Arch rendering resolution management. More...

Collaboration diagram for Resolutions:

Files
file	units_resolution.scad
	An abstraction for arc rendering resolution control.

Functions
function	resolution_fn (r)
	Return facets number for the given arc radius. More...

function	resolution_fs ()
	Return minimum facets size. More...

function	resolution_fa (r)
	Return the minimum facets angle. More...

function	resolution_reduced ()
	Return the radius at which arc resolution will begin to degrade. More...

module	resolution_info (r)
	Output resolution information to the console for given radius. More...

function	resolution_facets (r)
	Return facet count used to render a radius. More...

function	resolution_facetsv (r)
	Return facet count information list used to render a radius. More...

Variables
	$resolution_mode = "fast"
	<string> Global special variable that configures the arc resolution mode.

	$resolution_value = 0
	<number> Global special variable for modes that use custom resolutions.

Detailed Description

Arch rendering resolution management.

Functions, global variables, and configuration presets to provide a common mechanism for managing arc rendering resolution. Specifically, the number of fragments/facets with which arcs (circles, spheres, and cylinders, etc.) are rendered in OpenSCAD.

Example

    include <units/units_resolution.scad>;
    base_unit_length = "in";
    // set resolution to 25 fpi
    $resolution_mode  = "fpi";
    $resolution_value = 25;
    // use radius length of 1 inch
    r = convert_length(1, "in");
    $fs=resolution_fs();
    $fa=resolution_fa( r );
    resolution_info( r );
    f = resolution_facets( r );
    echo(str("for r = ", r, " ", unit_length_name(), ", facets = ", f));

Result (base_unit_length = mm):

ECHO: "$resolution_mode = [fpi], $resolution_value = 25, base_unit_length = millimeter"
ECHO: "$fn = 0, $fa = 2.29183, $fs = 1.016"
ECHO: "resolution reduction at radius > 25.4 millimeter"
ECHO: "for radius = 25.4 millimeter facets limited to 158 by $fs=1.016 millimeter"
ECHO: "for r = 25.4 millimeter, facets = 158"

Result (base_unit_length = cm):

ECHO: "$resolution_mode = [fpi], $resolution_value = 25, base_unit_length = centimeter"
ECHO: "$fn = 0, $fa = 2.29183, $fs = 0.1016"
ECHO: "resolution reduction at radius > 2.54 centimeter"
ECHO: "for radius = 2.54 centimeter facets limited to 158 by $fs=0.1016 centimeter"
ECHO: "for r = 2.54 centimeter, facets = 158"

Result (base_unit_length = mil):

ECHO: "$resolution_mode = [fpi], $resolution_value = 25, base_unit_length = thousandth"
ECHO: "$fn = 0, $fa = 2.29183, $fs = 40"
ECHO: "resolution reduction at radius > 1000 thousandth"
ECHO: "for radius = 1000 thousandth facets limited to 158 by $fs=40 thousandth"
ECHO: "for r = 1000 thousandth, facets = 158"

Result (base_unit_length = in):

ECHO: "$resolution_mode = [fpi], $resolution_value = 25, base_unit_length = inch"
ECHO: "$fn = 0, $fa = 2.29183, $fs = 0.04"
ECHO: "resolution reduction at radius > 1 inch"
ECHO: "for radius = 1 inch facets limited to 158 by $fs=0.04 inch"
ECHO: "for r = 1 inch, facets = 158"

Function Documentation

function resolution_fa ( r )

Return the minimum facets angle.

Parameters

r	<decimal> The arc radius.

Returns: <decimal> Minimum facet angle to be assigned to $fa.

The result of this function can be assigned to the special variables $fa to render arcs.

function resolution_facets ( r )

Return facet count used to render a radius.

Parameters

r	<decimal> The arc radius.

Returns: <integer> The number of fragments/facets that will be used to render a radius given the current values for $fn, $fa, and $fs.

function resolution_facetsv ( r )

Return facet count information list used to render a radius.

Parameters

r	<decimal> The arc radius.

Returns: <list-3> A 3-tuple list of the form: [facets <integer>,limiter <string>,value <decimal>].

Where facets is the number of fragments/facets that will be used to render the radius given the current values for $fn, $fa, and $fs. limiter identifies the special variable that currently limits the facets, and value is the current value assigned to the limiter.

function resolution_fn ( r )

Return facets number for the given arc radius.

Parameters

r	<decimal> The arc radius.

Returns: <integer> The number of facets to be assigned to $fn.

The result of this function can be assigned to the special variables $fn to render arcs according to the resolution mode set by $resolution_mode and $resolution_value.

The following table shows the modes that require $resolution_value to be set prior to specifying the custom values used during resolution calculation.

$resolution_mode	$resolution_value sets	radius dependent
set	fixed value	no
upf	units per facet	yes
fpu	facets per unit	yes
fpi	facets per inch	yes

The following table has common resolution presets. Equivalent configuration can be obtained using $resolution_mode and $resolution_value as described in the preview table.

$resolution_mode	preset description	radius dependent
fast	fast rendering mode	no
low	low resolution	yes
medium	medium resolution	yes
high	high resolution	yes
50um	50 micron per facets	yes
100um	100 micron per facets	yes
200um	200 micron per facets	yes
300um	300 micron per facets	yes
400um	400 micron per facets	yes
500um	500 micron per facets	yes
50mil	50 thousandth per facets	yes
100mil	100 thousandth per facets	yes
200mil	200 thousandth per facets	yes
300mil	300 thousandth per facets	yes
400mil	400 thousandth per facets	yes
500mil	500 thousandth per facets	yes

function resolution_fs ( )

Return minimum facets size.

Returns: <integer> Minimum facet size to be assigned to $fs.

The result of this function can be assigned to the special variables $fs to render arcs according to the resolution mode set by $resolution_mode and $resolution_value.

The following table shows the modes that require $resolution_value to be set prior to calling this function in order to specify the custom values used during resolution calculation.

$resolution_mode	$resolution_value sets	radius dependent
set	fixed value	no
upf	units per facet	no
fpu	facets per unit	no
fpi	facets per inch	no

The following table has common resolution presets. Equivalent configuration can be obtained using $resolution_mode and $resolution_value as described in the preview table.

$resolution_mode	preset description	radius dependent
fast	fast rendering mode	no
low	low resolution	no
medium	medium resolution	no
high	high resolution	no
50um	50 micron per facets	no
100um	100 micron per facets	no
200um	200 micron per facets	no
300um	300 micron per facets	no
400um	400 micron per facets	no
500um	500 micron per facets	no
50mil	50 thousandth per facets	no
100mil	100 thousandth per facets	no
200mil	200 thousandth per facets	no
300mil	300 thousandth per facets	no
400mil	400 thousandth per facets	no
500mil	500 thousandth per facets	no

module resolution_info ( r )

Output resolution information to the console for given radius.

Parameters

r	<decimal> The arc radius.

Definition at line 322 of file units_resolution.scad.

Here is the call graph for this function:

function resolution_reduced ( )

Return the radius at which arc resolution will begin to degrade.

Returns: <decimal> Transition radius where resolution reduction begins.

The special variables $fs and $fa work together when $fn = 0. For a given $fs, the fragment angle of a drawn arc gets smaller with increasing radius. In other words, the fragment angle is inversely proportional to the arc radius for a given fragment size.

The special variable $fa enforces a minimum fragment angle limit and at some radius, the fragment angle would becomes smaller than this limit. At this point, OpenSCAD limits further reduction in the facet angle which forces the use of increased fragment size. This in effect begins the gradual reduction of arc resolution with increasing radius.

The return result of this function indicates the radius at which this enforced limiting begins. When $fn != 0, returns undef.

Here is the caller graph for this function:

Files

Functions

Variables

Detailed Description

Function Documentation