func makeBall(b ball) Ball {
img := canvas.Box(ballSize, ballSize, image.NewUniform(b.col), 1, image.Black)
p := b.p.point().Sub(image.Pt(ballSize/2, ballSize/2))
item := canvas.NewImage(img, true, p)
window.AddItem(item)
window.Raise(item, nil, false)
return Ball{item}
}
func clear() {
bbox := cvs.Bbox()
output = image.NewRGBA(bbox)
for i := 0; i < bbox.Dx(); i++ {
for j := 0; j < bbox.Dy(); j++ {
output.Set(i, j, color.RGBA{0, 0, 0, 0xff})
}
}
cvs.AddItem(canvas.NewImage(output, true, image.Point{X: 0, Y: 0}))
}
func paint() {
world.Lock()
cvs.AddItem(canvas.NewImage(output, true, image.Point{X: 0, Y: 0}))
cvs.Flush()
world.Unlock()
}
func makeRect(r image.Rectangle, col color.Color) {
img := canvas.Box(r.Dx(), r.Dy(), image.NewUniform(col), 1, image.Black)
item := canvas.NewImage(img, opaqueColor(col), r.Min)
window.AddItem(canvas.Draggable(item))
}