Triangle: Graphene Reference Manual

## Triangle Triangle — A triangle described by 3D points |

## Functions

graphene_triangle_t * | graphene_triangle_alloc ()
void | graphene_triangle_free ()
graphene_triangle_t * | graphene_triangle_init_from_point3d ()
graphene_triangle_t * | graphene_triangle_init_from_vec3 ()
void | graphene_triangle_get_points ()
void | graphene_triangle_get_vertices ()
float | graphene_triangle_get_area ()
void | graphene_triangle_get_midpoint ()
void | graphene_triangle_get_normal ()
void | graphene_triangle_get_plane ()
void | graphene_triangle_get_bounding_box ()
bool | graphene_triangle_get_barycoords ()
bool | graphene_triangle_contains_point ()
bool | graphene_triangle_equal ()

## Types and Values

| graphene_triangle_t

## Includes

    #include <graphene.h>

## Description

graphene_triangle_t represents a triangle in 3D space.

## Functions

### graphene_triangle_alloc ()

    graphene_triangle_t *
    graphene_triangle_alloc (void);

Allocates a new graphene_triangle_t.

The contents of the returned structure are undefined.

[constructor]

#### Returns

the newly allocated graphene_triangle_t structure. Use `graphene_triangle_free()` to free the resources allocated by this function.

[transfer full]

Since: 1.2

### graphene_triangle_free ()

    void
    graphene_triangle_free (graphene_triangle_t *t);

Frees the resources allocated by `graphene_triangle_alloc()`.

#### Parameters

t | a graphene_triangle_t |

Since: 1.2

### graphene_triangle_init_from_point3d ()

    graphene_triangle_t *
    graphene_triangle_init_from_point3d (graphene_triangle_t *t,
                                         const graphene_point3d_t *a,
                                         const graphene_point3d_t *b,
                                         const graphene_point3d_t *c);

Initializes a graphene_triangle_t using the three given 3D points.

#### Parameters

t | the graphene_triangle_t to initialize |
a | a graphene_point3d_t. | [nullable]
b | a graphene_point3d_t. | [nullable]
c | a graphene_point3d_t. | [nullable]

#### Returns

the initialized graphene_triangle_t.

[transfer none]

Since: 1.2

### graphene_triangle_init_from_vec3 ()

    graphene_triangle_t *
    graphene_triangle_init_from_vec3 (graphene_triangle_t *t,
                                      const graphene_vec3_t *a,
                                      const graphene_vec3_t *b,
                                      const graphene_vec3_t *c);

Initializes a graphene_triangle_t using the three given vectors.

#### Parameters

t | the graphene_triangle_t to initialize |
a | a graphene_vec3_t. | [nullable]
b | a graphene_vec3_t. | [nullable]
c | a graphene_vec3_t. | [nullable]

#### Returns

the initialized graphene_triangle_t.

[transfer none]

Since: 1.2

### graphene_triangle_get_points ()

    void
    graphene_triangle_get_points (const graphene_triangle_t *t,
                                  graphene_point3d_t *a,
                                  graphene_point3d_t *b,
                                  graphene_point3d_t *c);

Retrieves the three vertices of the given graphene_triangle_t and returns their coordinates as graphene_point3d_t.

#### Parameters

t | a graphene_triangle_t |
a | return location for the coordinates of the first vertex. | [out caller-allocates][optional]
b | return location for the coordinates of the second vertex. | [out caller-allocates][optional]
c | return location for the coordinates of the third vertex. | [out caller-allocates][optional]

Since: 1.2

### graphene_triangle_get_vertices ()

    void
    graphene_triangle_get_vertices (const graphene_triangle_t *t,
                                    graphene_vec3_t *a,
                                    graphene_vec3_t *b,
                                    graphene_vec3_t *c);

Retrieves the three vertices of the given graphene_triangle_t.

#### Parameters

t | a graphene_triangle_t |
a | return location for the first vertex. | [out caller-allocates][optional]
b | return location for the second vertex. | [out caller-allocates][optional]
c | return location for the third vertex. | [out caller-allocates][optional]

Since: 1.2

### graphene_triangle_get_area ()

    float
    graphene_triangle_get_area (const graphene_triangle_t *t);

Computes the area of the given graphene_triangle_t.

#### Parameters

t | a graphene_triangle_t |

#### Returns

the area of the triangle

Since: 1.2

### graphene_triangle_get_midpoint ()

    void
    graphene_triangle_get_midpoint (const graphene_triangle_t *t,
                                    graphene_point3d_t *res);

Computes the coordinates of the midpoint of the given graphene_triangle_t.

The midpoint G is the centroid of the triangle, i.e. the intersection of its medians.

#### Parameters

t | a graphene_triangle_t |
res | return location for the coordinates of the midpoint. | [out caller-allocates]

Since: 1.2

### graphene_triangle_get_normal ()

    void
    graphene_triangle_get_normal (const graphene_triangle_t *t,
                                  graphene_vec3_t *res);

Computes the normal vector of the given graphene_triangle_t.

#### Parameters

t | a graphene_triangle_t |
res | return location for the normal vector. | [out caller-allocates]

Since: 1.2

### graphene_triangle_get_plane ()

    void
    graphene_triangle_get_plane (const graphene_triangle_t *t,
                                 graphene_plane_t *res);

Computes the plane based on the vertices of the given graphene_triangle_t.

#### Parameters

t | a graphene_triangle_t |
res | return location for the plane. | [out caller-allocates]

Since: 1.2

### graphene_triangle_get_bounding_box ()

    void
    graphene_triangle_get_bounding_box (const graphene_triangle_t *t,
                                        graphene_box_t *res);

Computes the bounding box of the given graphene_triangle_t.

#### Parameters

t | a graphene_triangle_t |
res | return location for the box. | [out caller-allocates]

Since: 1.2

### graphene_triangle_get_barycoords ()

    bool
    graphene_triangle_get_barycoords (const graphene_triangle_t *t,
                                      const graphene_point3d_t *p,
                                      graphene_vec2_t *res);

Computes the barycentric coordinates of the given point `p` .

The point `p` must lie on the same plane as the triangle `t` ; if the point is not coplanar, the result of this function is undefined.

If we place the origin in the coordinates of the triangle's A point, the barycentric coordinates are `u`, which is on the AC vector; and `v` which is on the AB vector:

The returned graphene_vec2_t contains the following values, in order:

- `res.x = u`

- `res.y = v`

#### Parameters

t | a graphene_triangle_t |
p | a graphene_point3d_t. | [nullable]
res | return location for the vector with the barycentric coordinates. | [out caller-allocates]

#### Returns

`true` if the barycentric coordinates are valid

Since: 1.2

### graphene_triangle_contains_point ()

    bool
    graphene_triangle_contains_point (const graphene_triangle_t *t,
                                      const graphene_point3d_t *p);

Checks whether the given triangle `t` contains the point `p` .

#### Parameters

t | a graphene_triangle_t |
p | a graphene_point3d_t |

#### Returns

`true` if the point is inside the triangle

Since: 1.2

### graphene_triangle_equal ()

    bool
    graphene_triangle_equal (const graphene_triangle_t *a,
                             const graphene_triangle_t *b);

Checks whether the two given graphene_triangle_t are equal.

#### Parameters

a | a graphene_triangle_t |
b | a graphene_triangle_t |

#### Returns

`true` if the triangles are equal

Since: 1.2

## Types and Values

### graphene_triangle_t

    typedef struct {
    } graphene_triangle_t;

A triangle.

Since: 1.2