---
name: "SDLx::Controller::Interface"
section: "3pm"
platform: "linux"
package: "libsdl-perl"
version: "2.548-5+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/SDLx::Controller::Interface"
---

# SDLx::Controller::Interface(3pm)

Interface Physics and Rendering with the Controller with callbacks

## NAME

SDLx::Controller::Interface - Interface Physics and Rendering with the Controller with callbacks

## CATEGORY

Extension, Controller

## SYNOPSIS

```
 use SDL;
 use SDLx::App;
 use SDLx::Controller::Interface;
 #SDLx::App is a controller
 my $app = SDLx::App->new(width => 200, height => 200 );
 my $ball = SDLx::Controller::Interface->new( x=> 10, y => 50, v_x => 10, v_y=> 20 );
 #Set the initial state of the ball's physics, this is optional
 $ball->set_acceleration(
    sub {
              my ($time, $current_state) = @_;
              return( 0, -10, 0 ); # Return accelerations (x,y,rotation)
        }
 );
 my $ball_render = sub {
       my $state = shift;

       $app->draw_rect( undef, 0 );
       $app->draw_rect( [$state->x, $state->y, 10,10], [255,0,0,255] );
       $app->update();
 };
 $ball->attach( $app, $ball_render, @params );
 $app->run();
 $ball->detach(); #can be called at anytime (for example when ball 'dies')
```

## DESCRIPTION

## METHODS

### set\_acceleration

Allows you to set the acceleration callback for defining the interface's behaviour in terms of x,y and rotation.

```
  $interface->set_acceleration (
      sub {
         my ($time, $current_state) = @_;

         return ( $accel_x, $accel_y, $torque );
      }
  );
```

These accelerations are arbitrary and can be set to any frame of reference. Your render callback will handle how to interpret it.

The callback will receive the time and the current state as a `"SDLx::Controller::State"` element.

### attach

Attaches the interface to a controller with a render callback

```
  $interface->attach( $controller, $render, @params );
```

Where `$render` is a callback that receives the interpolated `"SDLx::Controller::State"`.

```
  my $render = sub {
        my ($state, @params) = @_;
        # draw the current $state.
  };
```

The `@params` are any extra parameters you would like to pass to the `$render` callback.

### current

```
  my $current_state = $interface->current();
```

Returns the current state of the interface as a `"SDLx::Controller::State"`.

### previous

```
  my $previous_state = $interface->previous();
```

Returns the previous state of the interface as a `"SDLx::Controller::State"`.

### detach

```
  $interface->detach();
```

If `$interface` has been `attach()`'ed to any controller it will be detached now.

## OTHER METHODS

Don't use these unless you really really want to.

### acceleration

Call the acceleration callback once.

### interpolate

Interpolate the current state

### evaluate

Evaluate the new current and previous state.

### update

Update the states by integrating with time.

## AUTHORS

See "AUTHORS" in SDL.