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good enough for now

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This commit is contained in:
Josh Deprez 2021-09-08 17:43:15 +10:00
parent a1abd8ac3c
commit 5c313e8518
1 changed files with 1 additions and 9 deletions
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10
engine/misc.go
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@ -116,7 +116,7 @@ func polygonRectOverlap(polygon []image.Point, rect image.Rectangle) bool {
// Walk each edge of polygon.
for i, p := range polygon {
q := polygon[(i+1)%len(polygon)]
// Exclude edges that don't overlap the rectangle in any way.
// Pretend the edge is a rectangle. Exclude those that don't overlap.
if !rect.Overlaps(image.Rectangle{p, q}.Canon()) {
continue
}
@ -130,17 +130,13 @@ func polygonRectOverlap(polygon []image.Point, rect image.Rectangle) bool {
min := (rect.Min.Y - p.Y) * d.X
max := (rect.Max.Y - p.Y) * d.X
// Test left side of rect
//if (rect.Min.X >= p.X || rect.Min.X >= q.X) && (rect.Min.X <= p.X || rect.Min.X <= q.X) {
if t := (rect.Min.X - p.X) * d.Y; min <= t && t < max {
return true
}
//}
// Test right side of rect
//if (rect.Max.X > p.X || rect.Max.X > q.X) && (rect.Max.X <= p.X || rect.Max.X <= q.X) {
if t := (rmax.X - p.X) * d.Y; min <= t && t < max {
return true
}
//}
}
// If the polygon edge is not horizontal, test the top and bottom sides
if d.Y != 0 {
@ -150,18 +146,14 @@ func polygonRectOverlap(polygon []image.Point, rect image.Rectangle) bool {
min := (rect.Min.X - p.X) * d.Y
max := (rect.Max.X - p.X) * d.Y
// Test top side of rect
//if (rect.Min.Y >= p.Y || rect.Min.Y >= q.Y) && (rect.Min.Y <= p.Y || rect.Min.Y <= q.Y) {
if t := (rect.Min.Y - p.Y) * d.X; min <= t && t < max {
return true
}
//}
// Test bottom side of rect
//if (rect.Max.Y > p.Y || rect.Max.Y > q.Y) && (rect.Max.Y <= p.Y || rect.Max.Y <= q.Y) {
if t := (rmax.Y - p.Y) * d.X; min <= t && t < max {
return true
}
//}
}
}
return false