NAME

rendering_hints − provide rendering hints to increase rendering performance. 

SYNOPSIS

C Syntax:

void rendering_hints(fildes,hint_type,data)
int fildes,hint_type;
rend_hint_data *data;

FORTRAN77 Syntax:

subroutine rendering_hints(fildes,hint_type,data)
integer*4 fildes,hint_type
integer*4 data(64)
or
real data(64)
or
character data(255)

Pascal Syntax:

procedure rendering_hints(fildes,hint_type:integer;
data:rend_hint_data);

DESCRIPTION

Input Parameters

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

hint_type Type of hint to be given. 

data Data provided by this hint in hint-dependent format. 

Discussion

A hint and associated data are passed to Starbase for the purpose of increasing rendering performance.  The action taken for each hint may be device-dependent. 

In C, rend_hint_data is defined in <starbase.c.h> as:

typedef union {
int i[64];
float f[64];
char c[255];
} rend_hint_data:

In Pascal, rend_hint_data is defined in <starbase.p1.h> as:

rend_hint_data = record
case integer of
0: (i : array[1..64] of integer);
1: (f : array[1..64] of real);
2: (c : packed array[1..255] of char);
end;

Supported rendering hints

POLYGON_SHAPE_HINT This hint takes the following data values:

PG_SHAPE_COMPLEX
PG_SHAPE_CONVEX

The data is passed to rendering_hints in data.i[0].  PG_SHAPE_COMPLEX is the normal default mode.  It allows you to draw any-shaped polygons.  PG_SHAPE_CONVEX lets you tell Starbase that all of your polygons drawn while this mode is on will be convex.  This allows some drivers to use a faster algorithm for filling such polygons (note: not all drivers may take advantage of this hint).  Non-convex polygons drawn in PG_SHAPE_CONVEX mode will not be filled correctly.  Be careful with non-planar 3-D polygons when using the PG_SHAPE_CONVEX hint. Depending on the viewing matrix these can appear convex at some times and concave at other times.

Hewlett-Packard Company  —  HP-UX Release 9.0: August 1992