mutter/cogl/cogl-vector.h

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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2008,2009,2010 Intel Corporation.
*
* 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 2 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, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Authors:
* Robert Bragg <robert@linux.intel.com>
*/
#if !defined(__COGL_H_INSIDE__) && !defined(COGL_COMPILATION)
#error "Only <cogl/cogl.h> can be included directly."
#endif
#ifndef __COGL_VECTOR_H
#define __COGL_VECTOR_H
COGL_BEGIN_DECLS
/**
* SECTION:cogl-vector
* @short_description: Functions for handling single precision float
* vectors.
*
* This exposes a utility API that can be used for basic manipulation of 3
* component float vectors.
*/
/**
* cogl_vector3_init:
* @vector: The 3 component vector you want to initialize
* @x: The x component
* @y: The y component
* @z: The z component
*
* 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: Unstable
*/
void
cogl_vector3_init (float *vector, float x, float y, float z);
/**
* cogl_vector3_init_zero:
* @vector: The 3 component vector you want to initialize
*
* Initializes a 3 component, single precision float vector with zero
* for each component.
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_init_zero (float *vector);
/**
* cogl_vector3_equal:
* @v1: The first 3 component vector you want to compare
* @v2: The second 3 component vector you want to compare
*
* 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.
*
* Returns: TRUE if the vectors are equal else FALSE.
*
* Since: 1.4
* Stability: Unstable
*/
CoglBool
cogl_vector3_equal (const void *v1, const void *v2);
/**
* cogl_vector3_equal_with_epsilon:
* @vector0: The first 3 component vector you want to compare
* @vector1: The second 3 component vector you want to compare
* @epsilon: The allowable difference between components to still be
* considered equal
*
* 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:
* |[
* if (fabsf (vector0->x - vector1->x) < epsilon)
* ]|
*
* Returns: TRUE if the vectors are equal else FALSE.
*
* Since: 1.4
* Stability: Unstable
*/
CoglBool
cogl_vector3_equal_with_epsilon (const float *vector0,
const float *vector1,
float epsilon);
/**
* cogl_vector3_copy:
* @vector: The 3 component vector you want to copy
*
* 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()
*
* Returns: A newly allocated 3 component float vector
*
* Since: 1.4
* Stability: Unstable
*/
float *
cogl_vector3_copy (const float *vector);
/**
* cogl_vector3_free:
* @vector: The 3 component you want to free
*
* Frees a 3 component vector that was previously allocated with
* cogl_vector_copy()
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_free (float *vector);
/**
* cogl_vector3_invert:
* @vector: The 3 component vector you want to manipulate
*
* Inverts/negates all the components of the given @vector.
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_invert (float *vector);
/**
* cogl_vector3_add:
* @result: Where you want the result written
* @a: The first vector operand
* @b: The second vector operand
*
* Adds each of the corresponding components in vectors @a and @b
* storing the results in @result.
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_add (float *result,
const float *a,
const float *b);
/**
* cogl_vector3_subtract:
* @result: Where you want the result written
* @a: The first vector operand
* @b: The second vector operand
*
* Subtracts each of the corresponding components in vector @b from
* @a storing the results in @result.
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_subtract (float *result,
const float *a,
const float *b);
/**
* cogl_vector3_multiply_scalar:
* @vector: The 3 component vector you want to manipulate
* @scalar: The scalar you want to multiply the vector components by
*
* Multiplies each of the @vector components by the given scalar.
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_multiply_scalar (float *vector,
float scalar);
/**
* cogl_vector3_divide_scalar:
* @vector: The 3 component vector you want to manipulate
* @scalar: The scalar you want to divide the vector components by
*
* Divides each of the @vector components by the given scalar.
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_divide_scalar (float *vector,
float scalar);
/**
* cogl_vector3_normalize:
* @vector: The 3 component vector you want to manipulate
*
* Updates the vector so it is a "unit vector" such that the
* @vector<!-- -->s magnitude or length is equal to 1.
*
* <note>It's safe to use this function with the [0, 0, 0] vector, it will not
* try to divide components by 0 (its norm) and will leave the vector
* untouched.</note>
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_normalize (float *vector);
/**
* cogl_vector3_magnitude:
* @vector: The 3 component vector you want the magnitude for
*
* Calculates the scalar magnitude or length of @vector.
*
* Returns: The magnitude of @vector.
*
* Since: 1.4
* Stability: Unstable
*/
float
cogl_vector3_magnitude (const float *vector);
/**
* cogl_vector3_cross_product:
* @result: Where you want the result written
* @u: Your first 3 component vector
* @v: Your second 3 component vector
*
* 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.
*
* Returns: The cross product between two vectors @u and @v.
*
* Since: 1.4
* Stability: Unstable
*/
void
cogl_vector3_cross_product (float *result,
const float *u,
const float *v);
/**
* cogl_vector3_dot_product:
* @a: Your first 3 component vector
* @b: Your second 3 component vector
*
* 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.
*
* <note>If you don't use a unit length normal in the above example
* then you would then also have to divide the result by the magnitude
* of the normal</note>
*
* The dot product is calculated as:
* |[
* (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:
* |[
* |a||b|cos𝜃
* ]|
*
* Returns: The dot product of two vectors.
*
* Since: 1.4
* Stability: Unstable
*/
float
cogl_vector3_dot_product (const float *a, const float *b);
/**
* cogl_vector3_distance:
* @a: The first point
* @b: The second point
*
* If you consider the two given vectors as (x,y,z) points instead
* then this will compute the distance between those two points.
*
* Returns: The distance between two points given as 3 component
* vectors.
*
* Since: 1.4
* Stability: Unstable
*/
float
cogl_vector3_distance (const float *a, const float *b);
COGL_END_DECLS
#endif /* __COGL_VECTOR_H */