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bunch of probably irrelevant fenceposting

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This commit is contained in:
Josh Deprez 2021-09-08 17:37:10 +10:00
parent 1af3e141fb
commit a1abd8ac3c
1 changed files with 26 additions and 21 deletions
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47
engine/misc.go
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@ -92,20 +92,20 @@ func polygonRectOverlap(polygon []image.Point, rect image.Rectangle) bool {
} }
} }
// Reduce Max to the inclusive bound. // Reduced Max (to the inclusive bound).
rect.Max = rect.Max.Sub(image.Pt(1, 1)) rmax := rect.Max.Sub(image.Pt(1, 1))
// Check if any vertex of the rect is inside the polygon. // Check if any vertex of the rect is inside the polygon.
if polygonContains(polygon, rect.Min) { if polygonContains(polygon, rect.Min) {
return true return true
} }
if polygonContains(polygon, rect.Max) { if polygonContains(polygon, rmax) {
return true return true
} }
if polygonContains(polygon, image.Pt(rect.Min.X, rect.Max.Y)) { if polygonContains(polygon, image.Pt(rect.Min.X, rmax.Y)) {
return true return true
} }
if polygonContains(polygon, image.Pt(rect.Max.X, rect.Min.Y)) { if polygonContains(polygon, image.Pt(rmax.X, rect.Min.Y)) {
return true return true
} }
@ -116,6 +116,11 @@ func polygonRectOverlap(polygon []image.Point, rect image.Rectangle) bool {
// Walk each edge of polygon. // Walk each edge of polygon.
for i, p := range polygon { for i, p := range polygon {
q := polygon[(i+1)%len(polygon)] q := polygon[(i+1)%len(polygon)]
// Exclude edges that don't overlap the rectangle in any way.
if !rect.Overlaps(image.Rectangle{p, q}.Canon()) {
continue
}
d := q.Sub(p) d := q.Sub(p)
// If the polygon edge is not vertical, test left and right sides // If the polygon edge is not vertical, test left and right sides
if d.X != 0 { if d.X != 0 {
@ -125,17 +130,17 @@ func polygonRectOverlap(polygon []image.Point, rect image.Rectangle) bool {
min := (rect.Min.Y - p.Y) * d.X min := (rect.Min.Y - p.Y) * d.X
max := (rect.Max.Y - p.Y) * d.X max := (rect.Max.Y - p.Y) * d.X
// Test left side of rect // 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 (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 { if t := (rect.Min.X - p.X) * d.Y; min <= t && t < max {
return true return true
}
} }
//}
// Test right side of rect // 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 (rect.Max.X > p.X || rect.Max.X > q.X) && (rect.Max.X <= p.X || rect.Max.X <= q.X) {
if t := (rect.Max.X - p.X) * d.Y; min <= t && t <= max { if t := (rmax.X - p.X) * d.Y; min <= t && t < max {
return true return true
}
} }
//}
} }
// If the polygon edge is not horizontal, test the top and bottom sides // If the polygon edge is not horizontal, test the top and bottom sides
if d.Y != 0 { if d.Y != 0 {
@ -145,18 +150,18 @@ func polygonRectOverlap(polygon []image.Point, rect image.Rectangle) bool {
min := (rect.Min.X - p.X) * d.Y min := (rect.Min.X - p.X) * d.Y
max := (rect.Max.X - p.X) * d.Y max := (rect.Max.X - p.X) * d.Y
// Test top side of rect // 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 (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 { if t := (rect.Min.Y - p.Y) * d.X; min <= t && t < max {
return true return true
}
} }
//}
// Test bottom side of rect // 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 (rect.Max.Y > p.Y || rect.Max.Y > q.Y) && (rect.Max.Y <= p.Y || rect.Max.Y <= q.Y) {
if t := (rect.Max.Y - p.Y) * d.X; min <= t && t <= max { if t := (rmax.Y - p.Y) * d.X; min <= t && t < max {
return true return true
}
} }
//}
} }
} }
return false return false