// Creates a 2D roundover/bead mask shape that is useful for extruding into a 3D mask for an edge.
// Conversely, you can use that same extruded shape to make an interior fillet between two walls.
// As a 2D mask, this is designed to be differenced away from the edge of a shape that with its corner at the origin and one edge on the X+ axis and the other mask_angle degrees counterclockwise from the X+ axis.
// If called as a function, returns a 2D path of the outline of the mask shape.
// If you need roundings to agree on edges of different mask_angle, e.g. to round the base of a prismoid, then you need all of the
// masks used to have the same height. (Note that it may appear that matching joint would also work, but it does not because the joint distances are measured
// in different directions.) You can get the same height by setting the `height` parameter, which is an alternate way to control the size of the rounding.
// You can also set `quarter_round=true`, which creates a rounding that uses a quarter circle of the specified radius for all mask angles. If you have set inset
// you will need `flat_top=true` as well. Note that this is the default if you use `quarter_round=true` but not otherwise. Generally if you want a roundover
// results are best using the `height` option but if you want a bead as you get using `inset` the results are often best using the `quarter_round=true` option.
// Arguments:
// r = Radius of the roundover.
// inset = Optional bead inset size, perpendicular to the two edges. Scalar or 2-vector. Default: 0
// mask_angle = Number of degrees in the corner angle to mask. Default: 90
// excess = Extra amount of mask shape to creates on the X and quasi-Y sides of the shape. Default: 0.01
// ---
// d = Diameter of the roundover.
// h / height = Mask height excluding inset and excess. Give instead of r / d, cut or joint when you want a consistent mask height, no matter what the mask angle.
// cut = Cut distance. IE: How much of the corner to cut off. See [Types of Roundovers](rounding.scad#section-types-of-roundovers).
// joint = Joint distance. IE: How far from the edge the roundover should start. See [Types of Roundovers](rounding.scad#section-types-of-roundovers).
// flat_top = If true, the top inset of the mask will be horizontal instead of angled by the mask_angle. Default: true if quarter_round is set, false otherwise.
// quarter_round = If true, make a roundover independent of the mask_angle, defined based on a quarter circle of the specified size. Creates mask with angle-independent height. Default: false.
// anchor = Translate so anchor point is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
// Example(3D,Med,VPT=[25,30,12],VPR=[68,0,12],VPD=180): Using the quarter_round option results in a lip on obtuse angles, so it may not be the best choice for pure roundings.
// // Example(3D,Med,VPT=[25,30,12],VPR=[68,0,12],VPD=180): Can improve the quarter round option by using it only for acute angles and falling back on regular rounding for obtuse angles. Note that in this case, obtuse angles are fully rounded, but acute angles still have a corner, but one that is not as sharp as the original angle.
// Example(3D,Med,VPT=[25,30,12],VPR=[68,0,12],VPD=180): Bead may be more pleasing using the quarter_round option, with curves terminating in a plane parallel to the prismoid top. The size of the inset edge will be larger than requested when the angle is obtuse.
// Creates a 2D teardrop mask shape that is useful for extruding into a 3D mask for an edge.
// Conversely, you can use that same extruded shape to make an interior teardrop fillet between two walls.
// As a 2D mask, this is designed to be differenced away from the edge of a shape that with its corner at the origin and one edge on the X+ axis and the other mask_angle degrees counterclockwise from the X+ axis.
// If called as a function, returns a 2D path of the outline of the mask shape.
// This is particularly useful to make partially rounded bottoms, that don't need support to print.
// The roundover can be specified by radius, diameter, height, cut, or joint length.
// 
// Arguments:
// r = Radius of the rounding.
// angle = The angle from vertical of the flat section. Must be between mask_angle-90 and 90 degrees. Default: 45.
// Creates a 2D cove mask shape that is useful for extruding into a 3D mask for an edge.
// Conversely, you can use that same extruded shape to make an interior rounded shelf decoration between two walls.
// As a 2D mask, this is designed to be differenced away from the edge of a shape that with its corner at the origin and one edge on the X+ axis and the other mask_angle degrees counterclockwise from the X+ axis.
// If called as a function, returns a 2D path of the outline of the mask shape.
// .
// If you need coves to agree on edges of different mask_angle, e.g. on the top of a prismoid, then you need all of the
// masks used to have the same height. You can get the same height by setting the `height` parameter. For obtuse angles, however, the cove mask may not
// have is maximum height at the edge, which means it won't mate with adjacent coves. You can fix this using `flat_top=true` which extends the circle
// with a line to maintain a flat top. Another way to fix it is to set `bulge`. You can also achieve constant height using the `quarter_round=` option,
// which uses a quarter circle of the specified size for all mask_angle values. This option often produces a nice result because coves all terminate in a
// plane at 90 degrees.
// Arguments:
// r = Radius of the cove.
// inset = Optional amount to inset in the perpendicular direction from the edges. Scalar or 2-vector. Default: 0
// mask_angle = Number of degrees in the corner angle to mask. Default: 90
// excess = Extra amount of mask shape to creates on the X and quasi-Y sides of the shape. Default: 0.01
// ---
// d = Diameter of the cove.
// h / height = Mask height, excluding inset and excess. Given instead of r or d when you want a consistent mask height, no matter what the mask angle.
// bulge = specify arc as the distance away from a straight line chamfer. The arc will not meet the sides at a 90 deg angle.
// quarter_round = If true, make cove independent of the mask_angle, defined based on a quarter circle, with angle-independent radius. The mask will have constant height. Default: false.
// flat_top = If true, the top inset of the mask will be horizontal instead of angled by the mask_angle. In the case of obtuse angles force the mask to have a flat section at its left side instead of a circular arc. Default: true if quarter_round is set, false otherwise.
// anchor = Translate so anchor point is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
// Side Effects:
// Tags the children with "remove" (and hence sets `$tag`) if no tag is already set.
// Example(2D): 2D Cove Mask by Radius
// mask2d_cove(r=10);
// Example(2D): 2D Inset Cove Mask (not much different than a regular cove of larger radius)
// mask2d_cove(r=10,inset=3);
// Example(2D): 2D Cove Mask for acute angle, specified by height, with the bulge set to change the curve. Note that the circular arc is not perpendicular to the sides.
// mask2d_cove(h=10,mask_angle=55, bulge=3);
// Example(2D): 2D Cove Mask for obtuse angle, specified by height. This will produce an odd result if combined with other masks because the maximum height is in the middle.
// mask2d_cove(h=10,mask_angle=145);
// Example(2D): 2D Cove Mask for obtuse angle with flat top. This is one solution to the problem of the previous example. Max height is achieved at the left corner.
// Example(2D): 2D Cove Mask for obtuse angle, specified by height with bulge parameter. Another way to fix the problem of the previous example: the max height is again achieved at the left corner.
// Example(3D,Med): A cove on top of an extreme prismoid top by setting height and using flat_top mode. This creates **long** flat tops sections at obtuse angles.
// Creates a 2D chamfer mask shape that is useful for extruding into a 3D mask for an edge.
// Conversely, you can use that same extruded shape to make an interior chamfer between two walls.
// As a 2D mask, this is designed to be differenced away from the edge of a shape that with its corner at the origin and one edge on the X+ axis and the other mask_angle degrees counterclockwise from the X+ axis.
// If called as a function, returns a 2D path of the outline of the mask shape.
// The edge parameter specifies the length of the chamfer's slanted edge. The x parameter specifies the width. The y parameter
// specfies the length of the non-horizontal arm of the chamfer. The height specifies the height of the chamfer independent
// of angle. You can specify any combination of parameters that determines a chamfer geometry.
// Arguments:
// edge = The length of the edge of the chamfer.
// angle = The angle of the chamfer edge, away from vertical. Default: mask_angle/2.
// inset = Optional amount to inset perpendicular to each edge. Scalar or 2-vector. Default: 0
// mask_angle = Number of degrees in the corner angle to mask. Default: 90
// excess = Extra amount of mask shape to creates on the X- and Y- sides of the shape. Default: 0.01
// ---
// x = The width of the chamfer (joint distance in x direction)
// y = The set-back (joint distance) in the non-x direction of the chamfer.
// h / height = The height of the chamfer (excluding inset and excess).
// w/ width = The width of the chamfer (excluding inset and excess).
// quarter_round = If true, make a roundover independent of the mask_angle, defined based on a 90 deg angle, with a constant height. Default: false.
// flat_top = If true, the top inset of the mask will be horizontal instead of angled by the mask_angle. Default: true.
// anchor = Translate so anchor point is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
// Side Effects:
// Tags the children with "remove" (and hence sets `$tag`) if no tag is already set.
// Example(2D): 2D Chamfer Mask, at 45 deg by default
// mask2d_chamfer(x=10);
// Example(2D): 2D Chamfer Mask, at 30 deg (measured down from vertical)
// mask2d_chamfer(x=10,angle=30);
// Example(2D): 2D Chamfer Mask on an acute angle. The default chamfer angle is to produce a symmetric chamfer.
// mask2d_chamfer(x=10,mask_angle=45);
// Example(2D): 2D Chamfer Mask on an acute angle. Here we specify the angle of the chamfer
// mask2d_chamfer(x=10,mask_angle=45,angle=45);
// Example(2D): 2D Chamfer Mask specified by x and y length
// mask2d_chamfer(x=4,y=10);
// Example(2D): 2D Chamfer Mask specified by x and y length. The y length is along the top side of the chamfer, not parallel to the Y axis.
// mask2d_chamfer(x=4,y=5,mask_angle=44);
// Example(2D): 2D Chamfer Mask specified by width and height.
// mask2d_chamfer(w=4,h=5,mask_angle=44);
// Example(2D): 2D Chamfer Mask on obtuse angle, specifying x. The right tip is 10 units from the origin.
// mask2d_chamfer(x=10,mask_angle=127);
// Example(2D): 2D Chamfer Mask on obtuse angle, specifying width. The entire width is 10.
// mask2d_chamfer(w=10,mask_angle=127);
// Example(2D): 2D Chamfer Mask by edge
// mask2d_chamfer(edge=10);
// Example(2D): 2D Chamfer Mask by edge, acute case
// mask2d_chamfer(edge=10, mask_angle=44);
// Example(2D): 2D Chamfer Mask by edge, obtuse case
// mask2d_chamfer(edge=10, mask_angle=144);
// Example(2D): 2D Chamfer Mask by edge and angle
// mask2d_chamfer(edge=10, angle=30);
// Example(2D): 2D Chamfer Mask by edge and x
// mask2d_chamfer(edge=10, x=9);
// Example(2D): 2D Inset Chamfer Mask
// mask2d_chamfer(x=10, inset=2);
// Example(2D): 2D Inset Chamfer Mask on acute angle
// mask2d_chamfer(x=10, inset=2, mask_angle=77);
// Example(2D): 2D Inset Chamfer Mask on acute angle with flat top
// Example(3D,Med): Chamfering an extreme prismoid with a fixed chamfer angle. Note that a very large chamfer angle is required because of the large obtuse angles.
// Creates a 2D rabbet mask shape. When differenced away, this mask
// creates at the corner a rectanguler space of the specified size.
// This mask can be extruding into a 3D mask for an edge, or
// you can use that same extruded shape to make an interior shelf decoration between two walls.
// As a 2D mask, this is designed to be differenced away from the edge of a shape that with its corner at the origin and one edge on the X+ axis and the other mask_angle degrees counterclockwise from the X+ axis.
// If called as a function, returns a 2D path of the outline of the mask shape.
// Arguments:
// size = The size of the rabbet, either as a scalar or an [X,Y] list.
// mask_angle = Number of degrees in the corner angle to mask. Default: 90
// excess = Extra amount of mask shape to creates on the X and quasi-Y sides of the shape. Default: 0.01
// ---
// anchor = Translate so anchor point is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
// Side Effects:
// Tags the children with "remove" (and hence sets `$tag`) if no tag is already set.
// Example(2D): 2D Rabbet Mask
// mask2d_rabbet(size=10);
// Example(2D): 2D Asymmetrical Rabbet Mask
// mask2d_rabbet(size=[5,10]);
// Example(2D): 2D Mask for a acute angle edge
// mask2d_rabbet(size=10, mask_angle=75);
// Example(2D): 2D Mask for obtuse angle edge. If the obtuse angle is too large the rabbet will not fit. If that happens, you will need to increase the rabbet width.
// Creates a 2D dovetail mask shape that is useful for extruding into a 3D mask for a 90° edge.
// Conversely, you can use that same extruded shape to make an interior dovetail between two walls at a 90º angle.
// As a 2D mask, this is designed to be differenced away from the edge of a shape that with its corner at the origin and one edge on the X+ axis and the other mask_angle degrees counterclockwise from the X+ axis.
// If called as a function, returns a 2D path of the outline of the mask shape.
// Arguments:
// edge = The length of the edge of the dovetail.
// angle = The angle of the chamfer edge, away from vertical.
// shelf = The extra height to add to the inside corner of the dovetail. Default: 0
// inset = Optional amount to inset in perpendicular direction from each edge. Default: 0
// mask_angle = Number of degrees in the corner angle to mask. Default: 90
// excess = Extra amount of mask shape to creates on the X and quasi-Y sides of the shape. Default: 0.01
// ---
// width = The width of the dovetail (excluding any inset)
// height = The height of the dovetail (excluding any inset or shelf).
// flat_top = If true, the top inset of the mask will be horizontal instead of angled by the mask_angle. Default: true.
// anchor = Translate so anchor point is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
// Side Effects:
// Tags the children with "remove" (and hence sets `$tag`) if no tag is already set.
// Example(2D): 2D Dovetail Mask
// mask2d_dovetail(width=10,angle=14);
// Example(2D): 2D Dovetail Mask by height and slope. A slope of 1/6 is a common choice.
// mask2d_dovetail(height=20, slope=1/6);
// Example(2D): 2D Inset Dovetail Mask to make the dovetail wider
// Creates a 2D Ogee mask shape that is useful for extruding into a 3D mask for a 90° edge.
// Conversely, you can use that same extruded shape to make an interior ogee decoration between two walls at a 90º angle.
// As a 2D mask, this is designed to be differenced away from the edge of a shape that with its corner at the origin and one edge on the X+ axis and the other mask_angle degrees counterclockwise from the X+ axis.
// Since there are a number of shapes that fall under the name ogee, the shape of this mask is given as a pattern.
// Patterns are given as TYPE, VALUE pairs. ie: `["fillet",10, "xstep",2, "step",[5,5], ...]`. See Patterns below.
// If called as a function, returns a 2D path of the outline of the mask shape.
// .
// ### Patterns
// .
// Type | Argument | Description
// -------- | --------- | ----------------
// "step" | [x,y] | Makes a line to a point `x` right and `y` down.
// "xstep" | dist | Makes a `dist` length line towards X+.
// "ystep" | dist | Makes a `dist` length line towards Y-.
// "round" | radius | Makes an arc that will mask a roundover.
// "fillet" | radius | Makes an arc that will mask a fillet.
//
// Arguments:
// pattern = A list of pattern pieces to describe the Ogee.
// excess = Extra amount of mask shape to creates on the X- and Y- sides of the shape. Default: 0.01
// ---
// anchor = Translate so anchor point is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis after anchor. See [spin](attachments.scad#subsection-spin). Default: `0`
