mutter/cogl/cogl-euler.h

270 lines
8.7 KiB
C
Raw Normal View History

/*
* Cogl
*
This re-licenses Cogl 1.18 under the MIT license Since the Cogl 1.18 branch is actively maintained in parallel with the master branch; this is a counter part to commit 1b83ef938fc16b which re-licensed the master branch to use the MIT license. This re-licensing is a follow up to the proposal that was sent to the Cogl mailing list: http://lists.freedesktop.org/archives/cogl/2013-December/001465.html Note: there was a copyright assignment policy in place for Clutter (and therefore Cogl which was part of Clutter at the time) until the 11th of June 2010 and so we only checked the details after that point (commit 0bbf50f905) For each file, authors were identified via this Git command: $ git blame -p -C -C -C20 -M -M10 0bbf50f905..HEAD We received blanket approvals for re-licensing all Red Hat and Collabora contributions which reduced how many people needed to be contacted individually: - http://lists.freedesktop.org/archives/cogl/2013-December/001470.html - http://lists.freedesktop.org/archives/cogl/2014-January/001536.html Individual approval requests were sent to all the other identified authors who all confirmed the re-license on the Cogl mailinglist: http://lists.freedesktop.org/archives/cogl/2014-January As well as updating the copyright header in all sources files, the COPYING file has been updated to reflect the license change and also document the other licenses used in Cogl such as the SGI Free Software License B, version 2.0 and the 3-clause BSD license. This patch was not simply cherry-picked from master; but the same methodology was used to check the source files.
2014-02-21 20:28:54 -05:00
* A Low Level GPU Graphics and Utilities API
*
* Copyright (C) 2010 Intel Corporation.
*
This re-licenses Cogl 1.18 under the MIT license Since the Cogl 1.18 branch is actively maintained in parallel with the master branch; this is a counter part to commit 1b83ef938fc16b which re-licensed the master branch to use the MIT license. This re-licensing is a follow up to the proposal that was sent to the Cogl mailing list: http://lists.freedesktop.org/archives/cogl/2013-December/001465.html Note: there was a copyright assignment policy in place for Clutter (and therefore Cogl which was part of Clutter at the time) until the 11th of June 2010 and so we only checked the details after that point (commit 0bbf50f905) For each file, authors were identified via this Git command: $ git blame -p -C -C -C20 -M -M10 0bbf50f905..HEAD We received blanket approvals for re-licensing all Red Hat and Collabora contributions which reduced how many people needed to be contacted individually: - http://lists.freedesktop.org/archives/cogl/2013-December/001470.html - http://lists.freedesktop.org/archives/cogl/2014-January/001536.html Individual approval requests were sent to all the other identified authors who all confirmed the re-license on the Cogl mailinglist: http://lists.freedesktop.org/archives/cogl/2014-January As well as updating the copyright header in all sources files, the COPYING file has been updated to reflect the license change and also document the other licenses used in Cogl such as the SGI Free Software License B, version 2.0 and the 3-clause BSD license. This patch was not simply cherry-picked from master; but the same methodology was used to check the source files.
2014-02-21 20:28:54 -05:00
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
This re-licenses Cogl 1.18 under the MIT license Since the Cogl 1.18 branch is actively maintained in parallel with the master branch; this is a counter part to commit 1b83ef938fc16b which re-licensed the master branch to use the MIT license. This re-licensing is a follow up to the proposal that was sent to the Cogl mailing list: http://lists.freedesktop.org/archives/cogl/2013-December/001465.html Note: there was a copyright assignment policy in place for Clutter (and therefore Cogl which was part of Clutter at the time) until the 11th of June 2010 and so we only checked the details after that point (commit 0bbf50f905) For each file, authors were identified via this Git command: $ git blame -p -C -C -C20 -M -M10 0bbf50f905..HEAD We received blanket approvals for re-licensing all Red Hat and Collabora contributions which reduced how many people needed to be contacted individually: - http://lists.freedesktop.org/archives/cogl/2013-December/001470.html - http://lists.freedesktop.org/archives/cogl/2014-January/001536.html Individual approval requests were sent to all the other identified authors who all confirmed the re-license on the Cogl mailinglist: http://lists.freedesktop.org/archives/cogl/2014-January As well as updating the copyright header in all sources files, the COPYING file has been updated to reflect the license change and also document the other licenses used in Cogl such as the SGI Free Software License B, version 2.0 and the 3-clause BSD license. This patch was not simply cherry-picked from master; but the same methodology was used to check the source files.
2014-02-21 20:28:54 -05:00
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
This re-licenses Cogl 1.18 under the MIT license Since the Cogl 1.18 branch is actively maintained in parallel with the master branch; this is a counter part to commit 1b83ef938fc16b which re-licensed the master branch to use the MIT license. This re-licensing is a follow up to the proposal that was sent to the Cogl mailing list: http://lists.freedesktop.org/archives/cogl/2013-December/001465.html Note: there was a copyright assignment policy in place for Clutter (and therefore Cogl which was part of Clutter at the time) until the 11th of June 2010 and so we only checked the details after that point (commit 0bbf50f905) For each file, authors were identified via this Git command: $ git blame -p -C -C -C20 -M -M10 0bbf50f905..HEAD We received blanket approvals for re-licensing all Red Hat and Collabora contributions which reduced how many people needed to be contacted individually: - http://lists.freedesktop.org/archives/cogl/2013-December/001470.html - http://lists.freedesktop.org/archives/cogl/2014-January/001536.html Individual approval requests were sent to all the other identified authors who all confirmed the re-license on the Cogl mailinglist: http://lists.freedesktop.org/archives/cogl/2014-January As well as updating the copyright header in all sources files, the COPYING file has been updated to reflect the license change and also document the other licenses used in Cogl such as the SGI Free Software License B, version 2.0 and the 3-clause BSD license. This patch was not simply cherry-picked from master; but the same methodology was used to check the source files.
2014-02-21 20:28:54 -05:00
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* 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_EULER_H
#define __COGL_EULER_H
#include <cogl/cogl-types.h>
#ifdef COGL_HAS_GTYPE_SUPPORT
#include <glib-object.h>
#endif
COGL_BEGIN_DECLS
/**
* SECTION:cogl-euler
* @short_description: Functions for initializing and manipulating
* euler angles.
*
* Euler angles are a simple representation of a 3 dimensional
* rotation; comprised of 3 ordered heading, pitch and roll rotations.
* An important thing to understand is that the axis of rotation
* belong to the object being rotated and so they also rotate as each
* of the heading, pitch and roll rotations are applied.
*
* One way to consider euler angles is to imagine controlling an
* aeroplane, where you first choose a heading (Such as flying south
* east), then you set the pitch (such as 30 degrees to take off) and
* then you might set a roll, by dipping the left, wing as you prepare
* to turn.
*
* They have some advantages and limitations that it helps to be
* aware of:
*
* Advantages:
* <itemizedlist>
* <listitem>
* Easy to understand and use, compared to quaternions and matrices,
* so may be a good choice for a user interface.
* </listitem>
* <listitem>
* Efficient storage, needing only 3 components any rotation can be
* represented.
* <note>Actually the #CoglEuler type isn't optimized for size because
* we may cache the equivalent #CoglQuaternion along with a euler
* rotation, but it would be trivial for an application to track the
* components of euler rotations in a packed float array if optimizing
* for size was important. The values could be passed to Cogl only when
* manipulation is necessary.</note>
* </listitem>
* </itemizedlist>
*
* Disadvantages:
* <itemizedlist>
* <listitem>
* Aliasing: it's possible to represent some rotations with multiple
* different heading, pitch and roll rotations.
* </listitem>
* <listitem>
* They can suffer from a problem called Gimbal Lock. A good
* explanation of this can be seen on wikipedia here:
* http://en.wikipedia.org/wiki/Gimbal_lock but basically two
* of the axis of rotation may become aligned and so you loose a
* degree of freedom. For example a pitch of +-90° would mean that
* heading and bank rotate around the same axis.
* </listitem>
* <listitem>
* If you use euler angles to orient something in 3D space and try to
* transition between orientations by interpolating the component
* angles you probably wont get the transitions you expect as they may
* not follow the shortest path between the two orientations.
* </listitem>
* <listitem>
* There's no standard to what order the component axis rotations are
* applied. The most common convention seems to be what we do in Cogl
* with heading (y-axis), pitch (x-axis) and then roll (z-axis), but
* other software might apply x-axis, y-axis then z-axis or any other
* order so you need to consider this if you are accepting euler
* rotations from some other software. Other software may also use
* slightly different aeronautical terms, such as "yaw" instead of
* "heading" or "bank" instead of "roll".
* </listitem>
* </itemizedlist>
*
* To minimize the aliasing issue we may refer to "Canonical Euler"
* angles where heading and roll are restricted to +- 180° and pitch is
* restricted to +- 90°. If pitch is +- 90° bank is set to 0°.
*
* Quaternions don't suffer from Gimbal Lock and they can be nicely
* interpolated between, their disadvantage is that they don't have an
* intuitive representation.
*
* A common practice is to accept angles in the intuitive Euler form
* and convert them to quaternions internally to avoid Gimbal Lock and
* handle interpolations. See cogl_quaternion_init_from_euler().
*/
/**
* CoglEuler:
* @heading: Angle to rotate around an object's y axis
* @pitch: Angle to rotate around an object's x axis
* @roll: Angle to rotate around an object's z axis
*
* Represents an ordered rotation first of @heading degrees around an
* object's y axis, then @pitch degrees around an object's x axis and
* finally @roll degrees around an object's z axis.
*
* <note>It's important to understand the that axis are associated
* with the object being rotated, so the axis also rotate in sequence
* with the rotations being applied.</note>
*
* The members of a #CoglEuler can be initialized, for example, with
* cogl_euler_init() and cogl_euler_init_from_quaternion ().
*
* You may also want to look at cogl_quaternion_init_from_euler() if
* you want to do interpolation between 3d rotations.
*
* Since: 2.0
*/
struct _CoglEuler
{
/*< public > */
float heading;
float pitch;
float roll;
/*< private > */
/* May cached a quaternion here in the future */
float padding0;
float padding1;
float padding2;
float padding3;
float padding4;
};
COGL_STRUCT_SIZE_ASSERT (CoglEuler, 32);
#ifdef COGL_HAS_GTYPE_SUPPORT
/**
* cogl_euler_get_gtype:
*
* Returns: a #GType that can be used with the GLib type system.
*/
GType cogl_euler_get_gtype (void);
#endif
/**
* cogl_euler_init:
* @euler: The #CoglEuler angle to initialize
* @heading: Angle to rotate around an object's y axis
* @pitch: Angle to rotate around an object's x axis
* @roll: Angle to rotate around an object's z axis
*
* Initializes @euler to represent a rotation of @x_angle degrees
* around the x axis, then @y_angle degrees around the y_axis and
* @z_angle degrees around the z axis.
*
* Since: 2.0
*/
void
cogl_euler_init (CoglEuler *euler,
float heading,
float pitch,
float roll);
/**
* cogl_euler_init_from_matrix:
* @euler: The #CoglEuler angle to initialize
* @matrix: A #CoglMatrix containing a rotation, but no scaling,
* mirroring or skewing.
*
* Extracts a euler rotation from the given @matrix and
* initializses @euler with the component x, y and z rotation angles.
*/
void
cogl_euler_init_from_matrix (CoglEuler *euler,
const CoglMatrix *matrix);
/**
* cogl_euler_init_from_quaternion:
* @euler: The #CoglEuler angle to initialize
* @quaternion: A #CoglEuler with the rotation to initialize with
*
* Initializes a @euler rotation with the equivalent rotation
* represented by the given @quaternion.
*/
void
cogl_euler_init_from_quaternion (CoglEuler *euler,
const CoglQuaternion *quaternion);
/**
* cogl_euler_equal:
* @v1: The first euler angle to compare
* @v2: The second euler angle to compare
*
* Compares the two given euler angles @v1 and @v1 and it they are
* equal returns %TRUE else %FALSE.
*
* <note>This function only checks that all three components rotations
* are numerically equal, it does not consider that some rotations
* can be represented with different component rotations</note>
*
* Returns: %TRUE if @v1 and @v2 are equal else %FALSE.
* Since: 2.0
*/
CoglBool
cogl_euler_equal (const void *v1, const void *v2);
/**
* cogl_euler_copy:
* @src: A #CoglEuler to copy
*
* Allocates a new #CoglEuler and initilizes it with the component
* angles of @src. The newly allocated euler should be freed using
* cogl_euler_free().
*
* Returns: A newly allocated #CoglEuler
* Since: 2.0
*/
CoglEuler *
cogl_euler_copy (const CoglEuler *src);
/**
* cogl_euler_free:
* @euler: A #CoglEuler allocated via cogl_euler_copy()
*
* Frees a #CoglEuler that was previously allocated using
* cogl_euler_copy().
*
* Since: 2.0
*/
void
cogl_euler_free (CoglEuler *euler);
COGL_END_DECLS
#endif /* __COGL_EULER_H */