contour_enable(3G)

NAME

contour_enable − enable/disable contouring and set contouring type

SYNOPSIS

C Syntax:

void contour_enable(fildes,enable);
int fildes,enable;

FORTRAN77 Syntax:

subroutine contour_enable(fildes,enable)
integer*4 fildes,enable

Pascal Syntax:

procedure contour_enable(fildes,enable:integer);

DESCRIPTION

Input Parameters

fildes Integer file descriptor returned by gopen when an I/O path to a graphics device is opened.

enable The following flags are used to enable/disable contouring and to set the contouring style:

CONTOUR_LINE- enables contouring with contoured lines.
CONTOUR_SOLID- enables contouring with solid contour bands.
CONTOUR_SHADED - enables contouring with shaded contoured bands.
CONTOUR_OFF - disables contouring.

The second contour scalar value per vertex is used for backfacing facets when CONTOUR_BACKFACE is ORed with one of the constants above (CONTOUR_LINE, CONTOUR_SOLID, or CONTOUR_SHADED).

Discussion

contour_enable specifies whether or not polyhedron_with_data primitives or polygon_with_data3d primitives with contour data will be contoured. If enable is CONTOUR_OFF, these primitives are drawn in the current interior style without contouring. If enable is CONTOUR_LINE, CONTOUR_SOLID, or CONTOUR_SHADED, primitives in the form of triangular and/or quadrilateral facets are contoured using user-supplied per vertex scalar contour values. Per vertex scalar values are subsequently mapped to r,g,b values according to the defined contour table (see define_contour_table). Contouring a primitive supersedes the current interior_style except that the setting of the edge parameter is used to determine if edges are drawn. All other polygonal attributes apply to the contoured surfaces.

If enable is CONTOUR_LINE, then the contoured facets will be drawn with contour lines at each transition contour value defined in the contour table.

If enable is CONTOUR_SOLID, then the contoured facets will be drawn with solid contour bands between each transition contour value defined in the contour table.

If enable is CONTOUR_SHADED, then the contoured facets will be drawn with shaded contour bands by interpolating between the corresponding r,g,b colors for each transition contour value defined in the contour table.

If CONTOUR_BACKFACE is ORed with either CONTOUR_LINE, CONTOUR_SOLID, or CONTOUR_SHADED, the second contour scalar value per vertex is used for backfacing facets when backfacing polygon attributes are enabled through bf_control. If this flag is not specified, but backfacing polygonal attributes are enabled, the backfacing facet is rendering in the current backface polygonal attributes (i.e. no contouring occurs for the backfacing facet). If backfacing polygonal attributes are not enabled, the first contour value per vertex is used to contour the backfacing facet (i.e. no backface distinguishing occurs).

DEFAULTS

Contouring is off (CONTOUR_OFF).

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