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Implement jump buffering

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This commit is contained in:
Josh Deprez 2021-08-20 13:09:26 +10:00
parent e98b730465
commit 9a3da85999
1 changed files with 34 additions and 13 deletions
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47
game/aw.go
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@ -23,6 +23,7 @@ type Awakeman struct {
vx, vy float64 vx, vy float64
facingLeft bool facingLeft bool
coyoteTimer int coyoteTimer int
jumpBuffer int
noclip bool noclip bool
animIdleLeft, animIdleRight, animRunLeft, animRunRight *engine.Anim animIdleLeft, animIdleRight, animRunLeft, animRunRight *engine.Anim
@ -40,10 +41,13 @@ func (aw *Awakeman) Update() error {
if err := upd(); err != nil { if err := upd(); err != nil {
return err return err
} }
// Update the camera
aw.camera.Zoom = 1 aw.camera.Zoom = 1
if ebiten.IsKeyPressed(ebiten.KeyShift) { if ebiten.IsKeyPressed(ebiten.KeyShift) {
aw.camera.Zoom = 2 aw.camera.Zoom = 2
} }
// aw.Pos is top-left corner, so add half size to get centre
aw.camera.Centre = aw.Pos.Add(aw.Size.Div(2)) aw.camera.Centre = aw.Pos.Add(aw.Size.Div(2))
return nil return nil
} }
@ -66,13 +70,14 @@ func (aw *Awakeman) noclipUpdate() error {
func (aw *Awakeman) realUpdate() error { func (aw *Awakeman) realUpdate() error {
const ( const (
ε = 0.2 ε = 0.2
restitution = -0.3 restitution = -0.3
gravity = 0.3 gravity = 0.3
airResistance = -0.01 // ⇒ terminal velocity = 30 airResistance = -0.01 // ⇒ terminal velocity = 30
jumpVelocity = -4.2 jumpVelocity = -4.2
runVelocity = 1.4 runVelocity = 1.4
coyoteTime = 5 coyoteTime = 5
jumpBufferTime = 5
) )
// High-school physics time! Under constant acceleration: // High-school physics time! Under constant acceleration:
@ -91,23 +96,40 @@ func (aw *Awakeman) realUpdate() error {
if aw.CollidesAt(aw.Pos.Add(image.Pt(0, 1))) { if aw.CollidesAt(aw.Pos.Add(image.Pt(0, 1))) {
// Not falling. // Not falling.
// Instantly decelerate (AW absorbs all kinetic E in legs, or something) // Instantly decelerate (AW absorbs all kinetic E in legs, or something)
aw.vy = 0 if aw.jumpBuffer > 0 {
aw.coyoteTimer = coyoteTime // Tried to jump recently -- so jump
aw.vy = jumpVelocity
aw.jumpBuffer = 0
} else {
// Can jump now or soon.
aw.vy = 0
aw.coyoteTimer = coyoteTime
}
} else { } else {
// Falling. v = v_0 + a, and a = gravity + airResistance(v_0) // Falling. v = v_0 + a, and a = gravity + airResistance(v_0)
aw.vy += gravity + airResistance*aw.vy aw.vy += gravity + airResistance*aw.vy
if aw.coyoteTimer > 0 { if aw.coyoteTimer > 0 {
aw.coyoteTimer-- aw.coyoteTimer--
} }
if aw.jumpBuffer > 0 {
aw.jumpBuffer--
}
} }
// Handle controls // Handle controls
// NB: spacebar sometimes does things on web pages (scrolls down) // NB: spacebar sometimes does things on web pages (scrolls down)
if aw.coyoteTimer > 0 && (inpututil.IsKeyJustPressed(ebiten.KeySpace) || inpututil.IsKeyJustPressed(ebiten.KeyZ)) { if inpututil.IsKeyJustPressed(ebiten.KeySpace) || inpututil.IsKeyJustPressed(ebiten.KeyZ) {
// Jump. One frame of a = jumpVelocity (ignoring any gravity already applied this tick). // On ground or recently on ground?
aw.vy = jumpVelocity if aw.coyoteTimer > 0 {
// Jump. One frame of a = jumpVelocity (ignoring any gravity already applied this tick).
aw.vy += jumpVelocity
} else {
// Buffer the jump in case aw hits the ground soon.
aw.jumpBuffer = jumpBufferTime
}
} }
// Left and right
switch { switch {
case ebiten.IsKeyPressed(ebiten.KeyLeft) || ebiten.IsKeyPressed(ebiten.KeyA): case ebiten.IsKeyPressed(ebiten.KeyLeft) || ebiten.IsKeyPressed(ebiten.KeyA):
aw.vx = -runVelocity aw.vx = -runVelocity
@ -135,7 +157,6 @@ func (aw *Awakeman) realUpdate() error {
aw.vy = 0 aw.vy = 0
} }
}) })
// aw.Pos is top-left corner, so add half size to get centre
return aw.Sprite.Update() return aw.Sprite.Update()
} }