## surfaces surfaces — Supports loading of .surf files and drawing of surfaces through OpenGL. |

## Synopsis

                        Surfaces;
    struct              SurfacesOrder_struct;
    typedef             SurfacesOrder;
    #define             VISU_ERROR_ISOSURFACES
    GQuark              isosurfacesGet_quark                (void);
    #define             ISOSURFACES_PROPERTY_POTENTIAL
    gboolean            isosurfacesGet_drawIntra            (void);
    gboolean            isosurfacesSet_drawIntra            (gboolean status);
    Surfaces*           isosurfacesNew                      (int bufferSize);
    void                isosurfacesAllocate                 (Surfaces *surf,
                                                             int nsurf,
                                                             int npolys,
                                                             int npoints);
    void                isosurfacesAddSurfaces              (Surfaces *surf,
                                                             int nsurf,
                                                             int npolys,
                                                             int npoints);
    void                isosurfacesFree                     (Surfaces *surf);
    gboolean            isosurfacesLoad_file                (const char *file,
                                                             Surfaces **surf,
                                                             GError **error);
    void                isoSurfacesSet_fitToBox             (VisuData *data,
                                                             Surfaces *surf);
    SurfacesOrder*      isosurfacesOrder_new                (void);
    void                isosurfacesOrder_free               (SurfacesOrder *order);
    int                 isosurfacesGet_nbSurfaces           (Surfaces *surf);
    const gchar*        isosurfacesGet_surfaceName          (Surfaces *surf,
                                                             int surf_index);
    gboolean            isosurfacesGet_surfaceRendered      (Surfaces *surf,
                                                             int surf_index);
    VisuSurfacesResources* isosurfacesGet_surfaceResource   (Surfaces *surf,
                                                             int surf_index);
    void                isosurfacesSet_surfaceResource      (Surfaces *surf,
                                                             int surf_index,
                                                             VisuSurfacesResources *res);
    int                 isosurfacesGet_surfaceId            (Surfaces *surf,
                                                             int i);
    int*                isosurfacesGet_surfaceSortedById    (Surfaces *surf);
    int                 isosurfacesGet_newId                (Surfaces *surf);
    int                 isosurfacesGet_surfacePosition      (Surfaces *surf,
                                                             int id);
    void                isosurfacesOrder_polygons           (SurfacesOrder *order,
                                                             Surfaces *surf[]);
    void                isosurfacesDraw_surfaces            (int openGLId,
                                                             Surfaces *surf[],
                                                             SurfacesOrder *order);
    void                isosurfacesDuplicate                (int totalList,
                                                             int simpleBlockList,
                                                             VisuData *dataObj,
                                                             gboolean reorder);
    void                isosurfacesSet_box                  (Surfaces *surf,
                                                             double box[6]);
    double*             isosurfacesGet_box                  (Surfaces *surf);
    float*              isosurfacesGet_floatProperty        (Surfaces *surf,
                                                             const gchar *name);
    float*              isosurfacesAdd_floatProperty        (Surfaces *surf,
                                                             const gchar *name);
    gboolean            isosurfacesGet_floatPropertyValue   (Surfaces *surf,
                                                             int idSurf,
                                                             const gchar *name,
                                                             float *value);
    gboolean            isosurfacesHide                     (Surfaces *surf,
                                                             Plane **planes);
    gboolean            isosurfacesRemove                   (Surfaces *surf,
                                                             int idSurf);
    void                isosurfacesCheck_consistency        (Surfaces *surf);
    void                isosurfacesInit                     (void);
    void                isosurfacesSet_showAll              (Surfaces *surf,
                                                             gboolean show);

## Description

Originally written by Luc Billard for his Visualize program. This module allows loading of .surf files to draw scalar fields on top of the current display scene. .surf files are text files which specs are the following :

- 1st line is arbitrary

- 2nd line must contain 3 real (float) values: dxx dyx dyy

- 3rd line must contain 3 real (float) values: dzx dzy dzz

- 4th line must contain 3 positive integers which represents respectively the number of surfaces, the total number of polys, and the total number of points

- Then, for each of these surfaces :

  - next line must contain the name of the surface : it is a string which should match the pattern surface_*

  - next line must contain 2 positive integer values: the number of polys (num_polys) and the number of points (num_points) used by the surface

  - each of the following num_polys lines must match the pattern [n i_1 i_2 i_3 ... i_n] where n is the number of vertices in the poly (n >= 3) and [i_1 i_2 i_3 ... i_n] are the numbering of these vertices (vertices numbered from 1 to num_points)

  - each of the following num_points lines must contain 6 real values for the successive (1 to num_points) points : [x y z nx ny nz], where x y z are the coordinates of the point and nx ny nz are the coordinates of the unit normal at the point

It is the responsibility of the user to guarantee that dxx, dyx, dyy, dzx, dzy, dzz match the one currently loaded in V_Sim's current context. Though if you use panelSurfaces you can ask to resize the surfaces so that they fit in the current loaded box.

## Details

### Surfaces

    typedef struct {
      /* Number of different surfaces. */
      int nsurf;

      SurfacesPoints basePoints;
      SurfacesPoints volatilePlanes;

      /* The description of the box where surfaces are drawn. */
      double local_box[6];

      /* Resources for each surfaces. */
      VisuSurfacesResources **resources;

      /* Id for each surfaces. */
      int *ids;

      /* Table to add properties to surfaces. */
      GHashTable *properties;
    } Surfaces;

This structure stores surfaces. Several surfaces are stored in a single structure for improved performences.

int `nsurf`; | number of surfaces encoded in this structure ;
SurfacesPoints `basePoints`; | the geometric description of surfaces.
SurfacesPoints `volatilePlanes`; | a storage for volatile polygons, .
double `local_box`[6]; | the description of the box where surfaces are drawn ;
VisuSurfacesResources **`resources`; | for each surface points on a VisuSurfacesResources ;
int *`ids`; | gives a list of ids used to index surfaces ;
GHashTable *`properties`; | an hashtable of properties.

### struct SurfacesOrder_struct

    struct SurfacesOrder_struct;

An opaque structure to store the order of drawn polygons when surfaces are involved.

### SurfacesOrder

    typedef struct SurfacesOrder_struct SurfacesOrder;

Short name to adress SurfacesOrder_struct objects.

### VISU_ERROR_ISOSURFACES

    #define VISU_ERROR_ISOSURFACES isosurfacesGet_quark()

### isosurfacesGet_quark ()

    GQuark              isosurfacesGet_quark                (void);

Internal routine for error handling.

Returns : | the GQuark associated to errors related to surface files.

### ISOSURFACES_PROPERTY_POTENTIAL

    #define ISOSURFACES_PROPERTY_POTENTIAL "potential_values"

Flag used in an ASCII surf file to give informations on the value the surface is built from.

### isosurfacesGet_drawIntra ()

    gboolean            isosurfacesGet_drawIntra            (void);

Retrieve if the interiors of surfaces are drawn with a colour inverse or not.

Returns : | TRUE if the interior is painted in colour inverse.

### isosurfacesSet_drawIntra ()

    gboolean            isosurfacesSet_drawIntra            (gboolean status);

Set if the interiors of surfaces are drawn with a colour inverse or not.

`status` : | a boolean.
Returns : | TRUE if calling routine should redraw the surfaces with `isosurfacesDraw_surfaces()`.

### isosurfacesNew ()

    Surfaces*           isosurfacesNew                      (int bufferSize);

Create a new (with unallocated internal arrays) structure to store surfaces. The buffer size is used to store other values than the position and the normal on each point.

`bufferSize` : | an integer.
Returns : | a newly allocated Surfaces structure.

### isosurfacesAllocate ()

    void                isosurfacesAllocate                 (Surfaces *surf,
                                                             int nsurf,
                                                             int npolys,
                                                             int npoints);

Allocate internal arrays to store surfaces having the given description.

`surf` : | a Surfaces structure ;
`nsurf` : | the number of surfaces to store ;
`npolys` : | the number of polygons (in total) ;
`npoints` : | the total number of vertices.

### isosurfacesAddSurfaces ()

    void                isosurfacesAddSurfaces              (Surfaces *surf,
                                                             int nsurf,
                                                             int npolys,
                                                             int npoints);

Change the allocation of internal arrays to store the additional surfaces with the given description.

`surf` : | a Surfaces structure ;
`nsurf` : | the number of surfaces to add ;
`npolys` : | the number of polygons to add ;
`npoints` : | the number of vertices to add.

### isosurfacesFree ()

    void                isosurfacesFree                     (Surfaces *surf);

Free all memory associated to the given surfaces.

`surf` : | a Surfaces structure.

### isosurfacesLoad_file ()

    gboolean            isosurfacesLoad_file                (const char *file,
                                                             Surfaces **surf,
                                                             GError **error);

This loads a surface file and set default material properties for it. See surf file specifications.

`file` : | target file to load ;
`surf` : | a set of surfaces (location) ;
`error` : | a location to store errors.
Returns : | TRUE in case of success, FALSE otherwise. Even in case of success `error` may have been set.

### isoSurfacesSet_fitToBox ()

    void                isoSurfacesSet_fitToBox             (VisuData *data,
                                                             Surfaces *surf);

This method changes the position of all vertices in the structure to match the box description given in `data`.

`data` : | a VisuData object ;
`surf` : | a set of surfaces.

### isosurfacesOrder_new ()

    SurfacesOrder*      isosurfacesOrder_new                (void);

Create an object to hold the order in which the surfaces must be drawn. See `isosurfacesOrder_polygons()` to set this object.

Returns : | a newly created SurfacesOrder object without any values.

### isosurfacesOrder_free ()

    void                isosurfacesOrder_free               (SurfacesOrder *order);

Free memory used by a SurfacesOrder object.

`order` : | the object to be freed.

### isosurfacesGet_nbSurfaces ()

    int                 isosurfacesGet_nbSurfaces           (Surfaces *surf);

Retrieves th number of surfaces stired in a given `surf` object.

`surf` : | the surface object.
Returns : | number of surfaces.

### isosurfacesGet_surfaceName ()

    const gchar*        isosurfacesGet_surfaceName          (Surfaces *surf,
                                                             int surf_index);

This returns for the given `surf_index` its name (1 <= surf_index <= surfaces_number)

`surf` : | the surface object ;
`surf_index` : | the number of the surface.
Returns : | the name of the surface or empty name or NULL, if `surf_index` is invalid.

### isosurfacesGet_surfaceRendered ()

    gboolean            isosurfacesGet_surfaceRendered      (Surfaces *surf,
                                                             int surf_index);

This returns for the given `surf_index` its visibility.

`surf` : | the surface object ;
`surf_index` : | the number of the surface.
Returns : | the visibility of the surface or FALSE, if `surf_index` is invalid.

### isosurfacesGet_surfaceResource ()

    VisuSurfacesResources* isosurfacesGet_surfaceResource   (Surfaces *surf,
                                                             int surf_index);

This returns for the given `surf_index` its resource information.

`surf` : | the surface object ;
`surf_index` : | the number of the surface.
Returns : | the resource of the surface or NULL, if `surf_index` is invalid.

### isosurfacesSet_surfaceResource ()

    void                isosurfacesSet_surfaceResource      (Surfaces *surf,
                                                             int surf_index,
                                                             VisuSurfacesResources *res);

This method is used to change the resource of a surface.

`surf` : | the surface object ;
`surf_index` : | the number of the surface ;
`res` : | the new resource.

### isosurfacesGet_surfaceId ()

    int                 isosurfacesGet_surfaceId            (Surfaces *surf,
                                                             int i);

This returns for the given `i` its id information.

`surf` : | the surface object ;
`i` : | the number of the surface.
Returns : | the id of the surface or 0, if `i` is invalid.

### isosurfacesGet_surfaceSortedById ()

    int*                isosurfacesGet_surfaceSortedById    (Surfaces *surf);

This returns the surface numbers sorted using their ids.

`surf` : | the surface object.
Returns : | a newly allocated array with surface numbers.

### isosurfacesGet_newId ()

    int                 isosurfacesGet_newId                (Surfaces *surf);

This returns a unique id to create a new surface.

`surf` : | the surface object.
Returns : | a value suitable to create a new surface in this set of surfaces.

### isosurfacesGet_surfacePosition ()

    int                 isosurfacesGet_surfacePosition      (Surfaces *surf,
                                                             int id);

This returns for the given `id` its number.

`surf` : | the surface object ;
`id` : | the id of the surface.
Returns : | the number of the surface or 0, if `id` is invalid.

### isosurfacesOrder_polygons ()

    void                isosurfacesOrder_polygons           (SurfacesOrder *order,
                                                             Surfaces *surf[]);

Re-orders the polygons in back to front order. This function should be called everytime a redraw is needed.

`order` : | the description of the polygons order ;
`surf` : | an array of Surfaces object, must be NULL terminated.

### isosurfacesDraw_surfaces ()

    void                isosurfacesDraw_surfaces            (int openGLId,
                                                             Surfaces *surf[],
                                                             SurfacesOrder *order);

Rebuild each visible surface's list. The order in which to draw the surfaces is given in the `order` argument. If the resource 'isosurfaces_drawIntra' is TRUE then, the interior of the surfaces is drawn as color inverse.

`openGLId` : | an id for the OpenGL list ;
`surf` : | an array of Surfaces object, must be NULL terminated.
`order` : | a SurfacesOrder object.

### isosurfacesDuplicate ()

    void                isosurfacesDuplicate                (int totalList,
                                                             int simpleBlockList,
                                                             VisuData *dataObj,
                                                             gboolean reorder);

Duplicate the list `simpleBlockList` using the extension of the given `dataObj`.

`totalList` : | an OpenGL identifier for the global list to create ;
`simpleBlockList` : | an OpenGL identifier for the list with the surfaces in the primitive cell ;
`dataObj` : | the corresponding VisuData object ;
`reorder` : | if TRUE the blocks are drawn from back to front.

### isosurfacesSet_box ()

    void                isosurfacesSet_box                  (Surfaces *surf,
                                                             double box[6]);

Copy the given `box` to the box of surfaces.

`surf` : | a Surfaces object ;
`box` : | a box definition in reduced coordinates.

### isosurfacesGet_box ()

    double*             isosurfacesGet_box                  (Surfaces *surf);

Get the box of the surfaces.

`surf` : | a Surfaces object.
Returns : | 6 floats, private, read-only.

### isosurfacesGet_floatProperty ()

    float*              isosurfacesGet_floatProperty        (Surfaces *surf,
                                                             const gchar *name);

Some properties can be associated to the surfaces stored in `surf`. This method is used to retrieve floating point values properties.

`surf` : | a Surfaces object ;
`name` : | the name of the property to look for.
Returns : | a table with the values if the property is found, NULL otherwise.

### isosurfacesAdd_floatProperty ()

    float*              isosurfacesAdd_floatProperty        (Surfaces *surf,
                                                             const gchar *name);

Some properties can be associated to the surfaces stored in `surf`. This method is add a new property.

`surf` : | a Surfaces object ;
`name` : | the name of the property to add.
Returns : | a newly allocated array that can be populated.

### isosurfacesGet_floatPropertyValue ()

    gboolean            isosurfacesGet_floatPropertyValue   (Surfaces *surf,
                                                             int idSurf,
                                                             const gchar *name,
                                                             float *value);

This method retrieves a float value stored as a property called `name` for the surface defined by its number `idSurf`.

`surf` : | a Surfaces object ;
`idSurf` : | a surface number ;
`name` : | the name of the property to get the value from ;
`value` : | a location to store the value.
Returns : | TRUE if a value is indeed found.

### isosurfacesHide ()

    gboolean            isosurfacesHide                     (Surfaces *surf,
                                                             Plane **planes);

Change the visibility of polygons stored in `surf`, following the masking scheme defined by the given list of `planes` (see Plane).

`surf` : | a Surfaces object ;
`planes` : | an array of planes (NULL terminated).
Returns : | TRUE if the surfaces should be rebuilt (see `isosurfacesDraw_surfaces()`).

### isosurfacesRemove ()

    gboolean            isosurfacesRemove                   (Surfaces *surf,
                                                             int idSurf);

Remove from memory all polygons from the given surface.

`surf` : | a Surfaces object ;
`idSurf` : | the id of the surf to remove.
Returns : | TRUE if the surface list is reduced to zero (and `surf` to be freed).

### isosurfacesCheck_consistency ()

    void                isosurfacesCheck_consistency        (Surfaces *surf);

Check if all arrays in the structures are consistent (without overflow).

`surf` : | a Surfaces object.

### isosurfacesInit ()

    void                isosurfacesInit                     (void);

Method used to initialised the surface handling, should not be called.

### isosurfacesSet_showAll ()

    void                isosurfacesSet_showAll              (Surfaces *surf,
                                                             gboolean show);

Shows or hides all surfaces and check their "draw" status in the panel accordingly.

`surf` : | a Surfaces object ;
`show` : | TRUE to show all surfaces, FALSE to hide them.