54 \brief The QRotationReading class represents one reading from the |
54 \brief The QRotationReading class represents one reading from the |
55 rotation sensor. |
55 rotation sensor. |
56 |
56 |
57 \section2 QRotationReading Units |
57 \section2 QRotationReading Units |
58 |
58 |
59 The rotation reading contains 3 angles, measured in degrees that define the orientation |
59 The rotation reading contains 3 angles, measured in degrees that define |
60 of the device in three-dimensional space. The three angles are applied to the device in the |
60 the orientation of the device in three-dimensional space. The rotations |
61 following order. |
61 should not be confused with relative rotations such as yaw and pitch. |
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62 These rotations are of the devices axes relative to the external |
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63 reference points that define the reference co-ordinate axes: X, Y and Z |
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64 in the diagram. |
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65 |
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66 The three angles are applied to the device in the following order. |
62 |
67 |
63 \list |
68 \list |
64 \o Right-handed rotation z (-180, 180]. Starting from the x axis and incrementing towards the |
69 \o Right-handed rotation z (-180, 180]. Starting from the x-axis and |
65 y axis. |
70 incrementing in the direction of the y-axis. |
66 \o Right-handed rotation x (-90, 90]. Starting from the new (once-rotated) y axis and |
71 \o Right-handed rotation x [-90, 90]. Starting from the new |
67 incrementing towards the z axis. |
72 (once-rotated) y-axis and incrementing towards the z-axis. |
68 \o Right-handed rotation y (-180, 180]. Starting from the new (twice-rotated) z axis and |
73 \o Right-handed rotation y (-180, 180]. Starting from the new |
69 incrementing towards the x axis. |
74 (twice-rotated) z-axis and incrementing towards the x-axis. |
70 \endlist |
75 \endlist |
71 |
76 |
72 \image Rotation_angles.png Visual representation of the rotation angles. |
77 \image Rotation_angles.png Visual representation of the rotation angles. |
73 |
78 |
74 The 0 point for the z angle is defined as a fixed, external entity and is device-specific. While magnetic |
79 The 0 point for the z angle is defined as a fixed, external entity and |
75 north is typically used as this reference point it may not be. Do not attempt to compare values |
80 is device-specific. While magnetic North is typically used as this |
76 for the z angle between devices or even on the same device if it has moved a significant distance. |
81 reference point it may not be. Do not attempt to compare values |
77 If the device cannot detect a fixed, external entity the z angle will always be 0 and the |
82 for the z angle between devices or even on the same device if it has |
78 QRotationSensor::hasZ property will be set to false. |
83 moved a significant distance. |
79 |
84 |
80 The 0 point for the x and y angles are defined as when the x and y axes of the device are oriented |
85 If the device cannot detect a fixed, external entity the z angle will |
81 towards the horizon. |
86 always be 0 and the QRotationSensor::hasZ property will be set to false. |
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87 |
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88 The 0 point for the x and y angles are defined as when the x and y axes |
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89 of the device are oriented towards the horizon. |
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90 |
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91 Note that when x is 90 or -90, values for z and y achieve rotation around |
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92 the same axis (due to the order of operations). In this case the y |
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93 rotation will be 0. |
82 */ |
94 */ |
83 |
95 |
84 /*! |
96 /*! |
85 \property QRotationReading::x |
97 \property QRotationReading::x |
86 \brief the rotation around the x axis. |
98 \brief the rotation around the x axis. |