Documentation for vtkViewRays

vtkViewRays - provides view ray information for efficiently casting rays

Description:

The vtkViewRays class calculates and stores the relevant information necessary to efficiently render perspective or parallel viewing rays. View rays are typically used by a ray caster where a view ray is cast per pixel in the requested image. The number of view rays requested in both X and Y is specified by the SetSize() method. The camera model used to create the view ray information is specified by the SetRenderer() method. Both the SetSize() and SetRenderer() method must be called before viewing ray information can be requested. vtkViewRays will recompute view ray information should the critical information in the camera, the renderer or number of rays change. vtkViewRays contains view ray information in view coordinates for either parallel or perspective viewing transformations. This reduces the computational burden on a ray caster since the computation of perspective, normalized viewing ray vectors is pre-computed once rather than during each rendering. When the camera viewing transform is perspective the start of each viewing vector (eye point) is fixed, but the direction of each ray varies. Therefore, vtkViewRays contains a 2D array of 3D unit vectors each representing the direction of a view ray with respect to the viewing coordinate system. A pointer to this 2D array of vectors is obtained by calling the GetPerspectiveViewRays() method. When the camera viewing transform is parallel the start of each viewing vector varies across the viewing plane but the direction remains constant. Since the starting point of each view ray can be captured by regularly sampling the parallel viewing plane, a 2D array of starting view ray positions is NOT used. Instead, the first view ray position (bottom left corner of view) is returned by the GetParallelStartPosition() method and the X and Y distance increments to the next view ray starting position are returned by the GetParallelIncrements() method.

Methods:

	void vtkViewRays ()
	void vtkViewRays ()
	static vtkViewRays *New ()
	const char *GetClassName ()
	void PrintSelf (unknown & ,vtkIndent )
	void SetRenderer (vtkRenderer *)
	vtkRenderer *GetRenderer ()
	void SetSize (int ,int )
	void SetSize (int *)
	int *GetSize ()
	float *GetPerspectiveViewRays ()
	float *GetParallelStartPosition ()
	float *GetParallelIncrements ()
	void ComputeParallelInfo (int )
	void ComputePerspectiveInfo (float * ,int )

Detailed Method Descriptions:

Specify the vtkRenderer whose camera will be used to to calculate the view rays. The type of camera (parallel, perspective) will determine which type of view ray information is calculated. Note: this does not increase the reference count of the renderer.

	void SetRenderer (vtkRenderer *)
	vtkRenderer *GetRenderer ()

Set the image size for the view rays.

	void SetSize (int ,int )
	void SetSize (int *)
	int *GetSize ()

Retrieve the 2D array of normalized view ray vectors formatted as 3 floats per vector (dx,dy,dz). This method is only valid after the SetSize() and SetRenderer() methods have been called.

float *GetPerspectiveViewRays ()

Retrieve the position of the bottom left ray

float *GetParallelStartPosition ()

Retrieve the distance to the next ray starting point along the X and Y direction.

float *GetParallelIncrements ()