Noah Petherbridge
d14eaf7df2
* The F4 key to draw collision boxes works reliably again: it draws the player's hitbox in world-space using the canvas.DrawStrokes() function, rather than in screen-space so it follows the player reliably. * The F4 key also draws hitboxes for ALL other actors in the level: buttons, enemies, doors, etc. * The level geometry collision function is updated to respect a doodad's declared Hitbox from their script, which may result in a smaller box than their raw Canvas size. The result is tighter collision between doodads, and Boy's sprite is rather narrow for its square Canvas so collision on rightward geometry is tighter for the player character. * Collision checks between actors also respect the actor's declared hitboxes now, allowing for Boy to get even closer to a locked door before being blocked.
138 lines
3.1 KiB
Go
138 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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Hitbox() render.Rect
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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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