Viewport Info

The viewport info global returns information about the state of Layout's OpenGL viewports. The data is read-only, but you can set the parameters using navigation and display commands.

Global Call

   LWViewportInfo *vpinfo;
   vpinfo = global( LWVIEWPORTINFO_GLOBAL, GFUSE_TRANSIENT );

   typedef struct st_LWViewportInfo {
        int             numViewports;
        int             (*type)  (int);
        unsigned int    (*flags) (int);
        void            (*pos)   (int, LWDVector);
        void            (*xfrm)  (int, double mat[9]);
        void            (*clip)  (int, double *hither, double *yon);
        void            (*rect)  (int, int *left, int *top, int *width, int *height);
        int             (*viewLevel)   (int);
        int             (*projection)  (int, LWDMatrix4 projection, LWDMatrix4 inverse_projection);
        int             (*modelview)   (int, LWDMatrix4 modelview, LWDMatrix4 inverse_modelview);
        int             (*project)     (int, LWDVector world, double *winx, double *winy, double *winz);
        int             (*unproject)   (int, double winx, double winy, double winz, LWDVector world);
        double          (*pixelSize)   (int, double pixels, LWDVector refpos);
        int             (*handleSize)  (int);
        double          (*gridSize)    (int);
        LWItemID        (*viewItem)    (int);
   } LWViewportInfo;

numViewports

The number of viewports visible in the Layout interface.

view = type( i )

The type of view in the i^th viewport. It will be one of the following:

LVVIEWT_NONE

LVVIEWT_TOP

LVVIEWT_BOTTOM

LVVIEWT_BACK

LVVIEWT_FRONT

LVVIEWT_RIGHT

LVVIEWT_LEFT

LVVIEWT_PERSPECTIVE

LVVIEWT_LIGHT

LVVIEWT_CAMERA

LVVIEWT_SCHEMATIC

flags = flags( i )

Returns a set of bit flags for the  i^th viewport. These can be any combination of the following. 

LWVIEWF_CENTER
LWVIEWF_WEIGHTSHADE
LWVIEWF_XRAY

pos(i, spot)

Fills the spot vector with the viewing position of the  i^th viewport.

xfrm( i, mat[9] )

Fills mat with a 3x3 transformation from viewport coordinates to world coordinates for the  i^th viewport. Note that from LW9.0, the vpinfo->projection() and vpinfo->modelview() functions should be preferred, as the vpinfo->xfrm() function may not produce correct results for non-perspective camera views.

clip( i, &hither, &yon )

Fills hither and yon with the near and far Z clipping distances for the  i^th viewport. 

rect( i, &left, &top, &width, &height )

Fills left, top, width and height with pixel coordinates of the  i^th viewport. 

level = viewLevel( i )

Returns the view level for the  i^th viewport. The returned value is one of the LWOVIS_* values.

result = projection( i, projection, inverse_projection )

Fills the matrices with the projection matrix and the inverse of the projection matrix for the   i^th viewport. It is safe to pass in NULL for either of the matrices. The matrices follow the OpenGL convention of m[column][row] with column vectors. Returns 1 if the asked for matrices were retrieved, 0 on failure which usually means that an inverse matrix was asked for for a matrix that could not be inverted.

result = modelview( i, modelview, inverse_modelview )

Fills the matrices with the modelview matrix and the inverse of the modelview matrix for the   i^th viewport. It is safe to pass in NULL for either of the matrices. The matrices follow the OpenGL convention of m[column][row] with column vectors. Returns 1 if the asked for matrices were retrieved, 0 on failure which usually means that an inverse matrix was asked for for a matrix that could not be inverted.

result = project( i, world, &winx, &winy, &winz )

Computes the projected position of the given world coordinates for the  i^th viewport. The computed winx and winy position is in pixels, relative to the upper-left corner of the viewport. Returns 1 if the projection was successful, 0 otherwise. Note that the resulting coordinates may fall outside of the viewport.

result = unproject( i, winx, winy, winz, world )

Computes the world coordinates of a given pixel position of the   i^th viewport. The winz value ranges from 0 for a spot on the near clipping plane, to 1 for a spot on the far clipping plane. Note that drawing on the near or far clipping plane may cause flickering due to floating point imprecision causing random clipping. Returns 1 if the projection was successful, 0 otherwise. Failure is typically caused by the viewport having a non-invertible modelview or projection matrix.

size = pixelSize( i, pixels, refpos )

Returns the world size of the given number of pixels at the reference position in world for the i^th viewport. A sphere with a diameter of the returned size, placed at the reference position, will have a diameter of approximately the given number of pixels when projected.

size = handleSize( i )

Returns the standard handle size for the i^th viewport, in pixels. This is the size used for example for drawing the translation and rotation tool handles.

size = gridSize( i )

Returns the size of the grid spacing for the i^th viewport, in metres.

item = viewItem( i )

For viewports which have a view through a scene item (LWVIEWT_LIGHT and LWVIEWT_CAMERA) the ID of the item is returned. Otherwise LWITEM_NULL is returned.