1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101

// Copyright 2016-2018 Matthew D. Michelotti
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Collider is a library for continuous 2D collision detection,
//! for use with game developement.
//!
//! Most game engines follow the approach of periodically updating the
//! positions of all shapes and checking for collisions at a frozen snapshot in time.
//! [Continuous collision detection](https://en.wikipedia.org/wiki/Collision_detection#A_posteriori_.28discrete.29_versus_a_priori_.28continuous.29),
//! on the other hand, means that the time of collision is determined very precisely,
//! and the user is not restricted to a fixed time-stepping method.
//! There are currently two kinds of shapes supported by Collider: circles and rectangles.
//! The user specifies the positions and velocities of these shapes, which
//! they can update at any time, and Collider will solve for the precise times of
//! collision and separation.
//!
//! There are certain advantages that continuous collision detection
//! holds over the traditional approach.
//! In a game engine, the position of a sprite may be updated to overlap a wall,
//! and in a traditional collision system there would need to be a post-correction
//! to make sure the sprite does not appear inside of the wall.
//! This is not needed with continuous collision detection, since
//! the precise time and location at which the sprite touches the wall is known.
//! Traditional collision detection may have an issue with "tunneling," in which a
//! fast small object runs into a narrow wall and collision detection misses it,
//! or two fast small objects fly right through each other and collision detection misses it.
//! This is also not a problem for continuous collision detection.
//! It is also debatable that continuous collision detection may be
//! more efficient in certain circumstances,
//! since the hitboxes may be updated less frequently and still maintain a
//! smooth appearance over time.
//!
//! #Example
//! ```
//! use collider::{Collider, HbEvent, HbId, HbProfile};
//! use collider::geom::{Shape, v2};
//!
//! #[derive(Copy, Clone, Debug)]
//! struct DemoHbProfile { id: HbId } // add any additional identfying data to this struct
//!
//! impl HbProfile for DemoHbProfile {
//!     fn id(&self) -> HbId { self.id }
//!     fn can_interact(&self, _other: &DemoHbProfile) -> bool { true }
//!     fn cell_width() -> f64 { 4.0 }
//!     fn padding() -> f64 { 0.01 }
//! }
//!
//! let mut collider: Collider<DemoHbProfile> = Collider::new();
//!
//! let hitbox = Shape::square(2.0).place(v2(-10.0, 0.0)).moving(v2(1.0, 0.0));
//! let overlaps = collider.add_hitbox(DemoHbProfile { id: 0 }, hitbox);
//! assert!(overlaps.is_empty());
//!
//! let hitbox = Shape::square(2.0).place(v2(10.0, 0.0)).moving(v2(-1.0, 0.0));
//! let overlaps = collider.add_hitbox(DemoHbProfile { id: 1 }, hitbox);
//! assert!(overlaps.is_empty());
//!
//! while collider.time() < 20.0 {
//!     let time = collider.next_time().min(20.0);
//!     collider.set_time(time);
//!     if let Some((event, profile_1, profile_2)) = collider.next() {
//!         println!("{:?} between {:?} and {:?} at time {}.",
//!                  event, profile_1, profile_2, collider.time());
//!         if event == HbEvent::Collide {
//!             println!("Speed of collided hitboxes is halved.");
//!             for profile in [profile_1, profile_2].iter() {
//!                 let mut hb_vel = collider.get_hitbox(profile.id()).vel;
//!                 hb_vel.value *= 0.5;
//!                 collider.set_hitbox_vel(profile.id(), hb_vel);
//!             }
//!         }
//!     }
//! }
//!
//! // the above loop prints the following events:
//! //   Collide between DemoHbProfile { id: 0 } and DemoHbProfile { id: 1 } at time 9.
//! //   Speed of collided hitboxes is halved.
//! //   Separate between DemoHbProfile { id: 0 } and DemoHbProfile { id: 1 } at time 13.01.
//! ```

extern crate fnv;

mod float;
pub mod geom;
mod util;
mod core;
mod index_rect;
#[cfg(test)] mod tests;

pub use core::*;