cogl_vector3_init ()

void                cogl_vector3_init                   (float *vector,
                                                         float x,
                                                         float y,
                                                         float z);

Initializes a 3 component, single precision float vector which can then be manipulated with the cogl_vector convenience APIs. Vectors can also be used in places where a "point" is often desired.

Since 1.4

Stability Level: Unstable

cogl_vector3_init_zero ()

void                cogl_vector3_init_zero              (float *vector);

Initializes a 3 component, single precision float vector with zero for each component.

Since 1.4

Stability Level: Unstable

cogl_vector3_equal ()

CoglBool            cogl_vector3_equal                  (const void *v1,
                                                         const void *v2);

Compares the components of two vectors and returns TRUE if they are the same.

The comparison of the components is done with the '==' operator such that -0 is considered equal to 0, but otherwise there is no fuzziness such as an epsilon to consider vectors that are essentially identical except for some minor precision error differences due to the way they have been manipulated.

Since 1.4

Stability Level: Unstable

cogl_vector3_equal_with_epsilon ()

CoglBool            cogl_vector3_equal_with_epsilon     (const float *vector0,
                                                         const float *vector1,
                                                         float epsilon);

Compares the components of two vectors using the given epsilon and returns TRUE if they are the same, using an internal epsilon for comparing the floats.

Each component is compared against the epsilon value in this way:

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if (fabsf (vector0->x - vector1->x) < epsilon)

Since 1.4

Stability Level: Unstable

cogl_vector3_copy ()

float *             cogl_vector3_copy                   (const float *vector);

Allocates a new 3 component float vector on the heap initializing the components from the given vector and returns a pointer to the newly allocated vector. You should free the memory using cogl_vector3_free()

Since 1.4

Stability Level: Unstable

cogl_vector3_free ()

void                cogl_vector3_free                   (float *vector);

Frees a 3 component vector that was previously allocated with cogl_vector3_copy()

Since 1.4

Stability Level: Unstable

cogl_vector3_invert ()

void                cogl_vector3_invert                 (float *vector);

Inverts/negates all the components of the given vector.

Since 1.4

Stability Level: Unstable

cogl_vector3_add ()

void                cogl_vector3_add                    (float *result,
                                                         const float *a,
                                                         const float *b);

Adds each of the corresponding components in vectors a and b storing the results in result.

Since 1.4

Stability Level: Unstable

cogl_vector3_subtract ()

void                cogl_vector3_subtract               (float *result,
                                                         const float *a,
                                                         const float *b);

Subtracts each of the corresponding components in vector b from a storing the results in result.

Since 1.4

Stability Level: Unstable

cogl_vector3_multiply_scalar ()

void                cogl_vector3_multiply_scalar        (float *vector,
                                                         float scalar);

Multiplies each of the vector components by the given scalar.

Since 1.4

Stability Level: Unstable

cogl_vector3_divide_scalar ()

void                cogl_vector3_divide_scalar          (float *vector,
                                                         float scalar);

Divides each of the vector components by the given scalar.

Since 1.4

Stability Level: Unstable

cogl_vector3_normalize ()

void                cogl_vector3_normalize              (float *vector);

Updates the vector so it is a "unit vector" such that the vectors magnitude or length is equal to 1.

Since 1.4

Stability Level: Unstable

cogl_vector3_magnitude ()

float               cogl_vector3_magnitude              (const float *vector);

Calculates the scalar magnitude or length of vector.

Since 1.4

Stability Level: Unstable

cogl_vector3_cross_product ()

void                cogl_vector3_cross_product          (float *result,
                                                         const float *u,
                                                         const float *v);

Calculates the cross product between the two vectors u and v.

The cross product is a vector perpendicular to both u and v. This can be useful for calculating the normal of a polygon by creating two vectors in its plane using the polygons vertices and taking their cross product.

If the two vectors are parallel then the cross product is 0.

You can use a right hand rule to determine which direction the perpendicular vector will point: If you place the two vectors tail, to tail and imagine grabbing the perpendicular line that extends through the common tail with your right hand such that you fingers rotate in the direction from u to v then the resulting vector points along your extended thumb.

Since 1.4

Stability Level: Unstable

cogl_vector3_dot_product ()

float               cogl_vector3_dot_product            (const float *a,
                                                         const float *b);

Calculates the dot product of the two 3 component vectors. This can be used to determine the magnitude of one vector projected onto another. (for example a surface normal)

For example if you have a polygon with a given normal vector and some other point for which you want to calculate its distance from the polygon, you can create a vector between one of the polygon vertices and that point and use the dot product to calculate the magnitude for that vector but projected onto the normal of the polygon. This way you don't just get the distance from the point to the edge of the polygon you get the distance from the point to the nearest part of the polygon.

The dot product is calculated as:

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(a->x * b->x + a->y * b->y + a->z * b->z)

For reference, the dot product can also be calculated from the angle between two vectors as:

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|a||b|cos𝜃

Since 1.4

Stability Level: Unstable

cogl_vector3_distance ()

float               cogl_vector3_distance               (const float *a,
                                                         const float *b);

If you consider the two given vectors as (x,y,z) points instead then this will compute the distance between those two points.

Since 1.4

Stability Level: Unstable