include/SDL_haptic.h

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 2008 Edgar Simo

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/

/**
 *  \file SDL_haptic.h
 *  
 *  \brief The SDL Haptic subsystem allows you to control haptic (force feedback)
 *         devices.
 *  
 *  The basic usage is as follows:
 *   - Initialize the Subsystem (::SDL_INIT_HAPTIC).
 *   - Open a Haptic Device.
 *    - SDL_HapticOpen() to open from index.
 *    - SDL_HapticOpenFromJoystick() to open from an existing joystick.
 *   - Create an effect (::SDL_HapticEffect).
 *   - Upload the effect with SDL_HapticNewEffect().
 *   - Run the effect with SDL_HapticRunEffect().
 *   - (optional) Free the effect with SDL_HapticDestroyEffect().
 *   - Close the haptic device with SDL_HapticClose().
 *
 * \par Example:
 * \code
 * int test_haptic( SDL_Joystick * joystick ) {
 *    SDL_Haptic *haptic;
 *    SDL_HapticEffect effect;
 *    int effect_id;
 *
 *    // Open the device
 *    haptic = SDL_HapticOpenFromJoystick( joystick );
 *    if (haptic == NULL) return -1; // Most likely joystick isn't haptic
 *
 *    // See if it can do sine waves
 *    if ((SDL_HapticQuery(haptic) & SDL_HAPTIC_SINE)==0) {
 *       SDL_HapticClose(haptic); // No sine effect
 *       return -1;
 *    }
 *
 *    // Create the effect
 *    memset( &effect, 0, sizeof(SDL_HapticEffect) ); // 0 is safe default
 *    effect.type = SDL_HAPTIC_SINE;
 *    effect.periodic.direction.type = SDL_HAPTIC_POLAR; // Polar coordinates
 *    effect.periodic.direction.dir[0] = 18000; // Force comes from south
 *    effect.periodic.period = 1000; // 1000 ms
 *    effect.periodic.magnitude = 20000; // 20000/32767 strength
 *    effect.periodic.length = 5000; // 5 seconds long
 *    effect.periodic.attack_length = 1000; // Takes 1 second to get max strength
 *    effect.periodic.fade_length = 1000; // Takes 1 second to fade away
 *
 *    // Upload the effect
 *    effect_id = SDL_HapticNewEffect( haptic, &effect );
 *
 *    // Test the effect
 *    SDL_HapticRunEffect( haptic, effect_id, 1 );
 *    SDL_Delay( 5000); // Wait for the effect to finish
 *
 *    // We destroy the effect, although closing the device also does this
 *    SDL_HapticDestroyEffect( haptic, effect_id );
 *
 *    // Close the device
 *    SDL_HapticClose(haptic);
 *
 *    return 0; // Success
 * }
 * \endcode
 *
 * You can also find out more information on my blog:
 * http://bobbens.dyndns.org/journal/2010/sdl_haptic/
 *
 * \author Edgar Simo Serra
 */

#ifndef _SDL_haptic_h
#define _SDL_haptic_h

#include "SDL_stdinc.h"
#include "SDL_error.h"
#include "SDL_joystick.h"

#include "begin_code.h"
/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
/* *INDENT-OFF* */
extern "C" {
   /* *INDENT-ON* */                                                         
#endif /* __cplusplus */

/**
 *  \typedef SDL_Haptic
 *  
 *  \brief The haptic structure used to identify an SDL haptic.
 *  
 *  \sa SDL_HapticOpen
 *  \sa SDL_HapticOpenFromJoystick
 *  \sa SDL_HapticClose
 */
struct _SDL_Haptic;
typedef struct _SDL_Haptic SDL_Haptic;


/**
 *  \name Haptic features
 *  
 *  Different haptic features a device can have.
 */
/*@{*/

/**
 *  \name Haptic effects
 */
/*@{*/

/**
 *  \brief Constant effect supported.
 *
 *  Constant haptic effect.
 *  
 *  \sa SDL_HapticCondition
 */
#define SDL_HAPTIC_CONSTANT   (1<<0)

/**
 *  \brief Sine wave effect supported.
 *  
 *  Periodic haptic effect that simulates sine waves.
 *  
 *  \sa SDL_HapticPeriodic
 */
#define SDL_HAPTIC_SINE       (1<<1)

/**
 *  \brief Square wave effect supported.
 *  
 *  Periodic haptic effect that simulates square waves.
 * 
 *  \sa SDL_HapticPeriodic
 */
#define SDL_HAPTIC_SQUARE     (1<<2)

/**
 *  \brief Triangle wave effect supported.
 *  
 *  Periodic haptic effect that simulates triangular waves.
 *  
 *  \sa SDL_HapticPeriodic
 */
#define SDL_HAPTIC_TRIANGLE   (1<<3)

/**
 *  \brief Sawtoothup wave effect supported.
 *  
 *  Periodic haptic effect that simulates saw tooth up waves.
 *  
 *  \sa SDL_HapticPeriodic
 */
#define SDL_HAPTIC_SAWTOOTHUP (1<<4)

/**
 *  \brief Sawtoothdown wave effect supported.
 *  
 *  Periodic haptic effect that simulates saw tooth down waves.
 *  
 *  \sa SDL_HapticPeriodic
 */
#define SDL_HAPTIC_SAWTOOTHDOWN (1<<5)

/**
 *  \brief Ramp effect supported.
 *  
 *  Ramp haptic effect.
 *  
 *  \sa SDL_HapticRamp
 */
#define SDL_HAPTIC_RAMP       (1<<6)

/**
 *  \brief Spring effect supported - uses axes position.
 *  
 *  Condition haptic effect that simulates a spring.  Effect is based on the
 *  axes position.
 *
 *  \sa SDL_HapticCondition
 */
#define SDL_HAPTIC_SPRING     (1<<7)

/**
 *  \brief Damper effect supported - uses axes velocity.
 *  
 *  Condition haptic effect that simulates dampening.  Effect is based on the
 *  axes velocity.
 *  
 *  \sa SDL_HapticCondition
 */
#define SDL_HAPTIC_DAMPER     (1<<8)

/**
 *  \brief Inertia effect supported - uses axes acceleration.
 *  
 *  Condition haptic effect that simulates inertia.  Effect is based on the axes
 *  acceleration.
 *
 *  \sa SDL_HapticCondition
 */
#define SDL_HAPTIC_INERTIA    (1<<9)

/**
 *  \brief Friction effect supported - uses axes movement.
 *  
 *  Condition haptic effect that simulates friction.  Effect is based on the 
 *  axes movement.
 *  
 *  \sa SDL_HapticCondition
 */
#define SDL_HAPTIC_FRICTION   (1<<10)

/**
 *  \brief Custom effect is supported.
 *  
 *  User defined custom haptic effect.
 */
#define SDL_HAPTIC_CUSTOM     (1<<11)

/*@}*//*Haptic effects*/

/* These last few are features the device has, not effects */

/**
 *  \brief Device can set global gain.
 *  
 *  Device supports setting the global gain.
 *  
 *  \sa SDL_HapticSetGain
 */
#define SDL_HAPTIC_GAIN       (1<<12)

/**
 *  \brief Device can set autocenter.
 *  
 *  Device supports setting autocenter.
 *  
 *  \sa SDL_HapticSetAutocenter
 */
#define SDL_HAPTIC_AUTOCENTER (1<<13)

/**
 *  \brief Device can be queried for effect status.
 *  
 *  Device can be queried for effect status.
 *  
 *  \sa SDL_HapticGetEffectStatus
 */
#define SDL_HAPTIC_STATUS     (1<<14)

/**
 *  \brief Device can be paused.
 *  
 *  \sa SDL_HapticPause
 *  \sa SDL_HapticUnpause
 */
#define SDL_HAPTIC_PAUSE      (1<<15)


/**
 * \name Direction encodings
 */
/*@{*/

/**
 *  \brief Uses polar coordinates for the direction.
 *  
 *  \sa SDL_HapticDirection
 */
#define SDL_HAPTIC_POLAR      0

/**
 *  \brief Uses cartesian coordinates for the direction.
 *  
 *  \sa SDL_HapticDirection
 */
#define SDL_HAPTIC_CARTESIAN  1

/**
 *  \brief Uses spherical coordinates for the direction.
 *  
 *  \sa SDL_HapticDirection
 */
#define SDL_HAPTIC_SPHERICAL  2

/*@}*//*Direction encodings*/

/*@}*//*Haptic features*/

/*
 * Misc defines.
 */

/**
 * \brief Used to play a device an infinite number of times.
 *
 * \sa SDL_HapticRunEffect
 */
#define SDL_HAPTIC_INFINITY   4294967295U


/**
 *  \brief Structure that represents a haptic direction.
 *  
 *  Directions can be specified by:
 *   - ::SDL_HAPTIC_POLAR : Specified by polar coordinates.
 *   - ::SDL_HAPTIC_CARTESIAN : Specified by cartesian coordinates.
 *   - ::SDL_HAPTIC_SPHERICAL : Specified by spherical coordinates.
 *
 *  Cardinal directions of the haptic device are relative to the positioning
 *  of the device.  North is considered to be away from the user.
 *
 *  The following diagram represents the cardinal directions:
 *  \verbatim
                 .--.
                 |__| .-------.
                 |=.| |.-----.|
                 |--| ||     ||
                 |  | |'-----'|
                 |__|~')_____('
                   [ COMPUTER ]
    
    
                     North (0,-1)
                         ^
                         |
                         |
    (1,0)  West <----[ HAPTIC ]----> East (-1,0)
                         |
                         |
                         v
                      South (0,1)
    
    
                      [ USER ]
                        \|||/
                        (o o)
                  ---ooO-(_)-Ooo---
    \endverbatim
 *  
 *  If type is ::SDL_HAPTIC_POLAR, direction is encoded by hundredths of a 
 *  degree starting north and turning clockwise.  ::SDL_HAPTIC_POLAR only uses
 *  the first \c dir parameter.  The cardinal directions would be:
 *   - North: 0 (0 degrees)
 *   - East: 9000 (90 degrees)
 *   - South: 18000 (180 degrees)
 *   - West: 27000 (270 degrees)
 *  
 *  If type is ::SDL_HAPTIC_CARTESIAN, direction is encoded by three positions
 *  (X axis, Y axis and Z axis (with 3 axes)).  ::SDL_HAPTIC_CARTESIAN uses
 *  the first three \c dir parameters.  The cardinal directions would be:
 *   - North:  0,-1, 0
 *   - East:  -1, 0, 0
 *   - South:  0, 1, 0
 *   - West:   1, 0, 0
 *  
 *  The Z axis represents the height of the effect if supported, otherwise
 *  it's unused.  In cartesian encoding (1, 2) would be the same as (2, 4), you
 *  can use any multiple you want, only the direction matters.
 *  
 *  If type is ::SDL_HAPTIC_SPHERICAL, direction is encoded by two rotations.
 *  The first two \c dir parameters are used.  The \c dir parameters are as 
 *  follows (all values are in hundredths of degrees):
 *   - Degrees from (1, 0) rotated towards (0, 1).
 *   - Degrees towards (0, 0, 1) (device needs at least 3 axes).
 *
 *
 *  Example of force coming from the south with all encodings (force coming
 *  from the south means the user will have to pull the stick to counteract):
 *  \code
 *  SDL_HapticDirection direction;
 *  
 *  // Cartesian directions
 *  direction.type = SDL_HAPTIC_CARTESIAN; // Using cartesian direction encoding.
 *  direction.dir[0] = 0; // X position
 *  direction.dir[1] = 1; // Y position
 *  // Assuming the device has 2 axes, we don't need to specify third parameter.
 *  
 *  // Polar directions
 *  direction.type = SDL_HAPTIC_POLAR; // We'll be using polar direction encoding.
 *  direction.dir[0] = 18000; // Polar only uses first parameter
 *  
 *  // Spherical coordinates
 *  direction.type = SDL_HAPTIC_SPHERICAL; // Spherical encoding
 *  direction.dir[0] = 9000; // Since we only have two axes we don't need more parameters.
 *  \endcode
 *
 *  \sa SDL_HAPTIC_POLAR
 *  \sa SDL_HAPTIC_CARTESIAN
 *  \sa SDL_HAPTIC_SPHERICAL
 *  \sa SDL_HapticEffect
 *  \sa SDL_HapticNumAxes
 */
typedef struct SDL_HapticDirection
{
    Uint8 type;         /**< The type of encoding. */
    Sint32 dir[3];      /**< The encoded direction. */
} SDL_HapticDirection;


/**
 *  \brief A structure containing a template for a Constant effect.
 *  
 *  The struct is exclusive to the ::SDL_HAPTIC_CONSTANT effect.
 *  
 *  A constant effect applies a constant force in the specified direction
 *  to the joystick.
 *  
 *  \sa SDL_HAPTIC_CONSTANT
 *  \sa SDL_HapticEffect
 */
typedef struct SDL_HapticConstant
{
    /* Header */
    Uint16 type;            /**< ::SDL_HAPTIC_CONSTANT */
    SDL_HapticDirection direction;  /**< Direction of the effect. */

    /* Replay */
    Uint32 length;          /**< Duration of the effect. */
    Uint16 delay;           /**< Delay before starting the effect. */

    /* Trigger */
    Uint16 button;          /**< Button that triggers the effect. */
    Uint16 interval;        /**< How soon it can be triggered again after button. */

    /* Constant */
    Sint16 level;           /**< Strength of the constant effect. */

    /* Envelope */
    Uint16 attack_length;   /**< Duration of the attack. */
    Uint16 attack_level;    /**< Level at the start of the attack. */
    Uint16 fade_length;     /**< Duration of the fade. */
    Uint16 fade_level;      /**< Level at the end of the fade. */
} SDL_HapticConstant;

/**
 *  \brief A structure containing a template for a Periodic effect.
 *  
 *  The struct handles the following effects:
 *   - ::SDL_HAPTIC_SINE
 *   - ::SDL_HAPTIC_SQUARE
 *   - ::SDL_HAPTIC_TRIANGLE
 *   - ::SDL_HAPTIC_SAWTOOTHUP
 *   - ::SDL_HAPTIC_SAWTOOTHDOWN
 *  
 *  A periodic effect consists in a wave-shaped effect that repeats itself
 *  over time.  The type determines the shape of the wave and the parameters
 *  determine the dimensions of the wave.
 *  
 *  Phase is given by hundredth of a cyle meaning that giving the phase a value
 *  of 9000 will displace it 25% of it's period.  Here are sample values:
 *   -     0: No phase displacement.
 *   -  9000: Displaced 25% of it's period.
 *   - 18000: Displaced 50% of it's period.
 *   - 27000: Displaced 75% of it's period.
 *   - 36000: Displaced 100% of it's period, same as 0, but 0 is preffered.
 *
 *  Examples:
 *  \verbatim
    SDL_HAPTIC_SINE
      __      __      __      __
     /  \    /  \    /  \    /
    /    \__/    \__/    \__/
    
    SDL_HAPTIC_SQUARE
     __    __    __    __    __
    |  |  |  |  |  |  |  |  |  |
    |  |__|  |__|  |__|  |__|  |
    
    SDL_HAPTIC_TRIANGLE
      /\    /\    /\    /\    /\
     /  \  /  \  /  \  /  \  /
    /    \/    \/    \/    \/
    
    SDL_HAPTIC_SAWTOOTHUP
      /|  /|  /|  /|  /|  /|  /|
     / | / | / | / | / | / | / |
    /  |/  |/  |/  |/  |/  |/  |
    
    SDL_HAPTIC_SAWTOOTHDOWN
    \  |\  |\  |\  |\  |\  |\  |
     \ | \ | \ | \ | \ | \ | \ |
      \|  \|  \|  \|  \|  \|  \|
    \endverbatim
 *  
 *  \sa SDL_HAPTIC_SINE
 *  \sa SDL_HAPTIC_SQUARE
 *  \sa SDL_HAPTIC_TRIANGLE
 *  \sa SDL_HAPTIC_SAWTOOTHUP
 *  \sa SDL_HAPTIC_SAWTOOTHDOWN
 *  \sa SDL_HapticEffect
 */
typedef struct SDL_HapticPeriodic
{
    /* Header */
    Uint16 type;        /**< ::SDL_HAPTIC_SINE, ::SDL_HAPTIC_SQUARE,
                             ::SDL_HAPTIC_TRIANGLE, ::SDL_HAPTIC_SAWTOOTHUP or
                             ::SDL_HAPTIC_SAWTOOTHDOWN */
    SDL_HapticDirection direction;  /**< Direction of the effect. */

    /* Replay */
    Uint32 length;      /**< Duration of the effect. */
    Uint16 delay;       /**< Delay before starting the effect. */

    /* Trigger */
    Uint16 button;      /**< Button that triggers the effect. */
    Uint16 interval;    /**< How soon it can be triggered again after button. */

    /* Periodic */
    Uint16 period;      /**< Period of the wave. */
    Sint16 magnitude;   /**< Peak value. */
    Sint16 offset;      /**< Mean value of the wave. */
    Uint16 phase;       /**< Horizontal shift given by hundredth of a cycle. */

    /* Envelope */
    Uint16 attack_length;   /**< Duration of the attack. */
    Uint16 attack_level;    /**< Level at the start of the attack. */
    Uint16 fade_length; /**< Duration of the fade. */
    Uint16 fade_level;  /**< Level at the end of the fade. */
} SDL_HapticPeriodic;

/**
 *  \brief A structure containing a template for a Condition effect.
 *  
 *  The struct handles the following effects:
 *   - ::SDL_HAPTIC_SPRING: Effect based on axes position.
 *   - ::SDL_HAPTIC_DAMPER: Effect based on axes velocity.
 *   - ::SDL_HAPTIC_INERTIA: Effect based on axes acceleration.
 *   - ::SDL_HAPTIC_FRICTION: Effect based on axes movement.
 *  
 *  Direction is handled by condition internals instead of a direction member.
 *  The condition effect specific members have three parameters.  The first
 *  refers to the X axis, the second refers to the Y axis and the third
 *  refers to the Z axis.  The right terms refer to the positive side of the
 *  axis and the left terms refer to the negative side of the axis.  Please 
 *  refer to the ::SDL_HapticDirection diagram for which side is positive and
 *  which is negative.
 *  
 *  \sa SDL_HapticDirection
 *  \sa SDL_HAPTIC_SPRING
 *  \sa SDL_HAPTIC_DAMPER
 *  \sa SDL_HAPTIC_INERTIA
 *  \sa SDL_HAPTIC_FRICTION
 *  \sa SDL_HapticEffect
 */
typedef struct SDL_HapticCondition
{
    /* Header */
    Uint16 type;            /**< ::SDL_HAPTIC_SPRING, ::SDL_HAPTIC_DAMPER,
                                 ::SDL_HAPTIC_INERTIA or ::SDL_HAPTIC_FRICTION */
    SDL_HapticDirection direction;  /**< Direction of the effect - Not used ATM. */

    /* Replay */
    Uint32 length;          /**< Duration of the effect. */
    Uint16 delay;           /**< Delay before starting the effect. */

    /* Trigger */
    Uint16 button;          /**< Button that triggers the effect. */
    Uint16 interval;        /**< How soon it can be triggered again after button. */

    /* Condition */
    Uint16 right_sat[3];    /**< Level when joystick is to the positive side. */
    Uint16 left_sat[3];     /**< Level when joystick is to the negative side. */
    Sint16 right_coeff[3];  /**< How fast to increase the force towards the positive side. */
    Sint16 left_coeff[3];   /**< How fast to increase the force towards the negative side. */
    Uint16 deadband[3];     /**< Size of the dead zone. */
    Sint16 center[3];       /**< Position of the dead zone. */
} SDL_HapticCondition;

/**
 *  \brief A structure containing a template for a Ramp effect.
 *  
 *  This struct is exclusively for the ::SDL_HAPTIC_RAMP effect.
 *  
 *  The ramp effect starts at start strength and ends at end strength.
 *  It augments in linear fashion.  If you use attack and fade with a ramp
 *  they effects get added to the ramp effect making the effect become
 *  quadratic instead of linear.
 *  
 *  \sa SDL_HAPTIC_RAMP
 *  \sa SDL_HapticEffect
 */
typedef struct SDL_HapticRamp
{
    /* Header */
    Uint16 type;            /**< ::SDL_HAPTIC_RAMP */
    SDL_HapticDirection direction;  /**< Direction of the effect. */

    /* Replay */
    Uint32 length;          /**< Duration of the effect. */
    Uint16 delay;           /**< Delay before starting the effect. */

    /* Trigger */
    Uint16 button;          /**< Button that triggers the effect. */
    Uint16 interval;        /**< How soon it can be triggered again after button. */

    /* Ramp */
    Sint16 start;           /**< Beginning strength level. */
    Sint16 end;             /**< Ending strength level. */

    /* Envelope */
    Uint16 attack_length;   /**< Duration of the attack. */
    Uint16 attack_level;    /**< Level at the start of the attack. */
    Uint16 fade_length;     /**< Duration of the fade. */
    Uint16 fade_level;      /**< Level at the end of the fade. */
} SDL_HapticRamp;

/**
 *  \brief A structure containing a template for the ::SDL_HAPTIC_CUSTOM effect.
 *  
 *  A custom force feedback effect is much like a periodic effect, where the
 *  application can define it's exact shape.  You will have to allocate the
 *  data yourself.  Data should consist of channels * samples Uint16 samples.
 *  
 *  If channels is one, the effect is rotated using the defined direction.
 *  Otherwise it uses the samples in data for the different axes.
 *  
 *  \sa SDL_HAPTIC_CUSTOM
 *  \sa SDL_HapticEffect
 */
typedef struct SDL_HapticCustom
{
    /* Header */
    Uint16 type;            /**< ::SDL_HAPTIC_CUSTOM */
    SDL_HapticDirection direction;  /**< Direction of the effect. */

    /* Replay */
    Uint32 length;          /**< Duration of the effect. */
    Uint16 delay;           /**< Delay before starting the effect. */

    /* Trigger */
    Uint16 button;          /**< Button that triggers the effect. */
    Uint16 interval;        /**< How soon it can be triggered again after button. */

    /* Custom */
    Uint8 channels;         /**< Axes to use, minimum of one. */
    Uint16 period;          /**< Sample periods. */
    Uint16 samples;         /**< Amount of samples. */
    Uint16 *data;           /**< Should contain channels*samples items. */

    /* Envelope */
    Uint16 attack_length;   /**< Duration of the attack. */
    Uint16 attack_level;    /**< Level at the start of the attack. */
    Uint16 fade_length;     /**< Duration of the fade. */
    Uint16 fade_level;      /**< Level at the end of the fade. */
} SDL_HapticCustom;

/**
 *  \brief The generic template for any haptic effect.
 *  
 *  All values max at 32767 (0x7FFF).  Signed values also can be negative.
 *  Time values unless specified otherwise are in milliseconds.
 *  
 *  You can also pass ::SDL_HAPTIC_INFINITY to length instead of a 0-32767 
 *  value.  Neither delay, interval, attack_length nor fade_length support 
 *  ::SDL_HAPTIC_INFINITY.  Fade will also not be used since effect never ends.
 *  
 *  Additionally, the ::SDL_HAPTIC_RAMP effect does not support a duration of
 *  ::SDL_HAPTIC_INFINITY.
 *  
 *  Button triggers may not be supported on all devices, it is advised to not
 *  use them if possible.  Buttons start at index 1 instead of index 0 like
 *  they joystick.
 *  
 *  If both attack_length and fade_level are 0, the envelope is not used,
 *  otherwise both values are used.
 *  
 *  Common parts:
 *  \code
 *  // Replay - All effects have this
 *  Uint32 length;        // Duration of effect (ms).
 *  Uint16 delay;         // Delay before starting effect.
 *  
 *  // Trigger - All effects have this
 *  Uint16 button;        // Button that triggers effect.
 *  Uint16 interval;      // How soon before effect can be triggered again.
 *  
 *  // Envelope - All effects except condition effects have this
 *  Uint16 attack_length; // Duration of the attack (ms).
 *  Uint16 attack_level;  // Level at the start of the attack.
 *  Uint16 fade_length;   // Duration of the fade out (ms).
 *  Uint16 fade_level;    // Level at the end of the fade.
 *  \endcode
 *
 *
 *  Here we have an example of a constant effect evolution in time:
 *  \verbatim
    Strength
    ^
    |
    |    effect level -->  _________________
    |                     /                 \
    |                    /                   \
    |                   /                     \
    |                  /                       \ 
    | attack_level --> |                        \
    |                  |                        |  <---  fade_level
    |
    +--------------------------------------------------> Time
                       [--]                 [---]
                       attack_length        fade_length
    
    [------------------][-----------------------]
    delay               length
    \endverbatim
 *  
 *  Note either the attack_level or the fade_level may be above the actual
 *  effect level.
 *
 *  \sa SDL_HapticConstant
 *  \sa SDL_HapticPeriodic
 *  \sa SDL_HapticCondition
 *  \sa SDL_HapticRamp
 *  \sa SDL_HapticCustom
 */
typedef union SDL_HapticEffect
{
    /* Common for all force feedback effects */
    Uint16 type;                    /**< Effect type. */
    SDL_HapticConstant constant;    /**< Constant effect. */
    SDL_HapticPeriodic periodic;    /**< Periodic effect. */
    SDL_HapticCondition condition;  /**< Condition effect. */
    SDL_HapticRamp ramp;            /**< Ramp effect. */
    SDL_HapticCustom custom;        /**< Custom effect. */
} SDL_HapticEffect;


/* Function prototypes */
/**
 *  \brief Count the number of joysticks attached to the system.
 *  
 *  \return Number of haptic devices detected on the system.
 */
extern DECLSPEC int SDLCALL SDL_NumHaptics(void);

/**
 *  \brief Get the implementation dependent name of a Haptic device.
 *  
 *  This can be called before any joysticks are opened.
 *  If no name can be found, this function returns NULL.
 *  
 *  \param device_index Index of the device to get it's name.
 *  \return Name of the device or NULL on error.
 *
 *  \sa SDL_NumHaptics
 */
extern DECLSPEC const char *SDLCALL SDL_HapticName(int device_index);

/**
 *  \brief Opens a Haptic device for usage.
 *  
 *  The index passed as an argument refers to the N'th Haptic device on this 
 *  system.
 *
 *  When opening a haptic device, it's gain will be set to maximum and
 *  autocenter will be disabled.  To modify these values use
 *  SDL_HapticSetGain() and SDL_HapticSetAutocenter().
 *
 *  \param device_index Index of the device to open.
 *  \return Device identifier or NULL on error.
 *
 *  \sa SDL_HapticIndex
 *  \sa SDL_HapticOpenFromMouse
 *  \sa SDL_HapticOpenFromJoystick
 *  \sa SDL_HapticClose
 *  \sa SDL_HapticSetGain
 *  \sa SDL_HapticSetAutocenter
 *  \sa SDL_HapticPause
 *  \sa SDL_HapticStopAll
 */
extern DECLSPEC SDL_Haptic *SDLCALL SDL_HapticOpen(int device_index);

/**
 *  \brief Checks if the haptic device at index has been opened.
 *  
 *  \param device_index Index to check to see if it has been opened.
 *  \return 1 if it has been opened or 0 if it hasn't.
 *  
 *  \sa SDL_HapticOpen
 *  \sa SDL_HapticIndex
 */
extern DECLSPEC int SDLCALL SDL_HapticOpened(int device_index);

/**
 *  \brief Gets the index of a haptic device.
 *  
 *  \param haptic Haptic device to get the index of.
 *  \return The index of the haptic device or -1 on error.
 *  
 *  \sa SDL_HapticOpen
 *  \sa SDL_HapticOpened
 */
extern DECLSPEC int SDLCALL SDL_HapticIndex(SDL_Haptic * haptic);

/**
 *  \brief Gets whether or not the current mouse has haptic capabilities.
 *  
 *  \return SDL_TRUE if the mouse is haptic, SDL_FALSE if it isn't.
 *  
 *  \sa SDL_HapticOpenFromMouse
 */
extern DECLSPEC int SDLCALL SDL_MouseIsHaptic(void);

/**
 *  \brief Tries to open a haptic device from the current mouse.
 *  
 *  \return The haptic device identifier or NULL on error.
 *  
 *  \sa SDL_MouseIsHaptic
 *  \sa SDL_HapticOpen
 */
extern DECLSPEC SDL_Haptic *SDLCALL SDL_HapticOpenFromMouse(void);

/**
 *  \brief Checks to see if a joystick has haptic features.
 *  
 *  \param joystick Joystick to test for haptic capabilities.
 *  \return 1 if the joystick is haptic, 0 if it isn't
 *          or -1 if an error ocurred.
 *  
 *  \sa SDL_HapticOpenFromJoystick
 */
extern DECLSPEC int SDLCALL SDL_JoystickIsHaptic(SDL_Joystick * joystick);

/**
 *  \brief Opens a Haptic device for usage from a Joystick device.
 *  
 *  You must still close the haptic device seperately.  It will not be closed 
 *  with the joystick.
 *  
 *  When opening from a joystick you should first close the haptic device before
 *  closing the joystick device.  If not, on some implementations the haptic
 *  device will also get unallocated and you'll be unable to use force feedback
 *  on that device.
 *  
 *  \param joystick Joystick to create a haptic device from.
 *  \return A valid haptic device identifier on success or NULL on error.
 *  
 *  \sa SDL_HapticOpen
 *  \sa SDL_HapticClose
 */
extern DECLSPEC SDL_Haptic *SDLCALL SDL_HapticOpenFromJoystick(SDL_Joystick *
                                                               joystick);

/**
 *  \brief Closes a Haptic device previously opened with SDL_HapticOpen().
 *  
 *  \param haptic Haptic device to close.
 */
extern DECLSPEC void SDLCALL SDL_HapticClose(SDL_Haptic * haptic);

/**
 *  \brief Returns the number of effects a haptic device can store.
 *  
 *  On some platforms this isn't fully supported, and therefore is an
 *  aproximation.  Always check to see if your created effect was actually
 *  created and do not rely solely on SDL_HapticNumEffects().
 *  
 *  \param haptic The haptic device to query effect max.
 *  \return The number of effects the haptic device can store or
 *          -1 on error.
 *  
 *  \sa SDL_HapticNumEffectsPlaying
 *  \sa SDL_HapticQuery
 */
extern DECLSPEC int SDLCALL SDL_HapticNumEffects(SDL_Haptic * haptic);

/**
 *  \brief Returns the number of effects a haptic device can play at the same 
 *         time.
 *  
 *  This is not supported on all platforms, but will always return a value.  
 *  Added here for the sake of completness.
 *  
 *  \param haptic The haptic device to query maximum playing effects.
 *  \return The number of effects the haptic device can play at the same time
 *          or -1 on error.
 *
 *  \sa SDL_HapticNumEffects
 *  \sa SDL_HapticQuery
 */
extern DECLSPEC int SDLCALL SDL_HapticNumEffectsPlaying(SDL_Haptic * haptic);

/**
 *  \brief Gets the haptic devices supported features in bitwise matter.
 *  
 *  Example: 
 *  \code
 *  if (SDL_HapticQueryEffects(haptic) & SDL_HAPTIC_CONSTANT) {
 *      printf("We have constant haptic effect!");
 *  }
 *  \endcode
 *  
 *  \param haptic The haptic device to query.
 *  \return Haptic features in bitwise manner (OR'd).
 *  
 *  \sa SDL_HapticNumEffects
 *  \sa SDL_HapticEffectSupported
 */
extern DECLSPEC unsigned int SDLCALL SDL_HapticQuery(SDL_Haptic * haptic);


/**
 *  \brief Gets the number of haptic axes the device has.
 *  
 *  \sa SDL_HapticDirection
 */
extern DECLSPEC int SDLCALL SDL_HapticNumAxes(SDL_Haptic * haptic);

/**
 *  \brief Checks to see if effect is supported by haptic.
 *  
 *  \param haptic Haptic device to check on.
 *  \param effect Effect to check to see if it is supported.
 *  \return 1 if effect is supported, 0 if it isn't or -1 on error.
 *  
 *  \sa SDL_HapticQuery
 *  \sa SDL_HapticNewEffect
 */
extern DECLSPEC int SDLCALL SDL_HapticEffectSupported(SDL_Haptic * haptic,
                                                      SDL_HapticEffect *
                                                      effect);

/**
 *  \brief Creates a new haptic effect on the device.
 *  
 *  \param haptic Haptic device to create the effect on.
 *  \param effect Properties of the effect to create.
 *  \return The id of the effect on success or -1 on error.
 *  
 *  \sa SDL_HapticUpdateEffect
 *  \sa SDL_HapticRunEffect
 *  \sa SDL_HapticDestroyEffect
 */
extern DECLSPEC int SDLCALL SDL_HapticNewEffect(SDL_Haptic * haptic,
                                                SDL_HapticEffect * effect);

/**
 *  \brief Updates the properties of an effect.
 *  
 *  Can be used dynamically, although behaviour when dynamically changing
 *  direction may be strange.  Specifically the effect may reupload itself
 *  and start playing from the start.  You cannot change the type either when
 *  running SDL_HapticUpdateEffect().
 *  
 *  \param haptic Haptic device that has the effect.
 *  \param effect Effect to update.
 *  \param data New effect properties to use.
 *  \return The id of the effect on success or -1 on error.
 *  
 *  \sa SDL_HapticNewEffect
 *  \sa SDL_HapticRunEffect
 *  \sa SDL_HapticDestroyEffect
 */
extern DECLSPEC int SDLCALL SDL_HapticUpdateEffect(SDL_Haptic * haptic,
                                                   int effect,
                                                   SDL_HapticEffect * data);

/**
 *  \brief Runs the haptic effect on it's assosciated haptic device.
 *  
 *  If iterations are ::SDL_HAPTIC_INFINITY, it'll run the effect over and over
 *  repeating the envelope (attack and fade) every time.  If you only want the
 *  effect to last forever, set ::SDL_HAPTIC_INFINITY in the effect's length
 *  parameter.
 *  
 *  \param haptic Haptic device to run the effect on.
 *  \param effect Identifier of the haptic effect to run.
 *  \param iterations Number of iterations to run the effect. Use
 *         ::SDL_HAPTIC_INFINITY for infinity.
 *  \return 0 on success or -1 on error.
 *  
 *  \sa SDL_HapticStopEffect
 *  \sa SDL_HapticDestroyEffect
 *  \sa SDL_HapticGetEffectStatus
 */
extern DECLSPEC int SDLCALL SDL_HapticRunEffect(SDL_Haptic * haptic,
                                                int effect,
                                                Uint32 iterations);

/**
 *  \brief Stops the haptic effect on it's assosciated haptic device.
 *  
 *  \param haptic Haptic device to stop the effect on.
 *  \param effect Identifier of the effect to stop.
 *  \return 0 on success or -1 on error.
 *  
 *  \sa SDL_HapticRunEffect
 *  \sa SDL_HapticDestroyEffect
 */
extern DECLSPEC int SDLCALL SDL_HapticStopEffect(SDL_Haptic * haptic,
                                                 int effect);

/**
 *  \brief Destroys a haptic effect on the device.
 *  
 *  This will stop the effect if it's running.  Effects are automatically 
 *  destroyed when the device is closed.
 *  
 *  \param haptic Device to destroy the effect on.
 *  \param effect Identifier of the effect to destroy.
 *  
 *  \sa SDL_HapticNewEffect
 */
extern DECLSPEC void SDLCALL SDL_HapticDestroyEffect(SDL_Haptic * haptic,
                                                     int effect);

/**
 *  \brief Gets the status of the current effect on the haptic device.
 *  
 *  Device must support the ::SDL_HAPTIC_STATUS feature.
 *  
 *  \param haptic Haptic device to query the effect status on.
 *  \param effect Identifier of the effect to query it's status.
 *  \return 0 if it isn't playing, ::SDL_HAPTIC_PLAYING if it is playing
 *          or -1 on error.
 *  
 *  \sa SDL_HapticRunEffect
 *  \sa SDL_HapticStopEffect
 */
extern DECLSPEC int SDLCALL SDL_HapticGetEffectStatus(SDL_Haptic * haptic,
                                                      int effect);

/**
 *  \brief Sets the global gain of the device.
 *  
 *  Device must support the ::SDL_HAPTIC_GAIN feature.
 *  
 *  The user may specify the maxmimum gain by setting the environment variable
 *  ::SDL_HAPTIC_GAIN_MAX which should be between 0 and 100.  All calls to
 *  SDL_HapticSetGain() will scale linearly using ::SDL_HAPTIC_GAIN_MAX as the
 *  maximum.
 *  
 *  \param haptic Haptic device to set the gain on.
 *  \param gain Value to set the gain to, should be between 0 and 100.
 *  \return 0 on success or -1 on error.
 *  
 *  \sa SDL_HapticQuery
 */
extern DECLSPEC int SDLCALL SDL_HapticSetGain(SDL_Haptic * haptic, int gain);

/**
 *  \brief Sets the global autocenter of the device.
 *  
 *  Autocenter should be between 0 and 100.  Setting it to 0 will disable 
 *  autocentering.
 *
 *  Device must support the ::SDL_HAPTIC_AUTOCENTER feature.
 *
 *  \param haptic Haptic device to set autocentering on.
 *  \param autocenter Value to set autocenter to, 0 disables autocentering.
 *  \return 0 on success or -1 on error.
 *  
 *  \sa SDL_HapticQuery
 */
extern DECLSPEC int SDLCALL SDL_HapticSetAutocenter(SDL_Haptic * haptic,
                                                    int autocenter);

/**
 *  \brief Pauses a haptic device.
 *  
 *  Device must support the ::SDL_HAPTIC_PAUSE feature.  Call 
 *  SDL_HapticUnpause() to resume playback.
 *  
 *  Do not modify the effects nor add new ones while the device is paused.
 *  That can cause all sorts of weird errors.
 *  
 *  \param haptic Haptic device to pause.
 *  \return 0 on success or -1 on error.
 *  
 *  \sa SDL_HapticUnpause
 */
extern DECLSPEC int SDLCALL SDL_HapticPause(SDL_Haptic * haptic);

/**
 *  \brief Unpauses a haptic device.
 *  
 *  Call to unpause after SDL_HapticPause().
 *  
 *  \param haptic Haptic device to pause.
 *  \return 0 on success or -1 on error.
 *  
 *  \sa SDL_HapticPause
 */
extern DECLSPEC int SDLCALL SDL_HapticUnpause(SDL_Haptic * haptic);

/**
 *  \brief Stops all the currently playing effects on a haptic device.
 *  
 *  \param haptic Haptic device to stop.
 *  \return 0 on success or -1 on error.
 */
extern DECLSPEC int SDLCALL SDL_HapticStopAll(SDL_Haptic * haptic);


/* Ends C function definitions when using C++ */
#ifdef __cplusplus
/* *INDENT-OFF* */
}
/* *INDENT-ON* */
#endif
#include "close_code.h"

#endif /* _SDL_haptic_h */

/* vi: set ts=4 sw=4 expandtab: */