doodle/pkg/collision/bounding_rect.go
Noah Petherbridge 08e65c32b5 Overhaul the Platformer Physics System
* Player character now experiences acceleration and friction when
  walking around the map!
* Actor position and movement had to be converted from int's
  (render.Point) to float64's to support fine-grained acceleration
  steps.
* Added "physics" package and physics.Vector to be a float64 counterpart
  for render.Point. Vector is used for uix.Actor.Position() for the sake
  of movement math. Vector is flattened back to a render.Point for
  collision purposes, since the levels and hitboxes are pixel-bound.
* Refactor the uix.Actor to no longer extend the doodads.Drawing (so it
  can have a Position that's a Vector instead of a Point). This broke
  some code that expected `.Doodad` to directly reference the
  Drawing.Doodad: now you had to refer to it as `a.Drawing.Doodad` which
  was ugly. Added convenience method .Doodad() for a shortcut.
* Moved functions like GetBoundingRect() from doodads package to
  collision, where it uses its own slimmer Actor interface for just the
  relevant methods it needs.
2020-04-04 21:00:32 -07:00

43 lines
1.0 KiB
Go

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
}