//
//  VROARCamera.h
//  ViroKit
//
//  Created by Raj Advani on 6/6/17.
//  Copyright © 2017 Viro Media. All rights reserved.
//

#ifndef VROARCamera_h
#define VROARCamera_h

#include <stdio.h>

class VROViewport;
class VROMatrix4f;
class VROVector3f;
class VROFieldOfView;

enum class VROARTrackingState {
    Unavailable,
    Limited,
    Normal,
};

/*
 Provides reasons for why we are in Limited tracking state.
 */
enum class VROARTrackingStateReason {
    None,
    ExcessiveMotion,
    InsufficientFeatures
};

/*
 Contains information about the current camera position and imaging
 characteristics. Updated periodically by the VROARSession.
 */
class VROARCamera {
public:
    
    VROARCamera() {}
    virtual ~VROARCamera() {}
    
    /*
     Get the quality of the tracking. If we are in limited tracking state,
     getLimitedTrackingStateReason() will return the reason for this state.
     */
    virtual VROARTrackingState getTrackingState() const = 0;
    virtual VROARTrackingStateReason getLimitedTrackingStateReason() const = 0;
    
    /*
     Get the position and rotation of the user in world space. These values
     are derived from the AR camera's extrinsic matrix, acquired via visual and
     inertial algorithms. They can be used to construct the view matrix for the
     renderer.
     */
    virtual VROMatrix4f getRotation() const = 0;
    virtual VROVector3f getPosition() const = 0;
    
    /*
     Get the projection matrix needed to render a 3D scene to match the image
     captured by this AR camera. The returned matrix is a concatenation of the
     AR camera's intrinsic matrix (3D space --> 2D space) and the renderer's
     orthographic projection matrix (2D space --> normalized device space).
     This function should also output the field of view in the provided output
     variable.
     */
    virtual VROMatrix4f getProjection(VROViewport viewport, float near, float far, VROFieldOfView *outFOV) const = 0;
    
    /*
     Get the image size (width, height) for the camera. Stored in the
     vector's x and y components.
     */
    virtual VROVector3f getImageSize() const = 0;
    
};

#endif /* VROARCamera_h */