/*
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Open Asset Import Library - Java Binding (jassimp)
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*/
package jassimp;


/** 
 * Helper structure to describe a virtual camera.<p> 
 *
 * Cameras have a representation in the node graph and can be animated.
 * An important aspect is that the camera itself is also part of the
 * scenegraph. This means, any values such as the look-at vector are not 
 * *absolute*, they're <b>relative</b> to the coordinate system defined
 * by the node which corresponds to the camera. This allows for camera
 * animations. For static cameras parameters like the 'look-at' or 'up' vectors
 * are usually specified directly in aiCamera, but beware, they could also
 * be encoded in the node transformation. The following (pseudo)code sample 
 * shows how to do it: <p>
 * <code><pre>
 * // Get the camera matrix for a camera at a specific time
 * // if the node hierarchy for the camera does not contain
 * // at least one animated node this is a static computation
 * get-camera-matrix (node sceneRoot, camera cam) : matrix
 * {
 *    node   cnd = find-node-for-camera(cam)
 *    matrix cmt = identity()
 *
 *    // as usual - get the absolute camera transformation for this frame
 *    for each node nd in hierarchy from sceneRoot to cnd
 *      matrix cur
 *      if (is-animated(nd))
 *         cur = eval-animation(nd)
 *      else cur = nd->mTransformation;
 *      cmt = mult-matrices( cmt, cur )
 *    end for
 *
 *    // now multiply with the camera's own local transform
 *    cam = mult-matrices (cam, get-camera-matrix(cmt) )
 * }
 * </pre></code>
 *
 * <b>Note:</b> some file formats (such as 3DS, ASE) export a "target point" -
 * the point the camera is looking at (it can even be animated). Assimp
 * writes the target point as a subnode of the camera's main node,
 * called "<camName>.Target". However this is just additional information
 * then the transformation tracks of the camera main node make the
 * camera already look in the right direction.
 */
public final class AiCamera {
    /**
     * Constructor.
     * 
     * @param name name
     * @param position position
     * @param up up vector
     * @param lookAt look-at vector
     * @param horizontalFOV field of view
     * @param clipNear near clip plane
     * @param clipFar far clip plane
     * @param aspect aspect ratio
     */
    AiCamera(String name, Object position, Object up, Object lookAt, 
            float horizontalFOV, float clipNear, float clipFar, float aspect) {
        
        m_name = name;
        m_position = position;
        m_up = up;
        m_lookAt = lookAt;
        m_horizontalFOV = horizontalFOV;
        m_clipNear = clipNear;
        m_clipFar = clipFar;
        m_aspect = aspect;
    }


    /** 
     * Returns the name of the camera.<p>
     *
     *  There must be a node in the scenegraph with the same name.
     *  This node specifies the position of the camera in the scene
     *  hierarchy and can be animated.
     */
    public String getName() {
        return m_name;
    }
    

    /** 
     * Returns the position of the camera.<p>
     * 
     * The returned position is relative to the coordinate space defined by the
     * corresponding node.<p>
     *
     * The default value is 0|0|0.<p>
     * 
     * This method is part of the wrapped API (see {@link AiWrapperProvider}
     * for details on wrappers).<p>
     * 
     * The built-in behavior is to return a {@link AiVector}.
     * 
     * @param wrapperProvider the wrapper provider (used for type inference)
     * @return the position vector
     */
    @SuppressWarnings("unchecked")
    public <V3, M4, C, N, Q> V3 getPosition(AiWrapperProvider<V3, M4, C, N, Q> 
            wrapperProvider) {
        
        return (V3) m_position;
    }


    /** 
     * Returns the 'Up' - vector of the camera coordinate system.
     * 
     * The returned vector is relative to the coordinate space defined by the 
     * corresponding node.<p>
     *
     * The 'right' vector of the camera coordinate system is the cross product
     * of  the up and lookAt vectors. The default value is 0|1|0. The vector
     * may be normalized, but it needn't.<p>
     * 
     * This method is part of the wrapped API (see {@link AiWrapperProvider}
     * for details on wrappers).<p>
     * 
     * The built-in behavior is to return a {@link AiVector}.
     * 
     * @param wrapperProvider the wrapper provider (used for type inference)
     * @return the 'Up' vector
     */
    @SuppressWarnings("unchecked")
    public <V3, M4, C, N, Q> V3 getUp(AiWrapperProvider<V3, M4, C, N, Q> 
            wrapperProvider) {
    
        return (V3) m_up;
    }


    /** 
     * Returns the 'LookAt' - vector of the camera coordinate system.<p>
     * 
     * The returned vector is relative to the coordinate space defined by the 
     * corresponding node.<p>
     *
     * This is the viewing direction of the user. The default value is 0|0|1. 
     * The vector may be normalized, but it needn't.<p>
     * 
     * This method is part of the wrapped API (see {@link AiWrapperProvider}
     * for details on wrappers).<p>
     * 
     * The built-in behavior is to return a {@link AiVector}.
     * 
     * @param wrapperProvider the wrapper provider (used for type inference)
     * @return the 'LookAt' vector
     */
    @SuppressWarnings("unchecked")
    public <V3, M4, C, N, Q> V3 getLookAt(AiWrapperProvider<V3, M4, C, N, Q> 
            wrapperProvider) {
    
        return (V3) m_lookAt;
    }


    /** 
     * Returns the half horizontal field of view angle, in radians.<p> 
     *
     * The field of view angle is the angle between the center line of the 
     * screen and the left or right border. The default value is 1/4PI.
     * 
     * @return the half horizontal field of view angle
     */
    public float getHorizontalFOV() {
        return m_horizontalFOV;
    }

    
    /** 
     * Returns the distance of the near clipping plane from the camera.<p>
     *
     * The value may not be 0.f (for arithmetic reasons to prevent a division 
     * through zero). The default value is 0.1f.
     * 
     * @return the distance of the near clipping plane
     */
    public float getClipPlaneNear() {
        return m_clipNear;
    }
    

    /** 
     * Returns the distance of the far clipping plane from the camera.<p>
     *
     * The far clipping plane must, of course, be further away than the
     * near clipping plane. The default value is 1000.0f. The ratio
     * between the near and the far plane should not be too
     * large (between 1000-10000 should be ok) to avoid floating-point
     * inaccuracies which could lead to z-fighting.
     * 
     * @return the distance of the far clipping plane
     */
    public float getClipPlaneFar() {
        return m_clipFar;
    }


    /** 
     * Returns the screen aspect ratio.<p>
     *
     * This is the ration between the width and the height of the
     * screen. Typical values are 4/3, 1/2 or 1/1. This value is
     * 0 if the aspect ratio is not defined in the source file.
     * 0 is also the default value.
     * 
     * @return the screen aspect ratio
     */
    public float getAspect() {
        return m_aspect;
    }
    
    
    /**
     * Name.
     */
    private final String m_name;
    
    
    /**
     * Position.
     */
    private final Object m_position;
    
    
    /**
     * Up vector.
     */
    private final Object m_up;
    
    
    /**
     * Look-At vector.
     */
    private final Object m_lookAt;
    
    
    /**
     * FOV.
     */
    private final float m_horizontalFOV;
    
    
    /**
     * Near clipping plane.
     */
    private final float m_clipNear;
    
    
    /**
     * Far clipping plane.
     */
    private final float m_clipFar;
    
    
    /**
     * Aspect ratio.
     */
    private final float m_aspect;
}
