124 lines
3.1 KiB
Go
124 lines
3.1 KiB
Go
package game
|
|
|
|
import (
|
|
"encoding/gob"
|
|
"image"
|
|
"math"
|
|
|
|
"drjosh.dev/gurgle/engine"
|
|
"github.com/hajimehoshi/ebiten/v2"
|
|
"github.com/hajimehoshi/ebiten/v2/inpututil"
|
|
)
|
|
|
|
func init() {
|
|
gob.Register(Awakeman{})
|
|
}
|
|
|
|
type Awakeman struct {
|
|
engine.Sprite
|
|
|
|
CameraID string
|
|
|
|
camera *engine.Camera
|
|
vx, vy float64
|
|
facingLeft bool
|
|
coyoteTimer int
|
|
|
|
animIdleLeft, animIdleRight, animRunLeft, animRunRight *engine.Anim
|
|
}
|
|
|
|
func (aw *Awakeman) Update() error {
|
|
const (
|
|
ε = 0.2
|
|
restitution = -0.3
|
|
gravity = 0.3
|
|
airResistance = -0.01 // ⇒ terminal velocity = 30
|
|
jumpVelocity = -4.2
|
|
runVelocity = 1.4
|
|
coyoteTime = 5
|
|
)
|
|
|
|
// High-school physics time! Under constant acceleration:
|
|
// v = v_0 + a*t
|
|
// and
|
|
// s = t * (v_0 + v) / 2
|
|
// (note t is in ticks and s is in world units)
|
|
// and since we get one Update per tick (t = 1),
|
|
// v = v_0 + a,
|
|
// and
|
|
// s = (v_0 + v) / 2.
|
|
// Capture current v_0 to use later.
|
|
ux, uy := aw.vx, aw.vy
|
|
|
|
// Has traction?
|
|
if aw.CollidesAt(aw.Pos.Add(image.Pt(0, 1))) {
|
|
// Not falling.
|
|
// Instantly decelerate (AW absorbs all kinetic E in legs, or something)
|
|
aw.vy = 0
|
|
aw.coyoteTimer = coyoteTime
|
|
} else {
|
|
// Falling. v = v_0 + a, and a = gravity + airResistance(v_0)
|
|
aw.vy += gravity + airResistance*aw.vy
|
|
if aw.coyoteTimer > 0 {
|
|
aw.coyoteTimer--
|
|
}
|
|
}
|
|
|
|
// Handle controls
|
|
|
|
// NB: spacebar sometimes does things on web pages (scrolls down)
|
|
if aw.coyoteTimer > 0 && (inpututil.IsKeyJustPressed(ebiten.KeySpace) || inpututil.IsKeyJustPressed(ebiten.KeyZ)) {
|
|
// Jump. One frame of a = jumpVelocity (ignoring any gravity already applied this tick).
|
|
aw.vy = jumpVelocity
|
|
}
|
|
switch {
|
|
case ebiten.IsKeyPressed(ebiten.KeyLeft) || ebiten.IsKeyPressed(ebiten.KeyA):
|
|
aw.vx = -runVelocity
|
|
aw.SetAnim(aw.animRunLeft)
|
|
aw.facingLeft = true
|
|
case ebiten.IsKeyPressed(ebiten.KeyRight) || ebiten.IsKeyPressed(ebiten.KeyD):
|
|
aw.vx = runVelocity
|
|
aw.SetAnim(aw.animRunRight)
|
|
aw.facingLeft = false
|
|
default:
|
|
aw.vx = 0
|
|
aw.SetAnim(aw.animIdleRight)
|
|
if aw.facingLeft {
|
|
aw.SetAnim(aw.animIdleLeft)
|
|
}
|
|
}
|
|
aw.camera.Zoom = 1
|
|
if ebiten.IsKeyPressed(ebiten.KeyShift) {
|
|
aw.camera.Zoom = 2
|
|
}
|
|
/*
|
|
if inpututil.IsKeyJustPressed(ebiten.KeyR) {
|
|
aw.camera.Rotation += math.Pi / 6
|
|
}
|
|
*/
|
|
|
|
// s = (v_0 + v) / 2.
|
|
aw.MoveX((ux+aw.vx)/2, nil)
|
|
// For Y, on collision, bounce a little bit.
|
|
// Does not apply to X because controls override it anyway.
|
|
aw.MoveY((uy+aw.vy)/2, func() {
|
|
aw.vy *= restitution
|
|
if math.Abs(aw.vy) < ε {
|
|
aw.vy = 0
|
|
}
|
|
})
|
|
// aw.Pos is top-left corner, so add half size to get centre
|
|
aw.camera.Centre = aw.Pos.Add(aw.Size.Div(2))
|
|
return aw.Sprite.Update()
|
|
}
|
|
|
|
func (aw *Awakeman) Prepare(game *engine.Game) {
|
|
aw.camera = game.Component(aw.CameraID).(*engine.Camera)
|
|
|
|
aw.animIdleLeft = &engine.Anim{Def: engine.AnimDefs["aw_idle_left"]}
|
|
aw.animIdleRight = &engine.Anim{Def: engine.AnimDefs["aw_idle_right"]}
|
|
aw.animRunLeft = &engine.Anim{Def: engine.AnimDefs["aw_run_left"]}
|
|
aw.animRunRight = &engine.Anim{Def: engine.AnimDefs["aw_run_right"]}
|
|
}
|
|
|
|
func (aw *Awakeman) Scan() []interface{} { return []interface{}{&aw.Sprite} }
|