ginger/gim/line.go

126 lines
2.8 KiB
Go
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package main
import (
"github.com/mediocregopher/ginger/gim/geo"
"github.com/mediocregopher/ginger/gim/terminal"
)
var lineSegments = func() map[[2]geo.XY]string {
m := map[[2]geo.XY]string{
{geo.Left, geo.Right}: "─",
{geo.Down, geo.Up}: "│",
{geo.Right, geo.Down}: "┌",
{geo.Left, geo.Down}: "┐",
{geo.Right, geo.Up}: "└",
{geo.Left, geo.Up}: "┘",
}
// the inverse segments use the same characters
for seg, str := range m {
seg[0], seg[1] = seg[1], seg[0]
m[seg] = str
}
return m
}()
var edgeSegments = map[geo.XY]string{
geo.Up: "┴",
geo.Down: "┬",
geo.Left: "┤",
geo.Right: "├",
}
// actual unicode arrows were fucking up my terminal, and they didn't even
// connect properly with the line segments anyway
var arrows = map[geo.XY]string{
geo.Up: "^",
geo.Down: "v",
geo.Left: "<",
geo.Right: ">",
}
type line [2]*box
// given the "primary" direction the line should be headed, picks a possible
// secondary one which may be used to detour along the path in order to reach
// the destination (in the case that the two boxes are diagonal from each other)
func (l line) secondaryDir(primary geo.XY) geo.XY {
fromRect, toRect := l[0].rect(), l[1].rect()
rels := make([]int, len(geo.Units))
for i, dir := range geo.Units {
rels[i] = toRect.Edge(dir.Inv()) - fromRect.Edge(dir)
if dir == geo.Up || dir == geo.Left {
rels[i] *= -1
}
}
var secondary geo.XY
var secondaryMax int
var secondarySet bool
for i, rel := range rels {
if geo.Units[i] == primary {
continue
} else if geo.Units[i][0] == 0 && primary[0] == 0 {
continue
} else if geo.Units[i][1] == 0 && primary[1] == 0 {
continue
} else if !secondarySet || rel > secondaryMax {
secondary = geo.Units[i]
secondaryMax = rel
secondarySet = true
}
}
return secondary
}
func (l line) draw(term *terminal.Terminal, dir geo.XY) {
from, to := *l[0], *l[1]
dirSec := l.secondaryDir(dir)
dirInv := dir.Inv()
start := from.rect().EdgeMidpoint(dir, rounder)
end := to.rect().EdgeMidpoint(dirInv, rounder)
mid := start.Midpoint(end, rounder)
along := func(xy, dir geo.XY) int {
if dir[0] != 0 {
return xy[0]
}
return xy[1]
}
var pts []geo.XY
midPrim := along(mid, dir)
endSec := along(end, dirSec)
for curr := start; curr != end; {
pts = append(pts, curr)
if prim := along(curr, dir); prim == midPrim {
if sec := along(curr, dirSec); sec != endSec {
curr = curr.Add(dirSec)
continue
}
}
curr = curr.Add(dir)
}
for i, pt := range pts {
var str string
switch {
case i == 0:
str = edgeSegments[dir]
case i == len(pts)-1:
str = arrows[dir]
default:
prev, next := pts[i-1], pts[i+1]
seg := [2]geo.XY{
prev.Sub(pt),
next.Sub(pt),
}
str = lineSegments[seg]
}
term.MoveCursorTo(pt)
term.Printf(str)
}
}