Engine::Physics Struct Reference

#include <Physics.hpp>

Public Types
enum	CollisionType { D2, D3 }

Static Public Member Functions
static std::vector< CollisionPoint >	Raycast (const Scene &scene, glm::vec3 pos, glm::vec3 dir, float maxDistance=FLT_MAX)
static CollisionPoint	RaycastClosest (const Scene &scene, glm::vec3 pos, glm::vec3 dir, float maxDistance=FLT_MAX)
static CollisionPoint	GJK_EPA (const Shape &colliderA, const Shape &colliderB, CollisionType type=D3)
	Combination Gilbert-Johnson-Keerthi Expanding-Polytope-Algorithm TODO: (not fully memory optimized)
static CollisionPoint	EPA2 (Simplex &simplex, const Shape &shapeA, const Shape &shapeB)
	Expanding Polytope Algorithm Implementation Calculates the separation normal from a colliding GJK simplex. Assumes that the input simplex contains a collision. More...
static bool	GJK (const Shape &colliderA, const Shape &colliderB, Simplex &simplex, CollisionType type)
	Gilbert-Johnson-Keerthi collision detection algorithm https://blog.winter.dev/2020/gjk-algorithm/ improved from. More...
static bool	NextSimplex (Simplex &simplex, glm::vec3 &direction, CollisionType type)
static bool	Line (Simplex &simplex, glm::vec3 &direction)
static bool	Triangle (Simplex &simplex, glm::vec3 &direction)
static bool	Tetrahedron (Simplex &simplex, glm::vec3 &direction)
static void	Update (Scene &scene)
static void	simulateSystem (Scene &scene, float dt)
	Simulate the scene elements by a delta t Partially Implements Extended Position Based Dynamics. More...
static CollisionPoint	processJoint (const Ref< Joint > &joint, const Ref< PhysicsEntity > &pe1, const Ref< PhysicsEntity > &pe2)
static void	processJoints (const std::vector< Ref< Joint >> &joints, float h)
static void	processCollisions (std::vector< Ref< PhysicsEntity >> &elements, float h, CollisionType type=D3)
	Generate collision data and solve it. More...
static void	applyManifold (CollisionPoint cp, Ref< PhysicsEntity > &e1, Ref< PhysicsEntity > &e2, float h)
static std::vector< Ref< Joint > >	CollectJoints (const Scene &scene)
static std::vector< Ref< PhysicsEntity > >	CollectBodiesAndParticles (Scene &scene)
static std::vector< Ref< PhysicsEntity > >	Collect2DElements (Scene &scene)
static Support	furthestDiff (const Shape &shapeA, const Shape &shapeB, const glm::vec3 &norm, Support &support)
static void	Barycentric (const glm::vec3 &p, const glm::vec3 &a, const glm::vec3 &b, const glm::vec3 &c, float &u, float &v, float &w)

Detailed Description

XPBD GJK EPA style physics engine (enjoy :) ).

Member Enumeration Documentation

CollisionType

enum Engine::Physics::CollisionType

Enumeration for indexing 3D or 2D physics interactions.

Member Function Documentation

applyManifold()

static void Engine::Physics::applyManifold ( CollisionPoint  cp, Ref< PhysicsEntity > &  e1, Ref< PhysicsEntity > &  e2, float  h  )

inlinestatic

Process delta x and delta q data from joints or collisions.

Parameters

cp	delta data
e1	physics entity 1
e2	physics entitiy 2
h	delta t

Barycentric()

static void Engine::Physics::Barycentric ( const glm::vec3 &  p, const glm::vec3 &  a, const glm::vec3 &  b, const glm::vec3 &  c, float &  u, float &  v, float &  w  )

inlinestatic

Calculate barycentric coordinates.

lovingly adapted from https://gamedev.stackexchange.com/questions/23743/whats-the-most-efficient-way-to-find-barycentric-coordinates

Inputs are the collision point the face vertexes and the outputs are the triangle coordinates (u, v, w).

Parameters

p
a
b
c
u
v
w

Collect2DElements()

static std::vector<Ref<PhysicsEntity> > Engine::Physics::Collect2DElements ( Scene &  scene )

inlinestatic

Generate a list of 2D PhysicsEntity from the scene.

Parameters

scene

reference

Returns

list of PhysicsEntity

CollectBodiesAndParticles()

static std::vector<Ref<PhysicsEntity> > Engine::Physics::CollectBodiesAndParticles ( Scene &  scene )

inlinestatic

Generate a list of PhysicsEntity from the scene.

Parameters

scene

reference

Returns

list of PhysicsEntity

CollectJoints()

static std::vector<Ref<Joint> > Engine::Physics::CollectJoints ( const Scene &  scene )

inlinestatic

Collect joint Components from the Scene.

Parameters

scene

scene reference.

Returns

list of Joints

EPA2()

static CollisionPoint Engine::Physics::EPA2 ( Simplex &  simplex, const Shape &  shapeA, const Shape &  shapeB  )

inlinestatic

Expanding Polytope Algorithm Implementation Calculates the separation normal from a colliding GJK simplex. Assumes that the input simplex contains a collision.

lovingly adapted from https://github.com/kevinmoran/GJK/blob/master/GJK.h

Parameters

simplex	output from running GJK
shapeA	shape definition for object A
shapeB	shape definition for object B

Returns

struct containing collision data (always returns a collision normal)

furthestDiff()

static Support Engine::Physics::furthestDiff ( const Shape &  shapeA, const Shape &  shapeB, const glm::vec3 &  norm, Support &  support  )

inlinestatic

Find the difference vector between the two furthest vertex points in the two shapes along the normal.

Parameters

shapeA
shapeB
norm
support	storage for the support points

Returns

the support point

GJK()

static bool Engine::Physics::GJK ( const Shape &  colliderA, const Shape &  colliderB, Simplex &  simplex, CollisionType  type  )

inlinestatic

Gilbert-Johnson-Keerthi collision detection algorithm https://blog.winter.dev/2020/gjk-algorithm/ improved from.

Parameters

colliderA	shape definition for object A
colliderB	shape definition for object B
simplex	storage for simplex data

Returns

true if a there is a collision, false otherwise.

processCollisions()

static void Engine::Physics::processCollisions ( std::vector< Ref< PhysicsEntity >> &  elements, float  h, CollisionType  type = D3  )

inlinestatic

Generate collision data and solve it.

Using GKJ and EPA produce collision normals and then solve them using XPBD.

Parameters

elements	list of physics elements
h	delta t
type	type of collisions to produce (for 2D the physics are not calculated)

processJoint()

static CollisionPoint Engine::Physics::processJoint ( const Ref< Joint > &  joint, const Ref< PhysicsEntity > &  pe1, const Ref< PhysicsEntity > &  pe2  )

inlinestatic

Process a Joint structure using physics entity data.

Parameters

joint
pe1
pe2

Returns

A collision point representing any deltas to solve.

processJoints()

static void Engine::Physics::processJoints ( const std::vector< Ref< Joint >> &  joints, float  h  )

inlinestatic

Generate Joint collision interactions.

Parameters

joints	list of joints
h	delta t

Raycast()

static std::vector<CollisionPoint> Engine::Physics::Raycast ( const Scene &  scene, glm::vec3  pos, glm::vec3  dir, float  maxDistance = FLT_MAX  )

inlinestatic

Unimplemented raycasting function. TODO: Implement and test

Parameters

scene
pos
dir
maxDistance

Returns

RaycastClosest()

static CollisionPoint Engine::Physics::RaycastClosest ( const Scene &  scene, glm::vec3  pos, glm::vec3  dir, float  maxDistance = FLT_MAX  )

inlinestatic

Another unimplemented Raycasting function. TODO: Implement and test

Parameters

scene
pos
dir
maxDistance

Returns

simulateSystem()

static void Engine::Physics::simulateSystem ( Scene &  scene, float  dt  )

inlinestatic

Simulate the scene elements by a delta t Partially Implements Extended Position Based Dynamics.

Collects PhysicsEntities from the scene. Calculates their interactions. Produces delta values. And updates the corresponding scene components.

Parameters

scene	scene reference
dt	time delta

Update()

static void Engine::Physics::Update ( Scene &  scene )

inlinestatic

Update the physics parameters of the scene.

Parameters

scene

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The documentation for this struct was generated from the following file:

• include/Physics.hpp