sgjk is a simple implementation of the Gilbert–Johnson–Keerthi (GJK) algorithm. It supports C++11 and higher versions.
- No STD Dependencies(optional): sgjk can work without any standard library dependencies if you choose to redefine specific macros.
- Custom Classes: It supports user-defined vector, collider, and transform classes that meet modest requirements.
- Collision Detection and Resolution: sgjk can detect and resolve collisions in both 2D and 3D spaces.
The term "simple" is an ABSOLUTE LIE. This "simple" implementation has destroyed me from within. I tried to provide all possible ways to customize classes but forgot that in C++, you can customize EVERYTHING. Freedom of choice is the enemy of any programmer.
While working on this project, I learned to suffer and do it with a smile. In reality, I learned a lot.
To use SGJK in your project, simply include the sgjk_head.hpp header file in your source code. Additionally, you can customize various aspects of the library by defining specific macros before including the header.
#include "sgjk_head.hpp"SGJK allows you to customize various aspects of the library by defining specific macros before including the header. This can help you avoid dependencies and tailor the library to your specific needs.
By default, SGJK uses the standard assert macro for assertions. You can override this by defining the SGJK_ASSERT macro before including the header.
#define SGJK_ASSERT(expr__) your_custom_assert(expr__)SGJK uses std::vector as the default container. You can override this by defining the SGJK_DEFAULT_CONTAINER macro before including the header.
#define SGJK_DEFAULT_CONTAINER your_custom_containerjust define a macros.
SGJK provides a vec2T and vec3T template class for 2D and 3D vectors, respectively. These classes support various mathematical operations such as addition, subtraction, dot product, cross product, and normalization.
sgjk::linear::vec2 v1(1.0f, 2.0f);
sgjk::linear::vec2 v2(3.0f, 4.0f);
sgjk::linear::vec2 v3 = v1 + v2;
float dotProduct = sgjk::linear::dot(v1, v2);SGJK provides predefined colliders for polygons, circles and wapper for any collider type. You can also define your own custom colliders by implementing the required methods.
Collider classes must implement an interface with the following methods:
- get_some_point: This method should return any point on the surface of the collider, taking into account any applied transformations.
- get_furthest_point: This method should find and return the furthest point in a given direction, taking into account any applied transformations.
std::vector<sgjk::linear::vec2> vertices = {
sgjk::linear::vec2(0.0f, 0.0f),
sgjk::linear::vec2(1.0f, 0.0f),
sgjk::linear::vec2(1.0f, 1.0f),
sgjk::linear::vec2(0.0f, 1.0f)
};
sgjk::polygon_collider_2d polygonCollider(vertices);sgjk::linear::vec2 center(0.0f, 0.0f);
float radius = 1.0f;
sgjk::circle_collider_2d circleCollider(center, radius);std::vector<sgjk::linear::vec2> vertices = {
sgjk::linear::vec2(0.0f, 0.0f),
sgjk::linear::vec2(1.0f, 0.0f),
sgjk::linear::vec2(1.0f, 1.0f)
};
sgjk::polygon_collider_2d polygonCollider(vertices);
sgjk::linear::vec2 center(0.0f, 0.0f);
float radius = 1.0f;
sgjk::circle_collider_2d circleCollider(center, radius);
sgjk::collider_wrapper_2d wrapper;
wrapper = circleCollider;
wrapper = polygonCollider;sgjk provides a flexible transform system that allows you to define and use custom transformations for your vectors. The transform system includes support for both 2D and 3D transformations, as well as a generic wrapper for any type of transformation.
Transform classes must implement an interface with the following methods:
- transformed: method that takes a vector of the corresponding type as input and returns a transformed vector. This method should apply the transformation to the input vector and return the result.
The transform_wrapper_anydt template class allows you to wrap any transformation class that meets certain requirements. This wrapper provides a unified interface for applying transformations to vectors.
The empty_transform template class provides a default transformation that does not modify the input vector.
The transform_2dt template class provides a 2D transformation that includes translation and rotation.
The transform_3dt template class provides a 3D transformation that includes translation and rotation around multiple axes.
SGJK provides collision detectors for 2D and 3D spaces. You can use these detectors to check for collisions between two colliders.
sgjk::collision_detecter_2d collisionDetector;
bool isColliding = collisionDetector.is_collide(polygonCollider, circleCollider);#include "sgjk_head.hpp"
#include <iostream>
int main() {
const std::vector<sgjk::linear::vec2> vertices1{
sgjk::linear::vec2(0.0f, 0.0f),
sgjk::linear::vec2(1.0f, 0.0f),
sgjk::linear::vec2(1.0f, 1.0f),
sgjk::linear::vec2(0.0f, 1.0f)
};
const std::vector<sgjk::linear::vec2> vertices2{
sgjk::linear::vec2(2.0f, 2.0f),
sgjk::linear::vec2(3.0f, 2.0f),
sgjk::linear::vec2(3.0f, 3.0f),
sgjk::linear::vec2(2.0f, 3.0f)
};
sgjk::polygon_collider_2d collider1(vertices1);
sgjk::polygon_collider_2d collider2(vertices2);
sgjk::collision_detecter_2d collisionDetector;
if (collisionDetector.is_collide(collider1, collider2)) {
std::cout << "Shapes intersect\n";
} else {
std::cout << "Shapes do not intersect\n";
}
return 0;
}#include "sgjk_head.hpp"
#include <iostream>
int main() {
const std::vector<sgjk::linear::vec3> vertices1{
sgjk::linear::vec2(0.0f, 0.0f, 0.0f),
sgjk::linear::vec2(1.0f, 0.0f, 0.0f),
sgjk::linear::vec2(1.0f, 1.0f, 0.0f),
sgjk::linear::vec2(0.0f, 1.0f, 0.0f),
sgjk::linear::vec2(0.0f, 0.0f, 1.0f),
sgjk::linear::vec2(1.0f, 0.0f, 1.0f),
sgjk::linear::vec2(1.0f, 1.0f, 1.0f),
sgjk::linear::vec2(0.0f, 1.0f, 1.0f)
};
sgjk::polygon_collider_3d collider1(vertices1);
sgjk::linear::vec3 center(0.0f);
float radius = 1.0f;
sgjk::circle_collider_3d collider2(center, radius);
sgjk::collision_detecter_3d collisionDetector;
if (collisionDetector.is_collide(collider1, collider2)) {
std::cout << "Shapes intersect\n";
} else {
std::cout << "Shapes do not intersect\n";
}
return 0;
}SGJK is released under the MIT License. See the LICENSE file for more information.
SGJK is inspired by the GJK algorithm and various implementations of collision detection libraries. Special thanks to the authors of these algorithms.