From 6c43a7cdc5c8e95520cc992c6584f565b8e7fdd3 Mon Sep 17 00:00:00 2001
From: Imbris <imbrisf@gmail.com>
Date: Sat, 19 Sep 2020 19:35:14 -0400
Subject: [PATCH] Change projectiles to not be pushed back by collisions, moved
 group check into projectile system from physics system

---
 common/src/sys/phys.rs       | 31 ++++++++++---------------------
 common/src/sys/projectile.rs | 22 +++++++++++++++++++++-
 2 files changed, 31 insertions(+), 22 deletions(-)

diff --git a/common/src/sys/phys.rs b/common/src/sys/phys.rs
index a2b5947b6e..b06f329b9e 100644
--- a/common/src/sys/phys.rs
+++ b/common/src/sys/phys.rs
@@ -1,21 +1,18 @@
 use crate::{
     comp::{
-        BeamSegment, Collider, Gravity, Group, Mass, Mounting, Ori, PhysicsState, Pos, Projectile,
-        Scale, Sticky, Vel,
+        BeamSegment, Collider, Gravity, Mass, Mounting, Ori, PhysicsState, Pos, Projectile, Scale,
+        Sticky, Vel,
     },
     event::{EventBus, ServerEvent},
     metrics::SysMetrics,
     span,
     state::DeltaTime,
-    sync::{Uid, UidAllocator},
+    sync::Uid,
     terrain::{Block, TerrainGrid},
     vol::ReadVol,
 };
 use rayon::iter::ParallelIterator;
-use specs::{
-    saveload::MarkerAllocator, Entities, Join, ParJoin, Read, ReadExpect, ReadStorage, System,
-    WriteStorage,
-};
+use specs::{Entities, Join, ParJoin, Read, ReadExpect, ReadStorage, System, WriteStorage};
 use std::ops::Range;
 use vek::*;
 
@@ -55,7 +52,6 @@ impl<'a> System<'a> for Sys {
         ReadStorage<'a, Uid>,
         ReadExpect<'a, TerrainGrid>,
         Read<'a, DeltaTime>,
-        Read<'a, UidAllocator>,
         ReadExpect<'a, SysMetrics>,
         Read<'a, EventBus<ServerEvent>>,
         ReadStorage<'a, Scale>,
@@ -68,7 +64,6 @@ impl<'a> System<'a> for Sys {
         WriteStorage<'a, Vel>,
         WriteStorage<'a, Ori>,
         ReadStorage<'a, Mounting>,
-        ReadStorage<'a, Group>,
         ReadStorage<'a, Projectile>,
         ReadStorage<'a, BeamSegment>,
     );
@@ -82,7 +77,6 @@ impl<'a> System<'a> for Sys {
             uids,
             terrain,
             dt,
-            uid_allocator,
             sys_metrics,
             event_bus,
             scales,
@@ -95,7 +89,6 @@ impl<'a> System<'a> for Sys {
             mut velocities,
             mut orientations,
             mountings,
-            groups,
             projectiles,
             beams,
         ): Self::SystemData,
@@ -161,12 +154,7 @@ impl<'a> System<'a> for Sys {
             // Resets touch_entities in physics
             physics.touch_entities.clear();
 
-            // Group to ignore collisions with
-            let ignore_group = projectile
-                .filter(|p| p.ignore_group)
-                .and_then(|p| p.owner)
-                .and_then(|uid| uid_allocator.retrieve_entity_internal(uid.into()))
-                .and_then(|e| groups.get(e));
+            let is_projectile = projectile.is_some();
 
             let mut vel_delta = Vec3::zero();
 
@@ -178,7 +166,7 @@ impl<'a> System<'a> for Sys {
                 mass_other,
                 collider_other,
                 _,
-                group_b,
+                _,
                 _,
             ) in (
                 &entities,
@@ -187,13 +175,13 @@ impl<'a> System<'a> for Sys {
                 scales.maybe(),
                 masses.maybe(),
                 colliders.maybe(),
+                !&projectiles,
                 !&mountings,
-                groups.maybe(),
                 !&beams,
             )
                 .join()
             {
-                if entity == entity_other || (ignore_group.is_some() && ignore_group == group_b) {
+                if entity == entity_other {
                     continue;
                 }
 
@@ -244,7 +232,8 @@ impl<'a> System<'a> for Sys {
                             physics.touch_entities.push(*other);
                         }
 
-                        if diff.magnitude_squared() > 0.0 {
+                        // Don't apply repulsive force to projectiles
+                        if diff.magnitude_squared() > 0.0 && !is_projectile {
                             let force = 400.0 * (collision_dist - diff.magnitude()) * mass_other
                                 / (mass + mass_other);
 
diff --git a/common/src/sys/projectile.rs b/common/src/sys/projectile.rs
index e9677c2394..ba7ece43d1 100644
--- a/common/src/sys/projectile.rs
+++ b/common/src/sys/projectile.rs
@@ -1,6 +1,6 @@
 use crate::{
     comp::{
-        projectile, Damage, DamageSource, Energy, EnergySource, HealthChange, HealthSource,
+        projectile, Damage, DamageSource, Energy, EnergySource, HealthChange, HealthSource, Group,
         Loadout, Ori, PhysicsState, Pos, Projectile, Vel,
     },
     event::{EventBus, LocalEvent, ServerEvent},
@@ -34,6 +34,7 @@ impl<'a> System<'a> for Sys {
         WriteStorage<'a, Projectile>,
         WriteStorage<'a, Energy>,
         ReadStorage<'a, Loadout>,
+        ReadStorage<'a, Group>,
     );
 
     fn run(
@@ -52,6 +53,7 @@ impl<'a> System<'a> for Sys {
             mut projectiles,
             mut energies,
             loadouts,
+            groups,
         ): Self::SystemData,
     ) {
         let start_time = std::time::Instant::now();
@@ -71,6 +73,24 @@ impl<'a> System<'a> for Sys {
         {
             // Hit entity
             for other in physics.touch_entities.iter().copied() {
+                if projectile.ignore_group
+                    // Skip if in the same group
+                    && projectile
+                        .owner
+                        // Note: somewhat inefficient since we do the lookup for every touching
+                        // entity, but if we pull this out of the loop we would want to do it only
+                        // if there is at least one touching entity
+                        .and_then(|uid| uid_allocator.retrieve_entity_internal(uid.into()))
+                        .and_then(|e| groups.get(e))
+                        .map_or(false, |owner_group| 
+                            Some(owner_group) == uid_allocator
+                            .retrieve_entity_internal(other.into())
+                            .and_then(|e| groups.get(e))
+                        )
+                {
+                    continue;
+                }
+
                 if projectile.owner == Some(other) {
                     continue;
                 }