doodle/pkg/collision/bounding_rect.go

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package collision
import "git.kirsle.net/go/render"
// GetBoundingRect computes the full pairs of points for the bounding box of
// the actor.
//
// The X,Y coordinates are the position in the level of the actor,
// The W,H are the size of the actor's drawn box.
func GetBoundingRect(a Actor) render.Rect {
var (
P = a.Position()
S = a.Size()
)
return render.Rect{
X: P.X,
Y: P.Y,
W: S.W,
H: S.H,
}
}
// GetBoundingRectHitbox returns the bounding rect of the Actor taking into
// account their self-declared collision hitbox.
//
// The rect returned has the X,Y coordinate set to the actor's position, plus
// the X,Y of their hitbox, if any.
//
// The W,H of the rect is the W,H of their declared hitbox.
//
// If the actor has NOT declared its hitbox, this function returns exactly the
// same way as GetBoundingRect() does.
func GetBoundingRectHitbox(a Actor, hitbox render.Rect) render.Rect {
rect := GetBoundingRect(a)
if !hitbox.IsZero() {
rect.X += hitbox.X
rect.Y += hitbox.Y
rect.W = hitbox.W
rect.H = hitbox.H
}
return rect
}
// SizePlusHitbox adjusts an actor's canvas Size() to better fit the
// declared Hitbox by the actor's script.
func SizePlusHitbox(size render.Rect, hitbox render.Rect) render.Rect {
size.X += hitbox.X
size.Y += hitbox.Y
size.W -= size.W - hitbox.W
size.H -= size.H - hitbox.H
return size
}