# GVRHeadTransform Class

[Instance Methods](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#pub-methods) GVRHeadTransform Class Reference

## Overview

Defines a class to represent the head transformation for a render frame.

Inherits NSObject.

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| ## Instance Method Summary ||
| (CGRect) | - [viewportForEye:](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#af2c7e7d1b17d19dfed25cb32446cafe4) |
|   | Returns the screen viewport for a given eye. [More...](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#af2c7e7d1b17d19dfed25cb32446cafe4) |
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| (GLKMatrix4) | - [projectionMatrixForEye:near:far:](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#a5767a6cac64dc0009f8fe998132d3460) |
|   | Returns the projection matrix for the specified eye. [More...](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#a5767a6cac64dc0009f8fe998132d3460) |
|   ||
| (GLKMatrix4) | - [eyeFromHeadMatrix:](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#adcc7f58c9b132adc9301436a8e0a3c9f) |
|   | Returns the transformation matrix used to convert from Head Space to Eye Space for the given eye. [More...](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#adcc7f58c9b132adc9301436a8e0a3c9f) |
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| (GLKMatrix4) | - [headPoseInStartSpace](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#abfb2547e525664b531b9263b9e3b6792) |
|   | Returns the reference matrix of the head pose in start space. [More...](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#abfb2547e525664b531b9263b9e3b6792) |
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| ([GVRFieldOfView](https://developers.google.com/vr/ios/reference/struct_g_v_r_field_of_view)) | - [fieldOfViewForEye:](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#a847a2cfcbcae0d66391fb6204b24f1a2) |
|   | Returns the field of view for the specified eye. [More...](https://developers.google.com/vr/ios/reference/interface_g_v_r_head_transform#a847a2cfcbcae0d66391fb6204b24f1a2) |
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## Method Detail

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| - (CGRect) viewportForEye: |   | (GVREye) | *eye* |   |

Returns the screen viewport for a given eye.

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| - (GLKMatrix4) projectionMatrixForEye: |   | (GVREye) | *eye* |
| near: |   | (CGFloat) | *near* |
| far: |   | (CGFloat) | *far* |
|   |   |   |   |

Returns the projection matrix for the specified eye.

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| - (GLKMatrix4) eyeFromHeadMatrix: |   | (GVREye) | *eye* |   |

Returns the transformation matrix used to convert from Head Space to Eye Space for the given eye.

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| - (GLKMatrix4) headPoseInStartSpace |   |   |   |

Returns the reference matrix of the head pose in start space.

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| - ([GVRFieldOfView](https://developers.google.com/vr/ios/reference/struct_g_v_r_field_of_view)) fieldOfViewForEye: |   | (GVREye) | *eye* |   |

Returns the field of view for the specified eye.