# Basic Geomtric Computations

[Русская версия / Russian version](intro-rus.md)

## Naming 

C programming language does not have namespaces, thus prefixes often play role of namespaces in C code.

The library uses prefixes in names of types, constants and functions to avoid name conflict with of othr libraries.

### Library prefix (the main prefix)

The main prefix is **BGC** which means **B**asic **G**eometric **C**omputations.

The structure types and the contstans have prefix in the form **BGC_**.

For example, structures:
- BGC_FP64_Vector3
- BGC_FP32_Quaternion
- BGC_FP32_Matrix2x2

Constants:
- BGC_FP32_EPSILON
- BGC_FP64_TWO_PI

The functions have prefix in the form **bgc_**, for example:
- bgc_fp32_turn3_combine
- bgc_fp64_matrix3x3_subtract

### Basic type prefix (the secondary prefix)

Prefixs of type ends the names of constats, types and functions of the library.

The library uses two types of floating point numbers: **float** and  **double** (**binary32** and **binary64** types of the **IEEE 754** standard).

Thus there are two prefixes of types:
- **FP32** - means **F**loating **P**oint, **32** bit, which corresponds to the **float** type of the C programming language.
- **FP64** - means **F**loating **P**oint, **64** bit, which corresponds to the **double** type of the C programming language.

The constants and the types of structures which are based in the **float** type have **FP32_** as the type prefix:
- BGC_FP32_Vector3
- BGC_FP32_Matrix3x2
- BGC_FP32_Quaternion
- BGC_FP32_PI
- BGC_FP32_EPSILON

The constants and the types of structures which are based in the **double** type have **FP64_** as the type prefix:
- BGC_FP64_Vector2
- BGC_FP64_Matrix2x3
- BGC_FP64_Turn3
- BGC_FP64_HALF_PI
- BGC_FP64_ONE_THIRD

The functions which works with data of the **float** type have **fp32_** as the type prefix:
- bcg_fp32_vector2_get_length
- bgc_fp32_radians_to_degrees

The functions which works with data of the **double** type have **fp64_** as the type prefix:
- bgc_fp64_vector3_reset
- bgc_fp64_normalize_radians.

Using of such prefixes of a basic type allows to enhance the library with new basic types in future.

### Data types

- [2D-vectors](vector2-eng.md)
- [3D-vectors](vector3-eng.md)
- [Quaternions](quaternion-rus.md)