diff options
Diffstat (limited to 'libgimpmath/gimpvector.c')
| -rw-r--r-- | libgimpmath/gimpvector.c | 1129 |
1 files changed, 1129 insertions, 0 deletions
diff --git a/libgimpmath/gimpvector.c b/libgimpmath/gimpvector.c new file mode 100644 index 0000000..5f2b174 --- /dev/null +++ b/libgimpmath/gimpvector.c @@ -0,0 +1,1129 @@ +/* LIBGIMP - The GIMP Library + * Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball + * + * gimpvector.c + * + * The gimp_vector* functions were taken from: + * GCK - The General Convenience Kit + * Copyright (C) 1996 Tom Bech + * + * This library is free software: you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 3 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library. If not, see + * <https://www.gnu.org/licenses/>. + */ + +/**********************************************/ +/* A little collection of useful vector stuff */ +/**********************************************/ + +#include "config.h" + +#include <glib-object.h> + +#include "gimpmath.h" + + +/** + * SECTION: gimpvector + * @title: GimpVector + * @short_description: Utilities to set up and manipulate vectors. + * @see_also: #GimpMatrix2, #GimpMatrix3, #GimpMatrix4 + * + * Utilities to set up and manipulate vectors. + **/ + + +/*************************/ +/* Some useful constants */ +/*************************/ + +static const GimpVector2 gimp_vector2_zero = { 0.0, 0.0 }; +#if 0 +static const GimpVector2 gimp_vector2_unit_x = { 1.0, 0.0 }; +static const GimpVector2 gimp_vector2_unit_y = { 0.0, 1.0 }; +#endif + +static const GimpVector3 gimp_vector3_zero = { 0.0, 0.0, 0.0 }; +#if 0 +static const GimpVector3 gimp_vector3_unit_x = { 1.0, 0.0, 0.0 }; +static const GimpVector3 gimp_vector3_unit_y = { 0.0, 1.0, 0.0 }; +static const GimpVector3 gimp_vector3_unit_z = { 0.0, 0.0, 1.0 }; +#endif + +/**************************************/ +/* Two dimensional vector functions */ +/**************************************/ + +/** + * gimp_vector2_new: + * @x: the X coordinate. + * @y: the Y coordinate. + * + * Creates a #GimpVector2 of coordinates @x and @y. + * + * Returns: the resulting #GimpVector2. + **/ +GimpVector2 +gimp_vector2_new (gdouble x, + gdouble y) +{ + GimpVector2 vector; + + vector.x = x; + vector.y = y; + + return vector; +} + +/** + * gimp_vector2_set: + * @vector: a pointer to a #GimpVector2. + * @x: the X coordinate. + * @y: the Y coordinate. + * + * Sets the X and Y coordinates of @vector to @x and @y. + **/ +void +gimp_vector2_set (GimpVector2 *vector, + gdouble x, + gdouble y) +{ + vector->x = x; + vector->y = y; +} + +/** + * gimp_vector2_length: + * @vector: a pointer to a #GimpVector2. + * + * Computes the length of a 2D vector. + * + * Returns: the length of @vector (a positive gdouble). + **/ +gdouble +gimp_vector2_length (const GimpVector2 *vector) +{ + return (sqrt (vector->x * vector->x + vector->y * vector->y)); +} + +/** + * gimp_vector2_length_val: + * @vector: a #GimpVector2. + * + * This function is identical to gimp_vector2_length() but the + * vector is passed by value rather than by reference. + * + * Returns: the length of @vector (a positive gdouble). + **/ +gdouble +gimp_vector2_length_val (GimpVector2 vector) +{ + return (sqrt (vector.x * vector.x + vector.y * vector.y)); +} + +/** + * gimp_vector2_mul: + * @vector: a pointer to a #GimpVector2. + * @factor: a scalar. + * + * Multiplies each component of the @vector by @factor. Note that this + * is equivalent to multiplying the vectors length by @factor. + **/ +void +gimp_vector2_mul (GimpVector2 *vector, + gdouble factor) +{ + vector->x *= factor; + vector->y *= factor; +} + +/** + * gimp_vector2_mul_val: + * @vector: a #GimpVector2. + * @factor: a scalar. + * + * This function is identical to gimp_vector2_mul() but the vector is + * passed by value rather than by reference. + * + * Returns: the resulting #GimpVector2. + **/ +GimpVector2 +gimp_vector2_mul_val (GimpVector2 vector, + gdouble factor) +{ + GimpVector2 result; + + result.x = vector.x * factor; + result.y = vector.y * factor; + + return result; +} + + +/** + * gimp_vector2_normalize: + * @vector: a pointer to a #GimpVector2. + * + * Normalizes the @vector so the length of the @vector is 1.0. The nul + * vector will not be changed. + **/ +void +gimp_vector2_normalize (GimpVector2 *vector) +{ + gdouble len; + + len = gimp_vector2_length (vector); + + if (len != 0.0) + { + len = 1.0 / len; + vector->x *= len; + vector->y *= len; + } + else + { + *vector = gimp_vector2_zero; + } +} + +/** + * gimp_vector2_normalize_val: + * @vector: a #GimpVector2. + * + * This function is identical to gimp_vector2_normalize() but the + * vector is passed by value rather than by reference. + * + * Returns: a #GimpVector2 parallel to @vector, pointing in the same + * direction but with a length of 1.0. + **/ +GimpVector2 +gimp_vector2_normalize_val (GimpVector2 vector) +{ + GimpVector2 normalized; + gdouble len; + + len = gimp_vector2_length_val (vector); + + if (len != 0.0) + { + len = 1.0 / len; + normalized.x = vector.x * len; + normalized.y = vector.y * len; + return normalized; + } + else + { + return gimp_vector2_zero; + } +} + +/** + * gimp_vector2_neg: + * @vector: a pointer to a #GimpVector2. + * + * Negates the @vector (i.e. negate all its coordinates). + **/ +void +gimp_vector2_neg (GimpVector2 *vector) +{ + vector->x *= -1.0; + vector->y *= -1.0; +} + +/** + * gimp_vector2_neg_val: + * @vector: a #GimpVector2. + * + * This function is identical to gimp_vector2_neg() but the vector + * is passed by value rather than by reference. + * + * Returns: the negated #GimpVector2. + **/ +GimpVector2 +gimp_vector2_neg_val (GimpVector2 vector) +{ + GimpVector2 result; + + result.x = vector.x * -1.0; + result.y = vector.y * -1.0; + + return result; +} + +/** + * gimp_vector2_add: + * @result: destination for the resulting #GimpVector2. + * @vector1: a pointer to the first #GimpVector2. + * @vector2: a pointer to the second #GimpVector2. + * + * Computes the sum of two 2D vectors. The resulting #GimpVector2 is + * stored in @result. + **/ +void +gimp_vector2_add (GimpVector2 *result, + const GimpVector2 *vector1, + const GimpVector2 *vector2) +{ + result->x = vector1->x + vector2->x; + result->y = vector1->y + vector2->y; +} + +/** + * gimp_vector2_add_val: + * @vector1: the first #GimpVector2. + * @vector2: the second #GimpVector2. + * + * This function is identical to gimp_vector2_add() but the vectors + * are passed by value rather than by reference. + * + * Returns: the resulting #GimpVector2. + **/ +GimpVector2 +gimp_vector2_add_val (GimpVector2 vector1, + GimpVector2 vector2) +{ + GimpVector2 result; + + result.x = vector1.x + vector2.x; + result.y = vector1.y + vector2.y; + + return result; +} + +/** + * gimp_vector2_sub: + * @result: the destination for the resulting #GimpVector2. + * @vector1: a pointer to the first #GimpVector2. + * @vector2: a pointer to the second #GimpVector2. + * + * Computes the difference of two 2D vectors (@vector1 minus @vector2). + * The resulting #GimpVector2 is stored in @result. + **/ +void +gimp_vector2_sub (GimpVector2 *result, + const GimpVector2 *vector1, + const GimpVector2 *vector2) +{ + result->x = vector1->x - vector2->x; + result->y = vector1->y - vector2->y; +} + +/** + * gimp_vector2_sub_val: + * @vector1: the first #GimpVector2. + * @vector2: the second #GimpVector2. + * + * This function is identical to gimp_vector2_sub() but the vectors + * are passed by value rather than by reference. + * + * Returns: the resulting #GimpVector2. + **/ +GimpVector2 +gimp_vector2_sub_val (GimpVector2 vector1, + GimpVector2 vector2) +{ + GimpVector2 result; + + result.x = vector1.x - vector2.x; + result.y = vector1.y - vector2.y; + + return result; +} + +/** + * gimp_vector2_inner_product: + * @vector1: a pointer to the first #GimpVector2. + * @vector2: a pointer to the second #GimpVector2. + * + * Computes the inner (dot) product of two 2D vectors. + * This product is zero if and only if the two vectors are orthogonal. + * + * Returns: The inner product. + **/ +gdouble +gimp_vector2_inner_product (const GimpVector2 *vector1, + const GimpVector2 *vector2) +{ + return (vector1->x * vector2->x + vector1->y * vector2->y); +} + +/** + * gimp_vector2_inner_product_val: + * @vector1: the first #GimpVector2. + * @vector2: the second #GimpVector2. + * + * This function is identical to gimp_vector2_inner_product() but the + * vectors are passed by value rather than by reference. + * + * Returns: The inner product. + **/ +gdouble +gimp_vector2_inner_product_val (GimpVector2 vector1, + GimpVector2 vector2) +{ + return (vector1.x * vector2.x + vector1.y * vector2.y); +} + +/** + * gimp_vector2_cross_product: + * @vector1: a pointer to the first #GimpVector2. + * @vector2: a pointer to the second #GimpVector2. + * + * Compute the cross product of two vectors. The result is a + * #GimpVector2 which is orthogonal 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. + * + * Returns: The cross product. + **/ +GimpVector2 +gimp_vector2_cross_product (const GimpVector2 *vector1, + const GimpVector2 *vector2) +{ + GimpVector2 normal; + + normal.x = vector1->x * vector2->y - vector1->y * vector2->x; + normal.y = vector1->y * vector2->x - vector1->x * vector2->y; + + return normal; +} + +/** + * gimp_vector2_cross_product_val: + * @vector1: the first #GimpVector2. + * @vector2: the second #GimpVector2. + * + * This function is identical to gimp_vector2_cross_product() but the + * vectors are passed by value rather than by reference. + * + * Returns: The cross product. + **/ +GimpVector2 +gimp_vector2_cross_product_val (GimpVector2 vector1, + GimpVector2 vector2) +{ + GimpVector2 normal; + + normal.x = vector1.x * vector2.y - vector1.y * vector2.x; + normal.y = vector1.y * vector2.x - vector1.x * vector2.y; + + return normal; +} + +/** + * gimp_vector2_rotate: + * @vector: a pointer to a #GimpVector2. + * @alpha: an angle (in radians). + * + * Rotates the @vector counterclockwise by @alpha radians. + **/ +void +gimp_vector2_rotate (GimpVector2 *vector, + gdouble alpha) +{ + GimpVector2 result; + + result.x = cos (alpha) * vector->x + sin (alpha) * vector->y; + result.y = cos (alpha) * vector->y - sin (alpha) * vector->x; + + *vector = result; +} + +/** + * gimp_vector2_rotate_val: + * @vector: a #GimpVector2. + * @alpha: an angle (in radians). + * + * This function is identical to gimp_vector2_rotate() but the vector + * is passed by value rather than by reference. + * + * Returns: a #GimpVector2 representing @vector rotated by @alpha + * radians. + **/ +GimpVector2 +gimp_vector2_rotate_val (GimpVector2 vector, + gdouble alpha) +{ + GimpVector2 result; + + result.x = cos (alpha) * vector.x + sin (alpha) * vector.y; + result.y = cos (alpha) * vector.y - sin (alpha) * vector.x; + + return result; +} + +/** + * gimp_vector2_normal: + * @vector: a pointer to a #GimpVector2. + * + * Compute a normalized perpendicular vector to @vector + * + * Returns: a #GimpVector2 perpendicular to @vector, with a length of 1.0. + * + * Since: 2.8 + **/ +GimpVector2 +gimp_vector2_normal (GimpVector2 *vector) +{ + GimpVector2 result; + + result.x = - vector->y; + result.y = vector->x; + + gimp_vector2_normalize (&result); + + return result; +} + +/** + * gimp_vector2_normal_val: + * @vector: a #GimpVector2. + * + * This function is identical to gimp_vector2_normal() but the vector + * is passed by value rather than by reference. + * + * Returns: a #GimpVector2 perpendicular to @vector, with a length of 1.0. + * + * Since: 2.8 + **/ +GimpVector2 +gimp_vector2_normal_val (GimpVector2 vector) +{ + GimpVector2 result; + + result.x = - vector.y; + result.y = vector.x; + + gimp_vector2_normalize (&result); + + return result; +} +/**************************************/ +/* Three dimensional vector functions */ +/**************************************/ + +/** + * gimp_vector3_new: + * @x: the X coordinate. + * @y: the Y coordinate. + * @z: the Z coordinate. + * + * Creates a #GimpVector3 of coordinate @x, @y and @z. + * + * Returns: the resulting #GimpVector3. + **/ +GimpVector3 +gimp_vector3_new (gdouble x, + gdouble y, + gdouble z) +{ + GimpVector3 vector; + + vector.x = x; + vector.y = y; + vector.z = z; + + return vector; +} + +/** + * gimp_vector3_set: + * @vector: a pointer to a #GimpVector3. + * @x: the X coordinate. + * @y: the Y coordinate. + * @z: the Z coordinate. + * + * Sets the X, Y and Z coordinates of @vector to @x, @y and @z. + **/ +void +gimp_vector3_set (GimpVector3 *vector, + gdouble x, + gdouble y, + gdouble z) +{ + vector->x = x; + vector->y = y; + vector->z = z; +} + +/** + * gimp_vector3_length: + * @vector: a pointer to a #GimpVector3. + * + * Computes the length of a 3D vector. + * + * Returns: the length of @vector (a positive gdouble). + **/ +gdouble +gimp_vector3_length (const GimpVector3 *vector) +{ + return (sqrt (vector->x * vector->x + + vector->y * vector->y + + vector->z * vector->z)); +} + +/** + * gimp_vector3_length_val: + * @vector: a #GimpVector3. + * + * This function is identical to gimp_vector3_length() but the vector + * is passed by value rather than by reference. + * + * Returns: the length of @vector (a positive gdouble). + **/ +gdouble +gimp_vector3_length_val (GimpVector3 vector) +{ + return (sqrt (vector.x * vector.x + + vector.y * vector.y + + vector.z * vector.z)); +} + +/** + * gimp_vector3_mul: + * @vector: a pointer to a #GimpVector3. + * @factor: a scalar. + * + * Multiplies each component of the @vector by @factor. Note that + * this is equivalent to multiplying the vectors length by @factor. + **/ +void +gimp_vector3_mul (GimpVector3 *vector, + gdouble factor) +{ + vector->x *= factor; + vector->y *= factor; + vector->z *= factor; +} + +/** + * gimp_vector3_mul_val: + * @vector: a #GimpVector3. + * @factor: a scalar. + * + * This function is identical to gimp_vector3_mul() but the vector is + * passed by value rather than by reference. + * + * Returns: the resulting #GimpVector3. + **/ +GimpVector3 +gimp_vector3_mul_val (GimpVector3 vector, + gdouble factor) +{ + GimpVector3 result; + + result.x = vector.x * factor; + result.y = vector.y * factor; + result.z = vector.z * factor; + + return result; +} + +/** + * gimp_vector3_normalize: + * @vector: a pointer to a #GimpVector3. + * + * Normalizes the @vector so the length of the @vector is 1.0. The nul + * vector will not be changed. + **/ +void +gimp_vector3_normalize (GimpVector3 *vector) +{ + gdouble len; + + len = gimp_vector3_length (vector); + + if (len != 0.0) + { + len = 1.0 / len; + vector->x *= len; + vector->y *= len; + vector->z *= len; + } + else + { + *vector = gimp_vector3_zero; + } +} + +/** + * gimp_vector3_normalize_val: + * @vector: a #GimpVector3. + * + * This function is identical to gimp_vector3_normalize() but the + * vector is passed by value rather than by reference. + * + * Returns: a #GimpVector3 parallel to @vector, pointing in the same + * direction but with a length of 1.0. + **/ +GimpVector3 +gimp_vector3_normalize_val (GimpVector3 vector) +{ + GimpVector3 result; + gdouble len; + + len = gimp_vector3_length_val (vector); + + if (len != 0.0) + { + len = 1.0 / len; + result.x = vector.x * len; + result.y = vector.y * len; + result.z = vector.z * len; + return result; + } + else + { + return gimp_vector3_zero; + } +} + +/** + * gimp_vector3_neg: + * @vector: a pointer to a #GimpVector3. + * + * Negates the @vector (i.e. negate all its coordinates). + **/ +void +gimp_vector3_neg (GimpVector3 *vector) +{ + vector->x *= -1.0; + vector->y *= -1.0; + vector->z *= -1.0; +} + +/** + * gimp_vector3_neg_val: + * @vector: a #GimpVector3. + * + * This function is identical to gimp_vector3_neg() but the vector + * is passed by value rather than by reference. + * + * Returns: the negated #GimpVector3. + **/ +GimpVector3 +gimp_vector3_neg_val (GimpVector3 vector) +{ + GimpVector3 result; + + result.x = vector.x * -1.0; + result.y = vector.y * -1.0; + result.z = vector.z * -1.0; + + return result; +} + +/** + * gimp_vector3_add: + * @result: destination for the resulting #GimpVector3. + * @vector1: a pointer to the first #GimpVector3. + * @vector2: a pointer to the second #GimpVector3. + * + * Computes the sum of two 3D vectors. The resulting #GimpVector3 is + * stored in @result. + **/ +void +gimp_vector3_add (GimpVector3 *result, + const GimpVector3 *vector1, + const GimpVector3 *vector2) +{ + result->x = vector1->x + vector2->x; + result->y = vector1->y + vector2->y; + result->z = vector1->z + vector2->z; +} + +/** + * gimp_vector3_add_val: + * @vector1: a #GimpVector3. + * @vector2: a #GimpVector3. + * + * This function is identical to gimp_vector3_add() but the vectors + * are passed by value rather than by reference. + * + * Returns: the resulting #GimpVector3. + **/ +GimpVector3 +gimp_vector3_add_val (GimpVector3 vector1, + GimpVector3 vector2) +{ + GimpVector3 result; + + result.x = vector1.x + vector2.x; + result.y = vector1.y + vector2.y; + result.z = vector1.z + vector2.z; + + return result; +} + +/** + * gimp_vector3_sub: + * @result: the destination for the resulting #GimpVector3. + * @vector1: a pointer to the first #GimpVector3. + * @vector2: a pointer to the second #GimpVector3. + * + * Computes the difference of two 3D vectors (@vector1 minus @vector2). + * The resulting #GimpVector3 is stored in @result. + **/ +void +gimp_vector3_sub (GimpVector3 *result, + const GimpVector3 *vector1, + const GimpVector3 *vector2) +{ + result->x = vector1->x - vector2->x; + result->y = vector1->y - vector2->y; + result->z = vector1->z - vector2->z; +} + +/** + * gimp_vector3_sub_val: + * @vector1: a #GimpVector3. + * @vector2: a #GimpVector3. + * + * This function is identical to gimp_vector3_sub() but the vectors + * are passed by value rather than by reference. + * + * Returns: the resulting #GimpVector3. + **/ +GimpVector3 +gimp_vector3_sub_val (GimpVector3 vector1, + GimpVector3 vector2) +{ + GimpVector3 result; + + result.x = vector1.x - vector2.x; + result.y = vector1.y - vector2.y; + result.z = vector1.z - vector2.z; + + return result; +} + +/** + * gimp_vector3_inner_product: + * @vector1: a pointer to the first #GimpVector3. + * @vector2: a pointer to the second #GimpVector3. + * + * Computes the inner (dot) product of two 3D vectors. This product + * is zero if and only if the two vectors are orthogonal. + * + * Returns: The inner product. + **/ +gdouble +gimp_vector3_inner_product (const GimpVector3 *vector1, + const GimpVector3 *vector2) +{ + return (vector1->x * vector2->x + + vector1->y * vector2->y + + vector1->z * vector2->z); +} + +/** + * gimp_vector3_inner_product_val: + * @vector1: the first #GimpVector3. + * @vector2: the second #GimpVector3. + * + * This function is identical to gimp_vector3_inner_product() but the + * vectors are passed by value rather than by reference. + * + * Returns: The inner product. + **/ +gdouble +gimp_vector3_inner_product_val (GimpVector3 vector1, + GimpVector3 vector2) +{ + return (vector1.x * vector2.x + + vector1.y * vector2.y + + vector1.z * vector2.z); +} + +/** + * gimp_vector3_cross_product: + * @vector1: a pointer to the first #GimpVector3. + * @vector2: a pointer to the second #GimpVector3. + * + * Compute the cross product of two vectors. The result is a + * #GimpVector3 which is orthogonal 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. + * + * Returns: The cross product. + **/ +GimpVector3 +gimp_vector3_cross_product (const GimpVector3 *vector1, + const GimpVector3 *vector2) +{ + GimpVector3 normal; + + normal.x = vector1->y * vector2->z - vector1->z * vector2->y; + normal.y = vector1->z * vector2->x - vector1->x * vector2->z; + normal.z = vector1->x * vector2->y - vector1->y * vector2->x; + + return normal; +} + +/** + * gimp_vector3_cross_product_val: + * @vector1: the first #GimpVector3. + * @vector2: the second #GimpVector3. + * + * This function is identical to gimp_vector3_cross_product() but the + * vectors are passed by value rather than by reference. + * + * Returns: The cross product. + **/ +GimpVector3 +gimp_vector3_cross_product_val (GimpVector3 vector1, + GimpVector3 vector2) +{ + GimpVector3 normal; + + normal.x = vector1.y * vector2.z - vector1.z * vector2.y; + normal.y = vector1.z * vector2.x - vector1.x * vector2.z; + normal.z = vector1.x * vector2.y - vector1.y * vector2.x; + + return normal; +} + +/** + * gimp_vector3_rotate: + * @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. + * + * 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. + **/ +void +gimp_vector3_rotate (GimpVector3 *vector, + gdouble alpha, + gdouble beta, + gdouble gamma) +{ + GimpVector3 s, t; + + /* First we rotate it around the Z axis (XY plane).. */ + /* ================================================= */ + + s.x = cos (alpha) * vector->x + sin (alpha) * vector->y; + s.y = cos (alpha) * vector->y - sin (alpha) * vector->x; + + /* ..then around the Y axis (XZ plane).. */ + /* ===================================== */ + + t = s; + + vector->x = cos (beta) *t.x + sin (beta) * vector->z; + s.z = cos (beta) *vector->z - sin (beta) * t.x; + + /* ..and at last around the X axis (YZ plane) */ + /* ========================================== */ + + vector->y = cos (gamma) * t.y + sin (gamma) * s.z; + vector->z = cos (gamma) * s.z - sin (gamma) * t.y; +} + +/** + * gimp_vector3_rotate_val: + * @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. + * + * This function is identical to gimp_vector3_rotate() but the vectors + * are passed by value rather than by reference. + * + * Returns: the rotated vector. + **/ +GimpVector3 +gimp_vector3_rotate_val (GimpVector3 vector, + gdouble alpha, + gdouble beta, + gdouble gamma) +{ + GimpVector3 s, t, result; + + /* First we rotate it around the Z axis (XY plane).. */ + /* ================================================= */ + + s.x = cos (alpha) * vector.x + sin (alpha) * vector.y; + s.y = cos (alpha) * vector.y - sin (alpha) * vector.x; + + /* ..then around the Y axis (XZ plane).. */ + /* ===================================== */ + + t = s; + + result.x = cos (beta) *t.x + sin (beta) * vector.z; + s.z = cos (beta) *vector.z - sin (beta) * t.x; + + /* ..and at last around the X axis (YZ plane) */ + /* ========================================== */ + + result.y = cos (gamma) * t.y + sin (gamma) * s.z; + result.z = cos (gamma) * s.z - sin (gamma) * t.y; + + return result; +} + +/** + * gimp_vector_2d_to_3d: + * @sx: the abscissa 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 abscissa 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. + * + * \"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) + **/ + +void +gimp_vector_2d_to_3d (gint sx, + gint sy, + gint w, + gint h, + gint x, + gint y, + const GimpVector3 *vp, + GimpVector3 *p) +{ + gdouble t = 0.0; + + if (vp->x != 0.0) + t = (p->z - vp->z) / vp->z; + + if (t != 0.0) + { + p->x = vp->x + t * (vp->x - ((gdouble) (x - sx) / (gdouble) w)); + p->y = vp->y + t * (vp->y - ((gdouble) (y - sy) / (gdouble) h)); + } + else + { + p->x = (gdouble) (x - sx) / (gdouble) w; + p->y = (gdouble) (y - sy) / (gdouble) h; + } +} + +/** + * gimp_vector_2d_to_3d_val: + * @sx: the abscissa 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 abscissa 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. + * + * 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. + * + * Returns: the computed #GimpVector3 point. + **/ +GimpVector3 +gimp_vector_2d_to_3d_val (gint sx, + gint sy, + gint w, + gint h, + gint x, + gint y, + GimpVector3 vp, + GimpVector3 p) +{ + GimpVector3 result; + gdouble t = 0.0; + + if (vp.x != 0.0) + t = (p.z - vp.z) / vp.z; + + if (t != 0.0) + { + result.x = vp.x + t * (vp.x - ((gdouble) (x - sx) / (gdouble) w)); + result.y = vp.y + t * (vp.y - ((gdouble) (y - sy) / (gdouble) h)); + } + else + { + result.x = (gdouble) (x - sx) / (gdouble) w; + result.y = (gdouble) (y - sy) / (gdouble) h; + } + + result.z = 0; + return result; +} + +/** + * gimp_vector_3d_to_2d: + * @sx: the abscissa 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 abscissa 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. + * + * 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(). + **/ +void +gimp_vector_3d_to_2d (gint sx, + gint sy, + gint w, + gint h, + gdouble *x, + gdouble *y, + const GimpVector3 *vp, + const GimpVector3 *p) +{ + gdouble t; + GimpVector3 dir; + + gimp_vector3_sub (&dir, p, vp); + gimp_vector3_normalize (&dir); + + if (dir.z != 0.0) + { + t = (-1.0 * vp->z) / dir.z; + *x = (gdouble) sx + ((vp->x + t * dir.x) * (gdouble) w); + *y = (gdouble) sy + ((vp->y + t * dir.y) * (gdouble) h); + } + else + { + *x = (gdouble) sx + (p->x * (gdouble) w); + *y = (gdouble) sy + (p->y * (gdouble) h); + } +} |