## Generated by Codox

# Walkmap 0.1.0-SNAPSHOT

# walkmap.edge

Essentially the specification for things we shall consider to be an edge. An edge is a line segment having just a start and an end, with no intervening nodes.

### centre

`(centre edge)`

Return the vertex that represents the centre of this `edge`.

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### collinear2d?

`(collinear2d? e1 e2)`

True if the projections of edges `e1`, `e2` onto the x, y plane are collinear.

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### collinear?

`(collinear? e1 e2)`

True if edges `e1` and `e2` are collinear with one another.

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### edge

`(edge v1 v2)`

Return an edge between vertices `v1` and `v2`.

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### edge?

`(edge? o)`

True if `o` satisfies the conditions for a edge. An edge shall be a map having the keys `:start` and `:end`, such that the values of each of those keys shall be a vertex.

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### intersection2d

`(intersection2d e1 e2)`

The probability of two lines intersecting in 3d space is low, and actually that is mostly not something we’re interested in. We’re interested in intersection in the `x,y` plane. This function returns a vertex representing a point vertically over the intersection of edges `e1`, `e2` in the `x,y` plane, whose `z` coordinate is

- 0 if both edges are 2d (i.e. have missing or zero `z` coordinates);
- if one edge is 2d, then the point on the other edge over the intersection;
- otherwise, the average of the z coordinates of the points on the two edges over the intersection.

If no such intersection exists, `nil` is returned.

It is an error, and an exception will be thrown, if either `e1` or `e2` is not an edge.

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### length

`(length e)`

Return the length of the edge `e`.

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### minimaxd

`(minimaxd edge coord f)`

Apply function `f` to `coord` of the vertices at start and end of `edge` and return the result. Intended use case is `f` = `min` or `max`, `coord` is `:x`, `:y` or `:z`. No checks are made for sane arguments.

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### on2d?

`(on2d? e v)`

True if vertex `v` is on edge `e` when projected onto the x, y plane.

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### on?

`(on? e v)`

True if the vertex `v` is on the edge `e`.

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### overlaps2d?

`(overlaps2d? e1 e2)`

True if the recangle in the x,y plane bisected by edge `e1` overlaps that bisected by edge `e2`. It is an error if either `e1` or `e2` is not an edge.

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### parallel?

`(parallel? & edges)`

True if all `edges` passed are parallel with one another.

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### unit-vector

`(unit-vector e)`

Return an vertex parallel to `e` starting from the coordinate origin. Two edges which are parallel will have the same unit vector.

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