GimpVector

GimpVector — Utilities to set up and manipulate vectors.

Synopsis

struct              GimpVector2;
struct              GimpVector3;
struct              GimpVector4;
GimpVector2         gimp_vector2_new                    (gdouble x,
                                                         gdouble y);
void                gimp_vector2_set                    (GimpVector2 *vector,
                                                         gdouble x,
                                                         gdouble y);
gdouble             gimp_vector2_length                 (const GimpVector2 *vector);
gdouble             gimp_vector2_length_val             (GimpVector2 vector);
void                gimp_vector2_mul                    (GimpVector2 *vector,
                                                         gdouble factor);
GimpVector2         gimp_vector2_mul_val                (GimpVector2 vector,
                                                         gdouble factor);
GimpVector2         gimp_vector2_normal                 (GimpVector2 *vector);
GimpVector2         gimp_vector2_normal_val             (GimpVector2 vector);
void                gimp_vector2_normalize              (GimpVector2 *vector);
GimpVector2         gimp_vector2_normalize_val          (GimpVector2 vector);
void                gimp_vector2_neg                    (GimpVector2 *vector);
GimpVector2         gimp_vector2_neg_val                (GimpVector2 vector);
void                gimp_vector2_add                    (GimpVector2 *result,
                                                         const GimpVector2 *vector1,
                                                         const GimpVector2 *vector2);
GimpVector2         gimp_vector2_add_val                (GimpVector2 vector1,
                                                         GimpVector2 vector2);
void                gimp_vector2_sub                    (GimpVector2 *result,
                                                         const GimpVector2 *vector1,
                                                         const GimpVector2 *vector2);
GimpVector2         gimp_vector2_sub_val                (GimpVector2 vector1,
                                                         GimpVector2 vector2);
gdouble             gimp_vector2_inner_product          (const GimpVector2 *vector1,
                                                         const GimpVector2 *vector2);
gdouble             gimp_vector2_inner_product_val      (GimpVector2 vector1,
                                                         GimpVector2 vector2);
GimpVector2         gimp_vector2_cross_product          (const GimpVector2 *vector1,
                                                         const GimpVector2 *vector2);
GimpVector2         gimp_vector2_cross_product_val      (GimpVector2 vector1,
                                                         GimpVector2 vector2);
void                gimp_vector2_rotate                 (GimpVector2 *vector,
                                                         gdouble alpha);
GimpVector2         gimp_vector2_rotate_val             (GimpVector2 vector,
                                                         gdouble alpha);
GimpVector3         gimp_vector3_new                    (gdouble x,
                                                         gdouble y,
                                                         gdouble z);
void                gimp_vector3_set                    (GimpVector3 *vector,
                                                         gdouble x,
                                                         gdouble y,
                                                         gdouble z);
gdouble             gimp_vector3_length                 (const GimpVector3 *vector);
gdouble             gimp_vector3_length_val             (GimpVector3 vector);
void                gimp_vector3_mul                    (GimpVector3 *vector,
                                                         gdouble factor);
GimpVector3         gimp_vector3_mul_val                (GimpVector3 vector,
                                                         gdouble factor);
void                gimp_vector3_normalize              (GimpVector3 *vector);
GimpVector3         gimp_vector3_normalize_val          (GimpVector3 vector);
void                gimp_vector3_neg                    (GimpVector3 *vector);
GimpVector3         gimp_vector3_neg_val                (GimpVector3 vector);
void                gimp_vector3_add                    (GimpVector3 *result,
                                                         const GimpVector3 *vector1,
                                                         const GimpVector3 *vector2);
GimpVector3         gimp_vector3_add_val                (GimpVector3 vector1,
                                                         GimpVector3 vector2);
void                gimp_vector3_sub                    (GimpVector3 *result,
                                                         const GimpVector3 *vector1,
                                                         const GimpVector3 *vector2);
GimpVector3         gimp_vector3_sub_val                (GimpVector3 vector1,
                                                         GimpVector3 vector2);
gdouble             gimp_vector3_inner_product          (const GimpVector3 *vector1,
                                                         const GimpVector3 *vector2);
gdouble             gimp_vector3_inner_product_val      (GimpVector3 vector1,
                                                         GimpVector3 vector2);
GimpVector3         gimp_vector3_cross_product          (const GimpVector3 *vector1,
                                                         const GimpVector3 *vector2);
GimpVector3         gimp_vector3_cross_product_val      (GimpVector3 vector1,
                                                         GimpVector3 vector2);
void                gimp_vector3_rotate                 (GimpVector3 *vector,
                                                         gdouble alpha,
                                                         gdouble beta,
                                                         gdouble gamma);
GimpVector3         gimp_vector3_rotate_val             (GimpVector3 vector,
                                                         gdouble alpha,
                                                         gdouble beta,
                                                         gdouble gamma);
void                gimp_vector_2d_to_3d                (gint sx,
                                                         gint sy,
                                                         gint w,
                                                         gint h,
                                                         gint x,
                                                         gint y,
                                                         const GimpVector3 *vp,
                                                         GimpVector3 *p);
GimpVector3         gimp_vector_2d_to_3d_val            (gint sx,
                                                         gint sy,
                                                         gint w,
                                                         gint h,
                                                         gint x,
                                                         gint y,
                                                         GimpVector3 vp,
                                                         GimpVector3 p);
void                gimp_vector_3d_to_2d                (gint sx,
                                                         gint sy,
                                                         gint w,
                                                         gint h,
                                                         gdouble *x,
                                                         gdouble *y,
                                                         const GimpVector3 *vp,
                                                         const GimpVector3 *p);

Description

Utilities to set up and manipulate vectors.

Details

struct GimpVector2

struct GimpVector2 {
  gdouble x, y;
};

A two dimensional vector.

gdouble x;

the x axis

gdouble y;

the y axis

struct GimpVector3

struct GimpVector3 {
  gdouble x, y, z;
};

A three dimensional vector.

gdouble x;

the x axis

gdouble y;

the y axis

gdouble z;

the z axis

struct GimpVector4

struct GimpVector4 {
  gdouble x, y, z, w;
};

A four dimensional vector.

gdouble x;

the x axis

gdouble y;

the y axis

gdouble z;

the z axis

gdouble w;

the w axis

gimp_vector2_new ()

GimpVector2         gimp_vector2_new                    (gdouble x,
                                                         gdouble y);

Creates a GimpVector2 of coordinates x and y.

x :

the X coordinate.

y :

the Y coordinate.

Returns :

the resulting GimpVector2.

gimp_vector2_set ()

void                gimp_vector2_set                    (GimpVector2 *vector,
                                                         gdouble x,
                                                         gdouble y);

Sets the X and Y coordinates of vector to x and y.

vector :

a pointer to a GimpVector2.

x :

the X coordinate.

y :

the Y coordinate.

gimp_vector2_length ()

gdouble             gimp_vector2_length                 (const GimpVector2 *vector);

Computes the length of a 2D vector.

vector :

a pointer to a GimpVector2.

Returns :

the length of vector (a positive gdouble).

gimp_vector2_length_val ()

gdouble             gimp_vector2_length_val             (GimpVector2 vector);

This function is identical to gimp_vector2_length() but the vector is passed by value rather than by reference.

vector :

a GimpVector2.

Returns :

the length of vector (a positive gdouble).

gimp_vector2_mul ()

void                gimp_vector2_mul                    (GimpVector2 *vector,
                                                         gdouble factor);

Multiplies each component of the vector by factor. Note that this is equivalent to multiplying the vectors length by factor.

vector :

a pointer to a GimpVector2.

factor :

a scalar.

gimp_vector2_mul_val ()

GimpVector2         gimp_vector2_mul_val                (GimpVector2 vector,
                                                         gdouble factor);

This function is identical to gimp_vector2_mul() but the vector is passed by value rather than by reference.

vector :

a GimpVector2.

factor :

a scalar.

Returns :

the resulting GimpVector2.

gimp_vector2_normal ()

GimpVector2         gimp_vector2_normal                 (GimpVector2 *vector);

Compute a normalized perpendicular vector to vector

vector :

a pointer to a GimpVector2.

Returns :

a GimpVector2 perpendicular to vector, with a length of 1.0.

Since 2.8


gimp_vector2_normal_val ()

GimpVector2         gimp_vector2_normal_val             (GimpVector2 vector);

This function is identical to gimp_vector2_normal() but the vector is passed by value rather than by reference.

vector :

a GimpVector2.

Returns :

a GimpVector2 perpendicular to vector, with a length of 1.0.

Since 2.8


gimp_vector2_normalize ()

void                gimp_vector2_normalize              (GimpVector2 *vector);

Normalizes the vector so the length of the vector is 1.0. The nul vector will not be changed.

vector :

a pointer to a GimpVector2.

gimp_vector2_normalize_val ()

GimpVector2         gimp_vector2_normalize_val          (GimpVector2 vector);

This function is identical to gimp_vector2_normalize() but the vector is passed by value rather than by reference.

vector :

a GimpVector2.

Returns :

a GimpVector2 parallel to vector, pointing in the same direction but with a length of 1.0.

gimp_vector2_neg ()

void                gimp_vector2_neg                    (GimpVector2 *vector);

Negates the vector (i.e. negate all its coordinates).

vector :

a pointer to a GimpVector2.

gimp_vector2_neg_val ()

GimpVector2         gimp_vector2_neg_val                (GimpVector2 vector);

This function is identical to gimp_vector2_neg() but the vector is passed by value rather than by reference.

vector :

a GimpVector2.

Returns :

the negated GimpVector2.

gimp_vector2_add ()

void                gimp_vector2_add                    (GimpVector2 *result,
                                                         const GimpVector2 *vector1,
                                                         const GimpVector2 *vector2);

Computes the sum of two 2D vectors. The resulting GimpVector2 is stored in result.

result :

destination for the resulting GimpVector2.

vector1 :

a pointer to the first GimpVector2.

vector2 :

a pointer to the second GimpVector2.

gimp_vector2_add_val ()

GimpVector2         gimp_vector2_add_val                (GimpVector2 vector1,
                                                         GimpVector2 vector2);

This function is identical to gimp_vector2_add() but the vectors are passed by value rather than by reference.

vector1 :

the first GimpVector2.

vector2 :

the second GimpVector2.

Returns :

the resulting GimpVector2.

gimp_vector2_sub ()

void                gimp_vector2_sub                    (GimpVector2 *result,
                                                         const GimpVector2 *vector1,
                                                         const GimpVector2 *vector2);

Computes the difference of two 2D vectors (vector1 minus vector2). The resulting GimpVector2 is stored in result.

result :

the destination for the resulting GimpVector2.

vector1 :

a pointer to the first GimpVector2.

vector2 :

a pointer to the second GimpVector2.

gimp_vector2_sub_val ()

GimpVector2         gimp_vector2_sub_val                (GimpVector2 vector1,
                                                         GimpVector2 vector2);

This function is identical to gimp_vector2_sub() but the vectors are passed by value rather than by reference.

vector1 :

the first GimpVector2.

vector2 :

the second GimpVector2.

Returns :

the resulting GimpVector2.

gimp_vector2_inner_product ()

gdouble             gimp_vector2_inner_product          (const GimpVector2 *vector1,
                                                         const GimpVector2 *vector2);

Computes the inner (dot) product of two 2D vectors. This product is zero if and only if the two vectors are orthognal.

vector1 :

a pointer to the first GimpVector2.

vector2 :

a pointer to the second GimpVector2.

Returns :

The inner product.

gimp_vector2_inner_product_val ()

gdouble             gimp_vector2_inner_product_val      (GimpVector2 vector1,
                                                         GimpVector2 vector2);

This function is identical to gimp_vector2_inner_product() but the vectors are passed by value rather than by reference.

vector1 :

the first GimpVector2.

vector2 :

the second GimpVector2.

Returns :

The inner product.

gimp_vector2_cross_product ()

GimpVector2         gimp_vector2_cross_product          (const GimpVector2 *vector1,
                                                         const GimpVector2 *vector2);

Compute the cross product of two vectors. The result is a GimpVector2 which is orthognal to both vector1 and vector2. If vector1 and vector2 are parallel, the result will be the nul vector.

Note that in 2D, this function is useful to test if two vectors are parallel or not, or to compute the area spawned by two vectors.

vector1 :

a pointer to the first GimpVector2.

vector2 :

a pointer to the second GimpVector2.

Returns :

The cross product.

gimp_vector2_cross_product_val ()

GimpVector2         gimp_vector2_cross_product_val      (GimpVector2 vector1,
                                                         GimpVector2 vector2);

This function is identical to gimp_vector2_cross_product() but the vectors are passed by value rather than by reference.

vector1 :

the first GimpVector2.

vector2 :

the second GimpVector2.

Returns :

The cross product.

gimp_vector2_rotate ()

void                gimp_vector2_rotate                 (GimpVector2 *vector,
                                                         gdouble alpha);

Rotates the vector counterclockwise by alpha radians.

vector :

a pointer to a GimpVector2.

alpha :

an angle (in radians).

gimp_vector2_rotate_val ()

GimpVector2         gimp_vector2_rotate_val             (GimpVector2 vector,
                                                         gdouble alpha);

This function is identical to gimp_vector2_rotate() but the vector is passed by value rather than by reference.

vector :

a GimpVector2.

alpha :

an angle (in radians).

Returns :

a GimpVector2 representing vector rotated by alpha radians.

gimp_vector3_new ()

GimpVector3         gimp_vector3_new                    (gdouble x,
                                                         gdouble y,
                                                         gdouble z);

Creates a GimpVector3 of coordinate x, y and z.

x :

the X coordinate.

y :

the Y coordinate.

z :

the Z coordinate.

Returns :

the resulting GimpVector3.

gimp_vector3_set ()

void                gimp_vector3_set                    (GimpVector3 *vector,
                                                         gdouble x,
                                                         gdouble y,
                                                         gdouble z);

Sets the X, Y and Z coordinates of vector to x, y and z.

vector :

a pointer to a GimpVector3.

x :

the X coordinate.

y :

the Y coordinate.

z :

the Z coordinate.

gimp_vector3_length ()

gdouble             gimp_vector3_length                 (const GimpVector3 *vector);

Computes the length of a 3D vector.

vector :

a pointer to a GimpVector3.

Returns :

the length of vector (a positive gdouble).

gimp_vector3_length_val ()

gdouble             gimp_vector3_length_val             (GimpVector3 vector);

This function is identical to gimp_vector3_length() but the vector is passed by value rather than by reference.

vector :

a GimpVector3.

Returns :

the length of vector (a positive gdouble).

gimp_vector3_mul ()

void                gimp_vector3_mul                    (GimpVector3 *vector,
                                                         gdouble factor);

Multiplies each component of the vector by factor. Note that this is equivalent to multiplying the vectors length by factor.

vector :

a pointer to a GimpVector3.

factor :

a scalar.

gimp_vector3_mul_val ()

GimpVector3         gimp_vector3_mul_val                (GimpVector3 vector,
                                                         gdouble factor);

This function is identical to gimp_vector3_mul() but the vector is passed by value rather than by reference.

vector :

a GimpVector3.

factor :

a scalar.

Returns :

the resulting GimpVector3.

gimp_vector3_normalize ()

void                gimp_vector3_normalize              (GimpVector3 *vector);

Normalizes the vector so the length of the vector is 1.0. The nul vector will not be changed.

vector :

a pointer to a GimpVector3.

gimp_vector3_normalize_val ()

GimpVector3         gimp_vector3_normalize_val          (GimpVector3 vector);

This function is identical to gimp_vector3_normalize() but the vector is passed by value rather than by reference.

vector :

a GimpVector3.

Returns :

a GimpVector3 parallel to vector, pointing in the same direction but with a length of 1.0.

gimp_vector3_neg ()

void                gimp_vector3_neg                    (GimpVector3 *vector);

Negates the vector (i.e. negate all its coordinates).

vector :

a pointer to a GimpVector3.

gimp_vector3_neg_val ()

GimpVector3         gimp_vector3_neg_val                (GimpVector3 vector);

This function is identical to gimp_vector3_neg() but the vector is passed by value rather than by reference.

vector :

a GimpVector3.

Returns :

the negated GimpVector3.

gimp_vector3_add ()

void                gimp_vector3_add                    (GimpVector3 *result,
                                                         const GimpVector3 *vector1,
                                                         const GimpVector3 *vector2);

Computes the sum of two 3D vectors. The resulting GimpVector3 is stored in result.

result :

destination for the resulting GimpVector3.

vector1 :

a pointer to the first GimpVector3.

vector2 :

a pointer to the second GimpVector3.

gimp_vector3_add_val ()

GimpVector3         gimp_vector3_add_val                (GimpVector3 vector1,
                                                         GimpVector3 vector2);

This function is identical to gimp_vector3_add() but the vectors are passed by value rather than by reference.

vector1 :

a GimpVector3.

vector2 :

a GimpVector3.

Returns :

the resulting GimpVector3.

gimp_vector3_sub ()

void                gimp_vector3_sub                    (GimpVector3 *result,
                                                         const GimpVector3 *vector1,
                                                         const GimpVector3 *vector2);

Computes the difference of two 3D vectors (vector1 minus vector2). The resulting GimpVector3 is stored in result.

result :

the destination for the resulting GimpVector3.

vector1 :

a pointer to the first GimpVector3.

vector2 :

a pointer to the second GimpVector3.

gimp_vector3_sub_val ()

GimpVector3         gimp_vector3_sub_val                (GimpVector3 vector1,
                                                         GimpVector3 vector2);

This function is identical to gimp_vector3_sub() but the vectors are passed by value rather than by reference.

vector1 :

a GimpVector3.

vector2 :

a GimpVector3.

Returns :

the resulting GimpVector3.

gimp_vector3_inner_product ()

gdouble             gimp_vector3_inner_product          (const GimpVector3 *vector1,
                                                         const GimpVector3 *vector2);

Computes the inner (dot) product of two 3D vectors. This product is zero if and only if the two vectors are orthognal.

vector1 :

a pointer to the first GimpVector3.

vector2 :

a pointer to the second GimpVector3.

Returns :

The inner product.

gimp_vector3_inner_product_val ()

gdouble             gimp_vector3_inner_product_val      (GimpVector3 vector1,
                                                         GimpVector3 vector2);

This function is identical to gimp_vector3_inner_product() but the vectors are passed by value rather than by reference.

vector1 :

the first GimpVector3.

vector2 :

the second GimpVector3.

Returns :

The inner product.

gimp_vector3_cross_product ()

GimpVector3         gimp_vector3_cross_product          (const GimpVector3 *vector1,
                                                         const GimpVector3 *vector2);

Compute the cross product of two vectors. The result is a GimpVector3 which is orthognal to both vector1 and vector2. If vector1 and vector2 and parallel, the result will be the nul vector.

This function can be used to compute the normal of the plane defined by vector1 and vector2.

vector1 :

a pointer to the first GimpVector3.

vector2 :

a pointer to the second GimpVector3.

Returns :

The cross product.

gimp_vector3_cross_product_val ()

GimpVector3         gimp_vector3_cross_product_val      (GimpVector3 vector1,
                                                         GimpVector3 vector2);

This function is identical to gimp_vector3_cross_product() but the vectors are passed by value rather than by reference.

vector1 :

the first GimpVector3.

vector2 :

the second GimpVector3.

Returns :

The cross product.

gimp_vector3_rotate ()

void                gimp_vector3_rotate                 (GimpVector3 *vector,
                                                         gdouble alpha,
                                                         gdouble beta,
                                                         gdouble gamma);

Rotates the vector around the three axis (Z, Y, and X) by alpha, beta and gamma, respectively.

Note that the order of the rotation is very important. If you expect a vector to be rotated around X, and then around Y, you will have to call this function twice. Also, it is often wise to call this function with only one of alpha, beta and gamma non-zero.

vector :

a pointer to a GimpVector3.

alpha :

the angle (in radian) of rotation around the Z axis.

beta :

the angle (in radian) of rotation around the Y axis.

gamma :

the angle (in radian) of rotation around the X axis.

gimp_vector3_rotate_val ()

GimpVector3         gimp_vector3_rotate_val             (GimpVector3 vector,
                                                         gdouble alpha,
                                                         gdouble beta,
                                                         gdouble gamma);

This function is identical to gimp_vector3_rotate() but the vectors are passed by value rather than by reference.

vector :

a GimpVector3.

alpha :

the angle (in radian) of rotation around the Z axis.

beta :

the angle (in radian) of rotation around the Y axis.

gamma :

the angle (in radian) of rotation around the X axis.

Returns :

the rotated vector.

gimp_vector_2d_to_3d ()

void                gimp_vector_2d_to_3d                (gint sx,
                                                         gint sy,
                                                         gint w,
                                                         gint h,
                                                         gint x,
                                                         gint y,
                                                         const GimpVector3 *vp,
                                                         GimpVector3 *p);

\"Compute screen (sx, sy) - (sx + w, sy + h) to 3D unit square mapping. The plane to map to is given in the z field of p. The observer is located at position vp (vp->z != 0.0).\"

In other words, this computes the projection of the point (x, y) to the plane z = p->z (parallel to XY), from the vp point of view through the screen (sx, sy)->(sx + w, sy + h)

sx :

the abscisse of the upper-left screen rectangle.

sy :

the ordinate of the upper-left screen rectangle.

w :

the width of the screen rectangle.

h :

the height of the screen rectangle.

x :

the abscisse of the point in the screen rectangle to map.

y :

the ordinate of the point in the screen rectangle to map.

vp :

the position of the observer.

p :

the resulting point.

gimp_vector_2d_to_3d_val ()

GimpVector3         gimp_vector_2d_to_3d_val            (gint sx,
                                                         gint sy,
                                                         gint w,
                                                         gint h,
                                                         gint x,
                                                         gint y,
                                                         GimpVector3 vp,
                                                         GimpVector3 p);

This function is identical to gimp_vector_2d_to_3d() but the position of the observer and the resulting point p are passed by value rather than by reference.

sx :

the abscisse of the upper-left screen rectangle.

sy :

the ordinate of the upper-left screen rectangle.

w :

the width of the screen rectangle.

h :

the height of the screen rectangle.

x :

the abscisse of the point in the screen rectangle to map.

y :

the ordinate of the point in the screen rectangle to map.

vp :

position of the observer.

p :

the resulting point.

Returns :

the computed GimpVector3 point.

gimp_vector_3d_to_2d ()

void                gimp_vector_3d_to_2d                (gint sx,
                                                         gint sy,
                                                         gint w,
                                                         gint h,
                                                         gdouble *x,
                                                         gdouble *y,
                                                         const GimpVector3 *vp,
                                                         const GimpVector3 *p);

Convert the given 3D point to 2D (project it onto the viewing plane, (sx, sy, 0) - (sx + w, sy + h, 0). The input is assumed to be in the unit square (0, 0, z) - (1, 1, z). The viewpoint of the observer is passed in vp.

This is basically the opposite of gimp_vector_2d_to_3d().

sx :

the abscisse of the upper-left screen rectangle.

sy :

the ordinate of the upper-left screen rectangle.

w :

the width of the screen rectangle.

h :

the height of the screen rectangle.

x :

the abscisse of the point in the screen rectangle to map (return value).

y :

the ordinate of the point in the screen rectangle to map (return value).

vp :

position of the observer.

p :

the 3D point to project to the plane.

See Also

GimpMatrix2, GimpMatrix3, GimpMatrix4