private Vec2 transform(Vec2 p, Size size)
{
return(V.xy(
size.Width / 2f + p.x,
size.Height * 2f / 3f - p.y
));
}
private void Calculate()
{
var frame_next = frame + 1;
if (frame_next >= frames)
{
return;
}
for (var shape = 0; shape < shapes; shape++)
{
var radius_curr = radius_arr[shape];
var pos_curr = pos_arr[shape, frame];
var vel_curr = vel_arr[shape, frame];
var vel_next = vel_curr + dt * gravity;
var pos_next = pos_curr + (vel_next + vel_curr) * dt * 0.5f;
var t = wall_normal * (pos_next - wall_point);
if (t < radius_curr && vel_curr * wall_normal < 0f)
{
pos_next = mirror(wall_point + radius_curr * wall_normal, wall_normal, pos_next);
vel_next = mirror(V.zero(), wall_normal, vel_next) * restitution;
}
pos_arr[shape, frame_next] = pos_next;
vel_arr[shape, frame_next] = vel_next;
}
}
private V mirror(V mirror_point, V mirror_normal, V point)
{
var t = mirror_normal * (point - mirror_point);
return(point - 2 * t * mirror_normal);
}