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|
module main
import gg
import gx
const rate = f32(1) / 60 * 10
struct App {
mut:
gg &gg.Context
anim &Anim
}
struct Anim {
mut:
time f32
reverse bool
}
fn (mut anim Anim) advance() {
if anim.reverse {
anim.time -= 1 * rate
} else {
anim.time += 1 * rate
}
// Use some arbitrary value that fits 60 fps
if anim.time > 80 * rate || anim.time < -80 * rate {
anim.reverse = !anim.reverse
}
}
fn main() {
mut app := &App{
gg: 0
anim: &Anim{}
}
app.gg = gg.new_context(
bg_color: gx.rgb(174, 198, 255)
width: 600
height: 400
window_title: 'Animated cubic Bézier curve'
frame_fn: frame
user_data: app
)
app.gg.run()
}
fn frame(mut app App) {
time := app.anim.time
p1_x := f32(200.0)
p1_y := f32(200.0) + (10 * time)
p2_x := f32(400.0)
p2_y := f32(200.0) + (10 * time)
ctrl_p1_x := f32(200.0) + (40 * time)
ctrl_p1_y := f32(100.0)
ctrl_p2_x := f32(400.0) + (-40 * time)
ctrl_p2_y := f32(100.0)
points := [p1_x, p1_y, ctrl_p1_x, ctrl_p1_y, ctrl_p2_x, ctrl_p2_y, p2_x, p2_y]
app.gg.begin()
app.gg.draw_cubic_bezier(points, gx.blue)
app.gg.end()
app.anim.advance()
}
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