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 back-facing 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, then the second contour scalar value per vertex is used for back-facing facets when back-facing polygon attributes are enabled through bf_control. If this flag is not specified, but back-facing polygonal attributes are enabled, the back-facing facet is rendering in the current back-face polygonal attributes (i.e. no contouring occurs for the back-facing facet). If back-facing polygonal attributes are not enabled, the first contour value per vertex is used to contour the back-facing facet (i.e. no back-face distinguishing occurs).

DEFAULTS

Contouring is off (CONTOUR_OFF).

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