A single-file 2D collision library written in C.
The goal with this library is to create a straightforward library that checks for collisions and calculates overlaps for a wide variety of 2 dimensional shapes and lines (and doesn't try to do anything else). It should be clear from the code and the comments what each function is doing. There are no dependencies aside from math.h.
SIMPLE_COLLISION_2D_IMPLEMENTATION should be defined in one C/C++ source file before including this header. It can then be included in any other source file that references its functions like a standard header.
The sc2d functions all follow a similar structure and all return true if a collision has occurred.
bool sc2d_check_shape1_shape2(
[in] float p1x,
[in] float p1y,
[in] float shape1_dimensions ... ,
[in] float p2x,
[in] float p2y,
[in] float shape2_dimensions ... ,
[out] float *overlap_x,
[out] float *overlap_y,
)| Argument | Description |
|---|---|
| p1x, p1y | Position of first shape |
width, height radius *vertices, vert_count |
Dimensions of first shape: Rectangle Circle Polygon |
| p2x, p2y | Position of second shape |
width, height radius *vertices, vert_count |
Dimensions of second shape: Rectangle Circle Polygon |
| overlap_x, overlap_y | Value of shortest overlap (or intersection)** |
The overlap vector is always relative to the first shape in the argument list. Therefore, for static resolution it should be subtracted from the position of shape1 and/or added to position shape2 to push the shapes apart.
if (sc2d_check_circles(p1.x, p1.y, r1, p2.x, p2.y, r2, &overlap.x, &overlap.y)) {
p1.x -= overlap.x / 2.0f;
p1.y -= overlap.y / 2.0f;
p2.x += overlap.x / 2.0f;
p2.y += overlap.y / 2.0f;
}By default, the polygon collision functions sc2d_check_poly2d and sc2d_check_point_poly2d assume vertices are defined as float x/y pairs. To use these functions with a different type, you can define a custom sc2d_v2 struct type with members x and y before the implementation as follows:
#ifndef SIMPLE_COLLISION_2D_VECTOR2
typedef Vector3 sc2d_v2;
#define SIMPLE_COLLISION_2D_VECTOR2
#endif
#define SIMPLE_COLLISION_2D_IMPLEMENTATION
#include "sc2d.h"The demo project uses Vector3 in this way (z is ignored) to demonstrate this. This may or may not be a good idea.
The included demo program currently uses raylib version 4.0.0 or later, but doesn't make extensive use of its features. Set sc2d_RAYLIB_DIR in src/demo/CMakeLists.txt to a raylib source directory on your machine.
Also included is a build/run configuration for Windows.
config.bat
build.bat
run.bat
This assumes that you have MinGW and Ninja installed.