108 lines
2.4 KiB
Go
108 lines
2.4 KiB
Go
package geom
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import "image"
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// Box describes an axis-aligned rectangular prism.
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type Box struct {
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Min, Max Int3
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}
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// String returns a string representation of b like "(3,4,5)-(6,5,8)".
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func (b Box) String() string {
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return b.Min.String() + "-" + b.Max.String()
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}
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// Empty reports whether the box contains no points.
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func (b Box) Empty() bool {
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return b.Min.X >= b.Max.X || b.Min.Y >= b.Max.Y || b.Min.Z >= b.Max.Z
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}
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// Eq reports whether b and c contain the same set of points. All empty boxes
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// are considered equal.
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func (b Box) Eq(c Box) bool {
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return b == c || b.Empty() && c.Empty()
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}
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// Overlaps reports whether b and c have non-empty intersection.
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func (b Box) Overlaps(c Box) bool {
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return !b.Empty() && !c.Empty() &&
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b.Min.X < c.Max.X && c.Min.X < b.Max.X &&
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b.Min.Y < c.Max.Y && c.Min.Y < b.Max.Y &&
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b.Min.Z < c.Max.Z && c.Min.Z < b.Max.Z
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}
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// Size returns b's width, height, and depth.
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func (b Box) Size() Int3 {
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return b.Max.Sub(b.Min)
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}
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// Centre returns the centre point of the box.
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func (b Box) Centre() Int3 {
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return b.Min.Add(b.Max).Div(2)
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}
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// Add offsets the box by vector p.
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func (b Box) Add(p Int3) Box {
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return Box{
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Min: b.Min.Add(p),
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Max: b.Max.Add(p),
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}
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}
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// Sub offsets the box by (-p).
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func (b Box) Sub(p Int3) Box {
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return Box{
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Min: b.Min.Sub(p),
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Max: b.Max.Sub(p),
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}
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}
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// Canon returns a copy of b that is well-formed.
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func (b Box) Canon() Box {
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if b.Max.X < b.Min.X {
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b.Min.X, b.Max.X = b.Max.X, b.Min.X
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}
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if b.Max.Y < b.Min.Y {
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b.Min.Y, b.Max.Y = b.Max.Y, b.Min.Y
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}
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if b.Max.Z < b.Min.Z {
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b.Min.Z, b.Max.Z = b.Max.Z, b.Min.Z
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}
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return b
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}
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// Back returns an image.Rectangle representing the back of the box, using
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// the given projection π.
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func (b Box) Back(π IntProjection) image.Rectangle {
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b.Max.Z = b.Min.Z
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return image.Rectangle{
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Min: π.Project(b.Min),
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Max: π.Project(b.Max),
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}
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}
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// Front returns an image.Rectangle representing the front of the box, using
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// the given projection π.
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func (b Box) Front(π IntProjection) image.Rectangle {
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b.Min.Z = b.Max.Z
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return image.Rectangle{
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Min: π.Project(b.Min),
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Max: π.Project(b.Max),
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}
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}
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// XY returns the image.Rectangle representing the box if we forgot about Z.
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func (b Box) XY() image.Rectangle {
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return image.Rectangle{
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Min: b.Min.XY(),
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Max: b.Max.XY(),
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}
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}
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// XZ returns the image.Rectangle representing the box if we forgot about Y.
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func (b Box) XZ() image.Rectangle {
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return image.Rectangle{
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Min: b.Min.XZ(),
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Max: b.Max.XZ(),
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}
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}
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