Noah Petherbridge
08e65c32b5
* 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.
137 lines
3.1 KiB
Go
137 lines
3.1 KiB
Go
package collision
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import (
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"errors"
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"math"
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"git.kirsle.net/go/render"
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)
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// Actor is a subset of the uix.Actor interface with just the methods needed
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// for collision checking purposes.
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type Actor interface {
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Position() render.Point
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Size() render.Rect
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Grounded() bool
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SetGrounded(bool)
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}
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// BoxCollision holds the result of a collision BetweenBoxes.
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type BoxCollision struct {
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// A and B are the indexes of the boxes sent to BetweenBoxes.
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A int
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B int
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// Overlap is the rect of how the boxes overlap.
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Overlap render.Rect
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}
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// IndexTuple holds two integers used as array indexes.
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type IndexTuple [2]int
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// BetweenBoxes checks if there is a collision between any
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// two bounding rectangles.
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//
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// This returns a generator that spits out indexes of the
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// intersecting boxes.
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func BetweenBoxes(boxes []render.Rect) chan BoxCollision {
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generator := make(chan BoxCollision)
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go func() {
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// Outer loop: test each box for intersection with the others.
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for i, box := range boxes {
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for j, other := range boxes {
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if i == j {
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continue
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}
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collision, err := CompareBoxes(box, other)
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if err == nil {
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collision.A = i
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collision.B = j
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generator <- collision
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}
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}
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}
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close(generator)
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}()
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return generator
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}
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// CompareBoxes checks if two boxes overlaps and returns information about
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// the overlap. The boxes are bounding rectangles like those given to
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// BetweenBoxes().
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func CompareBoxes(box, other render.Rect) (BoxCollision, error) {
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if box.Intersects(other) {
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var (
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overlap = OverlapRelative(box, other)
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topLeft = overlap.TopLeft()
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bottomRight = overlap.BottomRight()
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)
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return BoxCollision{
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Overlap: render.Rect{
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X: topLeft.X,
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Y: topLeft.Y,
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W: bottomRight.X,
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H: bottomRight.Y,
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},
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}, nil
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}
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return BoxCollision{}, errors.New("boxes do not intersect")
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}
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/*
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OverlapRelative returns the Overlap box using coordinates relative
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to the source rect instead of absolute coordinates.
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*/
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func OverlapRelative(source, other render.Rect) CollisionBox {
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var (
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// Move the source rect to 0,0 and record the distance we need
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// to go to get there, so we can move the other rect the same.
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deltaX = 0 - source.X
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deltaY = 0 - source.Y
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)
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source.X = 0
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source.Y = 0
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other.X += deltaX
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other.Y += deltaY
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return Overlap(source, other)
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}
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/*
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Overlap returns the overlap rectangle between two boxes.
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The two rects given have an X,Y coordinate and their W,H are their
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width and heights.
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The returned CollisionBox uses absolute coordinates in the same space
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as the passed-in rects.
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*/
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func Overlap(a, b render.Rect) CollisionBox {
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max := func(x, y int) int {
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return int(math.Max(float64(x), float64(y)))
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}
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min := func(x, y int) int {
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return int(math.Min(float64(x), float64(y)))
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}
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var (
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A = GetCollisionBox(a)
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B = GetCollisionBox(b)
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ATL = A.TopLeft()
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ABR = A.BottomRight()
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BTL = B.TopLeft()
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BBR = B.BottomRight()
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// Coordinates of the intersection box.
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X1, Y1 = max(ATL.X, BTL.X), max(ATL.Y, BTL.Y)
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X2, Y2 = min(ABR.X, BBR.X), min(ABR.Y, BBR.Y)
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)
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return NewBox(render.NewPoint(X1, Y1), render.NewPoint(X2, Y2))
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}
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