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day10: some cleanup

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alexchao26
2020-08-03 20:04:23 -04:00
parent 40f4e54bc2
commit 936489e620
5 changed files with 50 additions and 135 deletions
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day10/part2/trig/trig.go
+29 -51
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@@ -1,62 +1,40 @@
package trig
import (
"math"
)
// TangentAndDistance docz
// startX will "always" be 13
// startY will "always" be 11
// 0 <= angleOffVery < 360
func TangentAndDistance(startX, startY, endX, endY int) (angleOffVert, distance float64) {
rise, run := float64(endX)-float64(startX), float64(endY)-float64(startY)
// fmt.Println(rise, run)
// edge cases for verticals
if run == 0 && rise < 0 {
return 0, -1 * rise // endXY is up
}
if run == 0 && rise > 0 {
return 180, rise // endXY is down
}
// handle left or right?
if rise == 0 && run < 0 {
return 270, -1 * run // left
}
if rise == 0 && run > 0 {
return 90, run // right
}
// not verticals
// calculate return distance
distance = rise*rise + run*run
distance = math.Sqrt(distance)
// calculate arctangent which will be in radians
// determine quadrent
if rise < 0 && run > 0 { // top right
angleOffVert = -1 * math.Atan(run/rise) * 180 / math.Pi
} else if rise > 0 && run > 0 { // bottom right
angleOffVert = 90 + math.Atan(rise/run)*180/math.Pi
} else if rise > 0 && run < 0 { // bottom left
angleOffVert = 180 + -1*math.Atan(run/rise)*180/math.Pi
} else if rise < 0 && run < 0 { // top left
angleOffVert = 270 + math.Atan(rise/run)*180/math.Pi
}
return angleOffVert, distance
}
import "math"
/*
AngleOffVertical takes in two 2D points, it calculates the angle
between the line between then and a vertical line. The angle
returned is to the right of the vertical, i.e. from the vertical
and through the (mathematical) first quadrant
between the line and a vertical line (straight up from origin)
NOTE: "up"/"top" and "down" are lexically flipped b/c of drawing a grid
where 0, 0 is the top left corner and higher numbers physically go DOWN
but lexically increase/go UP 🤦‍♂️
*/
func AngleOffVertical(startX, startY, endX, endY int) float64 {
rise := float64(endX) - float64(startX)
run := float64(endY) - float64(startY)
return 0
var angle float64
// basically a big if/elseif/else block
switch {
case run == 0 && rise < 0: // up
angle = 0
case run == 0 && rise > 0: // down
angle = 180
case rise == 0 && run < 0: // left
angle = 270
case rise == 0 && run > 0: // right
angle = 90
case rise < 0 && run > 0: // top right
angle = -1 * math.Atan(run/rise) * 180 / math.Pi
case rise > 0 && run > 0: // bottom right
angle = 90 + math.Atan(rise/run)*180/math.Pi
case rise > 0 && run < 0: // bottom left
angle = 180 + -1*math.Atan(run/rise)*180/math.Pi
case rise < 0 && run < 0: // top left
angle = 270 + math.Atan(rise/run)*180/math.Pi
}
return angle
}
// Distance calculates the distance between two sets of 2D coordinates via Pythagorean's theorem