package djup

DELTA: f32 : 1.0 / 60.0

@(export = true)
sim_tick :: proc "c" (cur, next: ^Snapshot) {
	if cur == nil || next == nil {
		return
	}
	context = next.ctx^

	next.tick = cur.tick + 1
	copy(next.metadata, cur.metadata)

	player_input_system(cur, next)
	ball_movement_system(cur, next)
}

player_input_system :: proc(cur, next: ^Snapshot) {
	for &e, id in soa_zip(m = cur.metadata, input = cur.player_inputs, ball = cur.balls) {
		if e.m < {.Exists, .PlayerInput, .Ball} {
			continue
		}

		PLAYER_ACCELERATION :: 1500
		PLAYER_DRAG :: 2

		acc :=
			vec2_normal(e.input.direction) * PLAYER_ACCELERATION + e.ball.velocity * -PLAYER_DRAG
		e.ball.velocity += acc * DELTA
		next.player_inputs[id] = e.input
	}
}

ball_movement_system :: proc(cur, next: ^Snapshot) {
	for &e, id in soa_zip(m = cur.metadata, ball = cur.balls) {
		if e.m < {.Exists, .Ball} {
			continue
		}

		next.balls[id].position = e.ball.velocity * DELTA
		next.balls[id].velocity = e.ball.velocity
	}
}