arrow_ornaments {ggarrow}

Arrow ornament functions

Description

There are two types of arrow ornament functions: functions for arrow heads, and functions for arrow fins. The heads and fins can be used interchangeably, but the name makes it clearer what is suitable.

Usage

arrow_head_wings(offset = 20, inset = 30)

arrow_fins_feather(indent = 0.3, outdent = indent, height = 0.5)

arrow_head_line(angle = 30, lineend = "butt")

arrow_fins_line(angle = 30, lineend = "butt")

arrow_cup(lineend = "round", angle = NULL)

arrow_head_minimal(angle = 45)

arrow_fins_minimal(angle = 45)

Arguments

offset, angle

A numeric(1) giving an angle in degrees for the angle between the line and tip.

inset

A numeric(1) giving an angle in degrees for the angle inside the tip of the arrowhead.

indent, outdent

A numeric(1) giving the fraction of the feather feather length to offset the notch and the end respectively.

height

A numeric(1) ratio between the length of the feathers and the height of the feathers.

lineend

A character(1), one of "butt", "square", "round" or "parallel". For arrow_cup(), only "butt" and "round" are allowed.

Details

The convention for these functions is that the arrow shaft is fused to the ornament at the (0,0) point and the ornaments ends at the (1,0) point.

Value

A ⁠<matrix[n, 2]>⁠ with x and y columns describing a polygon. It has a notch_angle attribute that is used fusing the fins/head to the shaft of the arrow. They can be given to an arrow plotting function.

Functions

• arrow_head_wings(): Places two triangles at either side of the line. Let ABC be a triangle, where A is at the end of the line, B is on the line and C is the arrow wingtip. Then offset is the angle at corner A and inset is the angle at corner C.

• arrow_fins_feather(): Places trapezoids at either side of the line. Let ABCD be a quadrilateral shape, where A is at the end of the line, B is on the line, and CD is parallel to AB, but offset from the line. Then, indent is the distance along the line between A and D and outdent is the distance along the line between B and C.

• arrow_head_line(): A line as an arrow head.

• arrow_fins_line(): A line as an arrow fin.

• arrow_cup(): A curved line some fixed distance away from the point to be resected, resembling a 'cup' shape.

• arrow_head_minimal(): This is a 'fake' arrow head who in practice doesn't draw anything, but sets the notch_angle attribute such that the arrow shaft is whittled into a triangular point.

• arrow_fins_minimal(): This is a 'fake' arrow head who in practise doesn't draw anything, but sets the notch_angle attribute such that a triangle is taken out of the arrow shaft.

Examples

# Plotting winged head
plot(c(-0.5, 1), c(-0.6, 0.6), type = "n")
polygon(arrow_head_wings(), col = "gray")

# Plotting feather fins
plot(c(0, 1), c(-0.25, 0.25), type = "n")
polygon(arrow_fins_feather(), col = "gray")