Ilia Denisov
95 lines
1.7 KiB
Go
95 lines
1.7 KiB
Go
package util
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import (
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"galaxy/calc"
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"math"
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)
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// WrapF maps value into the half-open interval [0, float64(size)).
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// It supports negative input values and is used for torus coordinates
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// when the coordinate is represented as float64.
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//
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// size must be greater than zero.
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func WrapF(value float64, size int) float64 {
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if size <= 0 {
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panic("WrapF: size must be > 0")
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}
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s := float64(size)
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r := math.Mod(value, s)
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if r < 0 {
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r += s
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}
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// Protect against a possible boundary artifact and keep result in [0, s).
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// In normal cases math.Mod already gives a value with |r| < s.
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if r >= s {
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r -= s
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}
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return r
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}
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func NextTravelCoord(w, h uint32, x1, y1, x2, y2, delta float64) (float64, float64, bool) {
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deltaX, deltaY := calc.Deltas(w, h, x1, y1, x2, y2)
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distance := math.Hypot(deltaX, deltaY)
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if distance <= delta {
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return x2, y2, true
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}
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// [ ] refactor - remove extra vars
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xa := 0.
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ya := 0.
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xb := deltaX
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yb := deltaY
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d := distance
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d2 := delta
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xc := xa - (d2*(xa-xb))/d
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yc := ya - (d2*(ya-yb))/d
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// ---
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var tx, ty float64
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if math.Abs(x2-x1) > float64(w/2) {
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// moving across X boundary
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if x2 < x1 {
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// moving across higher border
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tx = math.Mod(x1+xc, float64(w))
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} else {
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// moving across lower border
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tx = x1 - xc
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if tx < 0 {
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tx = float64(w) + tx
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}
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}
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} else {
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if x2 < x1 {
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tx = x1 - xc
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} else {
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tx = x1 + xc
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}
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}
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if math.Abs(y2-y1) > float64(h/2) {
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// moving across Y boundary
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if y2 < y1 {
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// moving across higher border
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ty = math.Mod(y1+yc, float64(h))
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} else {
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// moving across lower border
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ty = y1 - yc
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if ty < 0 {
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ty = float64(h) + ty
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}
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}
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} else {
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if y2 < y1 {
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ty = y1 - yc
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} else {
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ty = y1 + yc
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}
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}
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return tx, ty, false
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}
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