTERN(Chunk);

code/modules/modules/systems.c

@@ -201,12 +201,35 @@ void EnterOrLeaveVehicle(ecs_iter_t *it) {
     }
 }
 
+#define VEHICLE_MAX_SPEED 500.0f
+#define VEHICLE_ACCEL 2.1f
+#define VEHICLE_STEER 0.01f
+
 void VehicleHandling(ecs_iter_t *it) {
     Vehicle *veh = ecs_column(it, Vehicle, 1);
     Position *p = ecs_column(it, Position, 2);
     Velocity *v = ecs_column(it, Velocity, 3);
     
     for (int i = 0; i < it->count; i++) {
+        Vehicle *car = &veh[i];
+        car->speed *= 0.99f;
+        car->steer *= 0.97f;
+        
+        float fr_x = p[i].x + (car->wheel_base/2.0f) * zpl_cos(car->heading);
+        float fr_y = p[i].y + (car->wheel_base/2.0f) * zpl_sin(car->heading);
+        
+        float bk_x = p[i].x - (car->wheel_base/2.0f) * zpl_cos(car->heading);
+        float bk_y = p[i].y - (car->wheel_base/2.0f) * zpl_sin(car->heading);
+        
+        bk_x += car->speed * zpl_cos(car->heading);
+        bk_y += car->speed * zpl_sin(car->heading);
+        fr_x += car->speed * zpl_cos(car->heading + zpl_to_radians(car->steer));
+        fr_y += car->speed * zpl_sin(car->heading + zpl_to_radians(car->steer));
+        
+        v[i].x = (fr_x + bk_x) / 2.0f - p[i].x;
+        v[i].y = (fr_y + bk_y) / 2.0f - p[i].y;
+        car->heading = zpl_arctan2(fr_y - bk_y, fr_x - bk_x);
+        
         for (int j = 0; j < 4; j++) {
             // NOTE(zaklaus): Perform seat cleanup
             if (!ecs_is_alive(world_ecs(), veh[i].seats[j])) {
@@ -219,15 +242,19 @@ void VehicleHandling(ecs_iter_t *it) {
             // NOTE(zaklaus): Update passenger position
             {
                 Position *p2 = ecs_get_mut(world_ecs(), pe, Position, NULL);
+                Velocity *v2 = ecs_get_mut(world_ecs(), pe, Velocity, NULL);
                 *p2 = p[i];
+                *v2 = v[i];
             }
             
             // NOTE(zaklaus): Handle driver input
             if (j == 0) {
-                // TODO(zaklaus): Be lazy about it for now, implement wheels later
                 Input const* in = ecs_get(world_ecs(), pe, Input);
-                v[i].x += in->x;
+                
-                v[i].y += in->y;
+                car->speed += in->y * VEHICLE_ACCEL;
+                car->speed = zpl_clamp(car->speed, -VEHICLE_MAX_SPEED, VEHICLE_MAX_SPEED);
+                car->steer += in->x * -VEHICLE_STEER * (zpl_abs(car->speed*2.5f) / VEHICLE_MAX_SPEED);
+                car->steer = zpl_clamp(car->steer, -40.0f, 40.0f);
             }
         }
     }
@@ -242,7 +269,7 @@ void SystemsImport(ecs_world_t *ecs) {
     ECS_SYSTEM(ecs, DemoNPCMoveAround, EcsOnLoad, components.Velocity, components.EcsDemoNPC);
     ECS_SYSTEM(ecs, EnterOrLeaveVehicle, EcsOnLoad, components.Input, components.Position);
     
-    ECS_SYSTEM(ecs, MoveWalk, EcsOnUpdate, components.Position, components.Velocity);
+    ECS_SYSTEM(ecs, MoveWalk, EcsOnUpdate, components.Position, components.Velocity, !components.Vehicle);
     ECS_SYSTEM(ecs, HurtOnHazardBlock, EcsOnUpdate, components.Position, components.Health);
     ECS_SYSTEM(ecs, RegenerateHP, EcsOnUpdate, components.Health);
     ECS_SYSTEM(ecs, VehicleHandling, EcsOnUpdate, components.Vehicle, components.Position, components.Velocity);