MathC is a simple math library for 2D and 3D programming. It contains implementations for:

• 2D vectors
• 3D vectors
• Quaternions
• Matrices
• Easing functions

It support C99 standard or later.

The reference is the file REFERENCE.md.

Every structure and function uses float, because it is the most used type on 2D and 3D programming with OpenGL.

The type float loses precision with large numbers, why not use double? Because every double value would be converted to float before sending to OpenGL, anyway. Which means your physics would run with high precision, but the rendering would still be affected by the float imprecision. Instead, the good practice to solve the problem with large numbers is to truncate the world position back to [0.0f, 0.0f, 0.0f] when the world distance to the center is too large. If the world is too big that even when truncating there is stil large numbers, the correct approach is to divide the world in chunks.

For every function that takes a structure, there are two versions. One that you pass structures as value and other that you pass as pointer. The functions that pass the value by pointer have a prefix p before the type name (pvector2, pvector3, pquaternion and pmatrix) and the result is the *result argument or a returned float.

You can decide which one you want to use.

Examples:

/* Pass by value and return a value */
struct mat projection = matrix_ortho(-100.0f, 100.0f, -100.0f, 100.0f, 0.0f, 1.0f);
struct mat view = matrix_look_at(to_vector3(0.0f, 0.0f, 1.0f),
	to_vector3(0.0f, 0.0f, 0.0f),
	to_vector3(0.0f, 1.0f, 0.0f));
struct mat pv = matrix_multiply_matrix(projection, view);

/* Pass by pointer */
struct vec pos = {0};
struct vec target = {0};
struct vec up = {0};
struct mat projection;
struct mat view;
struct mat multiplied_matrix;

to_pvector3(0.0f, 0.0f, 1.0f, &pos);
to_pvector3(0.0f, 0.0f, 0.0f, &target);
to_pvector3(0.0f, 1.0f, 0.0f, &up);
pmatrix_ortho(-100.0f, 100.0f, -100.0f, 100.0f, 0.0f, 1.0f, &projection);
pmatrix_look_at(&pos, &target, &up, &view);
pmatrix_multiply_matrix(&projection, &view, &multiplied_matrix);

All vectors (2D, 3D and quaternions ) use the same structure type struct vec.

Examples:

/* Rotate a 2D vector 90º */
struct vec direction = to_vector2(0.0f, -1.0f);
direction = vector2_rotate(90.0f * M_PIF / 180.0f);

/* Get the angle (radians) of a 2D vector */
float angle = vector2_angle(direction);

/* Create a 3D vector */
struct vec position = to_vector3(0.0f, 0.0f, 0.0f);

/* Create a quaternion */
struct vec quaternion = to_quaternion(0.0f, 0.0f, 0.0f, 1.0f);
/* Spherical interpolation between two quaternions */
struct vec interpolated = quaternion_spherical_linear_interpolation(a, b, 0.5f);

All matrices are 4×4. There are functions for setting up projection matrices, view matrices and model matrices.

Usually, model matrices are used to modify vertices on client-side or GPU-side. If you want to modify on client-side, you can use the functions matrix_multiply_f4() or pmatrix_multiply_f4() to modify an array with 4 float elements. Example:

float v[4] = {0.0f, 10.0f, 0.0f, 1.0f}; /* Compoments X, Y, Z and W */
struct mat rotation = matrix_rotation_z(to_radians(45.0f));
matrix_multiply_f4(rotation, v);

If you want to modify on GPU-side, you can use the functions matrix_to_array() or pmatrix_to_array() to push the matrix to an array with 16 float elements. Example:

float v[16];
struct mat projection = matrix_ortho(-100.0f, 100.0f, -100.0f, 100.0f, 0.0f, 1.0f);
struct mat view = matrix_look_at(to_vector3(0.0f, 0.0f, 1.0f),
	to_vector3(0.0f, 0.0f, 0.0f),
	to_vector3(0.0f, 1.0f, 0.0f));
struct mat pv = matrix_multiply_matrix(projection, view);
matrix_to_array(pv, v);

The easing functions are an implementation of the functions presented in easing.net. They are mainly useful for animations.

Easing functions take a value that range from 0.0f to 1.0f and usually will return a value inside that same range. However, in some of the easing functions, the returned value extrapolate that range.

• Before sending any pull request, open an issue asking if the feature or fix is already being worked on.
• If you find any error, you can open an issue.
• You can request more useful functions in the issues regarding 2D vectors, 3D vectors, quaternions and matrices. If you have already an implementation or know where to find, better.
• Everything here will stay licensed under ZLIB, which is a very permissive license.

The source code of this project is licensed under the terms of the ZLIB license:

Copyright (C) 2016 Felipe Ferreira da Silva

This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.

Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.