From 93e34b2c88fd3dbc7f6d8509d7a04d33c48ce512 Mon Sep 17 00:00:00 2001
From: griffi-gh <prasol258@gmail.com>
Date: Wed, 14 Feb 2024 21:56:59 +0100
Subject: [PATCH] refactor stuff

---
 kubi/src/client_physics.rs | 86 ++++++++++++++++++++++++++------------
 1 file changed, 59 insertions(+), 27 deletions(-)

diff --git a/kubi/src/client_physics.rs b/kubi/src/client_physics.rs
index 17bcb7b..7bb2aad 100644
--- a/kubi/src/client_physics.rs
+++ b/kubi/src/client_physics.rs
@@ -8,8 +8,21 @@ use crate::{delta_time::DeltaTime, world::ChunkStorage};
 #[derive(Unique)]
 pub struct GlobalClPhysicsConfig {
   pub gravity: Vec3,
+  ///XXX: currenly unused:
+  pub iterations: usize,
 }
 
+impl Default for GlobalClPhysicsConfig {
+  fn default() -> Self {
+    Self {
+      gravity: Vec3::new(0., -9.8, 0.),
+      iterations: 10,
+    }
+  }
+}
+
+//TODO: actors should be represented by a vertical line, not a point.
+//XXX: maybe a capsule? (or configurable hull?)
 #[derive(Component)]
 pub struct ClPhysicsActor {
   pub offset: Vec3,
@@ -18,7 +31,8 @@ pub struct ClPhysicsActor {
   pub terminal_velocity: f32,
   //TODO: this should be configurable per block
   pub friction_agains_ground: f32,
-  on_ground_flag: bool,
+  flag_ground: bool,
+  flag_collision: bool,
 }
 
 impl ClPhysicsActor {
@@ -27,7 +41,7 @@ impl ClPhysicsActor {
   }
 
   pub fn on_ground(&self) -> bool {
-    self.on_ground_flag
+    self.flag_ground
   }
 }
 
@@ -40,73 +54,91 @@ impl Default for ClPhysicsActor {
       velocity: Vec3::ZERO,
       terminal_velocity: 40.,
       friction_agains_ground: 0.5,
-      on_ground_flag: false,
+      flag_ground: false,
+      flag_collision: false,
     }
   }
 }
 
+trait BlockCollisionExt {
+  fn collision_type(&self) -> CollisionType;
+  fn is_solid(&self) -> bool {
+    self.collision_type() == CollisionType::Solid
+  }
+}
+
+impl BlockCollisionExt for Option<Block> {
+  fn collision_type(&self) -> CollisionType {
+    self.unwrap_or(Block::Air).descriptor().collision
+  }
+}
+
+impl BlockCollisionExt for Block {
+  fn collision_type(&self) -> CollisionType {
+    self.descriptor().collision
+  }
+}
+
 pub fn init_client_physics(
   storages: AllStoragesView,
 ) {
-  storages.add_unique(GlobalClPhysicsConfig {
-    gravity: Vec3::new(0., -1.0, 0.),
-  });
+  storages.add_unique(GlobalClPhysicsConfig::default());
 }
 
 pub fn update_client_physics_late(
   mut actors: ViewMut<ClPhysicsActor>,
   mut transforms: ViewMut<Transform, track::All>,
-  phy_conf: UniqueView<GlobalClPhysicsConfig>,
+  conf: UniqueView<GlobalClPhysicsConfig>,
   world: UniqueView<ChunkStorage>,
   dt: UniqueView<DeltaTime>,
 ) {
   for (mut actor, mut transform) in (&mut actors, &mut transforms).iter() {
     //apply forces
     let actor_forces = actor.forces;
-    actor.velocity += actor_forces + phy_conf.gravity;
+    actor.velocity += (actor_forces + conf.gravity) * dt.0.as_secs_f32();
     actor.forces = Vec3::ZERO;
 
+    //get position
     let (scale, rotation, mut actor_position) = transform.0.to_scale_rotation_translation();
     actor_position -= actor.offset;
+
+    //get grid-aligned pos and blocks
     let actor_block_pos = actor_position.floor().as_ivec3();
     let actor_block = world.get_block(actor_block_pos);
     let actor_block_below = world.get_block(actor_block_pos + IVec3::NEG_Y);
-    actor.on_ground_flag =
-      actor_block_below.map_or_else(|| false, |x| x.descriptor().collision == CollisionType::Solid) ||
-      actor_block.map_or_else(|| false, |x| x.descriptor().collision == CollisionType::Solid);
+
+    //update flags
+    actor.flag_collision = actor_block.is_solid();
+    actor.flag_ground = actor.flag_collision || actor_block_below.is_solid();
+
     //push actor back out of the block
-    if actor_block.is_some() {
-      //first, compute the normal (assuming actor is a point)
-      //must be accurate!
-      let mut normal = Vec3::ZERO;
-      for i in 0..3 {
-        let mut offset = Vec3::ZERO;
-        offset[i] = 0.5;
-        let block_pos = actor_block_pos + offset.as_ivec3();
-        let block = world.get_block(block_pos).unwrap_or(Block::Air);
-        if block.descriptor().collision == CollisionType::Solid {
-          normal[i] = 1.;
-        }
-      }
+    if actor.flag_collision {
+      //first, compute restitution, based on position inside the block
+      // let block_center = actor_block_pos.as_f32() + Vec3::ONE * 0.5;
+      // let to_block_center = actor_position - block_center;
+
       //then, based on normal:
       //push the actor back
-      actor_position += normal * 0.5;
+      //actor_position += normal * 0.5;
       //cancel out velocity in the direction of the normal
       // let dot = actor.velocity.dot(normal);
       // if dot > 0. {
       //   //actor.velocity -= normal * dot;
       //   actor.velocity = Vec3::ZERO;
       // }
-      if actor.on_ground_flag {
+
+      //HACK: for now, just stop the vertical velocity if on ground altogether,
+      //as we don't have proper collision velocity resolution yet (we need to compute dot product or sth)
+      if actor.flag_ground {
         actor.velocity.y = 0.;
       }
     }
+
     //Apply velocity
     actor_position += actor.velocity * dt.0.as_secs_f32();
     actor_position += actor.offset;
     transform.0 = Mat4::from_scale_rotation_translation(scale, rotation, actor_position);
   }
-
   // for (_, mut transform) in (&controllers, &mut transforms).iter() {
   //   let (scale, rotation, mut translation) = transform.0.to_scale_rotation_translation();
   //   translation.y -= dt.0.as_secs_f32() * 100.;