Difference between revisions of "Conversion between love objects and FFI structures"
m (some fixes, inlined code, edited so it keeps to its own namespace, fixed function formatting.) |
(Meant no malice with my last commit, accidentally left in the minor edit flag. This'll be a major edit to compensate.) |
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This page details how to convert between löve objects and [http://luajit.org/ext_ffi.html FFI] (Foreign Function Interface) structures. | This page details how to convert between löve objects and [http://luajit.org/ext_ffi.html FFI] (Foreign Function Interface) structures. | ||
| − | Love objects in lua are always stored in a userdata object (Proxy) that contains the object itself, and a type identifier. | + | Love objects in lua are always stored in a userdata object (Proxy) that contains the object itself, and a type identifier. See the code below for details. |
| − | |||
| − | == | + | == Function == |
This function converts a love object into a FFI cdata object. It returns the object itself (not the Proxy object), it's type and type name. | This function converts a love object into a FFI cdata object. It returns the object itself (not the Proxy object), it's type and type name. | ||
=== Synopsis === | === Synopsis === | ||
| Line 13: | Line 12: | ||
</source> | </source> | ||
=== Arguments === | === Arguments === | ||
| − | {{param|Object|Object| | + | {{param|Object|Object|A LÖVE object.}} |
=== Returns === | === Returns === | ||
{{param|cdata|Pointer|An FFI pointer containing the object's location.}} | {{param|cdata|Pointer|An FFI pointer containing the object's location.}} | ||
| Line 19: | Line 18: | ||
{{param|number|TypeEnum|The LÖVE object's type as an enumeration value.}} | {{param|number|TypeEnum|The LÖVE object's type as an enumeration value.}} | ||
| + | == Function == | ||
This function converts a FFI cdata object into a Proxy userdata object, it is required to give the type name to assign the metatable to the userdata object, and the type id for the Proxy object. | This function converts a FFI cdata object into a Proxy userdata object, it is required to give the type name to assign the metatable to the userdata object, and the type id for the Proxy object. | ||
| Line 30: | Line 30: | ||
{{param|number|TypeEnum|The LÖVE object's type as an enumeration value.}} | {{param|number|TypeEnum|The LÖVE object's type as an enumeration value.}} | ||
=== Returns === | === Returns === | ||
| − | {{param|Object|Object| | + | {{param|Object|Object|A LÖVE object.}} |
== Code == | == Code == | ||
Revision as of 18:05, 1 November 2016
|
This is NOT recommended for anyone to use. It will break at any time. The only non-breaking conversion between love objects and FFI data is via Data:getPointer, which you can cast to a FFI pointer via ffi.cast. The garbage collector may erase the original userdata at any time. |
This page details how to convert between löve objects and FFI (Foreign Function Interface) structures.
Love objects in lua are always stored in a userdata object (Proxy) that contains the object itself, and a type identifier. See the code below for details.
Contents
Function
This function converts a love object into a FFI cdata object. It returns the object itself (not the Proxy object), it's type and type name.
Synopsis
Pointer, Type, TypeEnum = objectToPointer( Object )
Arguments
Object Object- A LÖVE object.
Returns
cdata Pointer- An FFI pointer containing the object's location.
string Type- The LÖVE object's type.
number TypeEnum- The LÖVE object's type as an enumeration value.
Function
This function converts a FFI cdata object into a Proxy userdata object, it is required to give the type name to assign the metatable to the userdata object, and the type id for the Proxy object.
Synopsis
Object = pointerToObject( Pointer, Type, TypeEnum )
Arguments
cdata Pointer- An FFI pointer containing the object's location.
string Type- The LÖVE object's type.
number TypeEnum- The LÖVE object's type as an enumeration value.
Returns
Object Object- A LÖVE object.
Code
<source lang="lua"> ffi = require("ffi")
ffi.cdef [[
typedef enum {
INVALID_ID = 0,
OBJECT_ID,
DATA_ID,
MODULE_ID,
STREAM_ID,
// Filesystem.
FILESYSTEM_FILE_ID,
FILESYSTEM_DROPPED_FILE_ID,
FILESYSTEM_FILE_DATA_ID,
// Font
FONT_GLYPH_DATA_ID,
FONT_RASTERIZER_ID,
// Graphics
GRAPHICS_DRAWABLE_ID,
GRAPHICS_TEXTURE_ID,
GRAPHICS_IMAGE_ID,
GRAPHICS_QUAD_ID,
GRAPHICS_FONT_ID,
GRAPHICS_PARTICLE_SYSTEM_ID,
GRAPHICS_SPRITE_BATCH_ID,
GRAPHICS_CANVAS_ID,
GRAPHICS_SHADER_ID,
GRAPHICS_MESH_ID,
GRAPHICS_TEXT_ID,
GRAPHICS_VIDEO_ID,
// Image
IMAGE_IMAGE_DATA_ID,
IMAGE_COMPRESSED_IMAGE_DATA_ID,
// Joystick
JOYSTICK_JOYSTICK_ID,
// Math
MATH_RANDOM_GENERATOR_ID,
MATH_BEZIER_CURVE_ID,
MATH_COMPRESSED_DATA_ID,
// Audio
AUDIO_SOURCE_ID,
// Sound
SOUND_SOUND_DATA_ID,
SOUND_DECODER_ID,
// Mouse
MOUSE_CURSOR_ID,
// Physics
PHYSICS_WORLD_ID,
PHYSICS_CONTACT_ID,
PHYSICS_BODY_ID,
PHYSICS_FIXTURE_ID,
PHYSICS_SHAPE_ID,
PHYSICS_CIRCLE_SHAPE_ID,
PHYSICS_POLYGON_SHAPE_ID,
PHYSICS_EDGE_SHAPE_ID,
PHYSICS_CHAIN_SHAPE_ID,
PHYSICS_JOINT_ID,
PHYSICS_MOUSE_JOINT_ID,
PHYSICS_DISTANCE_JOINT_ID,
PHYSICS_PRISMATIC_JOINT_ID,
PHYSICS_REVOLUTE_JOINT_ID,
PHYSICS_PULLEY_JOINT_ID,
PHYSICS_GEAR_JOINT_ID,
PHYSICS_FRICTION_JOINT_ID,
PHYSICS_WELD_JOINT_ID,
PHYSICS_ROPE_JOINT_ID,
PHYSICS_WHEEL_JOINT_ID,
PHYSICS_MOTOR_JOINT_ID,
// Thread
THREAD_THREAD_ID,
THREAD_CHANNEL_ID,
// Video
VIDEO_VIDEO_STREAM_ID,
// The modules themselves. Only add abstracted modules here.
MODULE_FILESYSTEM_ID,
MODULE_GRAPHICS_ID,
MODULE_IMAGE_ID,
MODULE_SOUND_ID,
// Count the number of bits needed.
TYPE_MAX_ENUM
} Type;
typedef struct Object {
} Object;
typedef struct Proxy {
Type type;
Object * object;
};
]]
local conv = {}
function conv.objectToPointer(Object)
local Proxy = ffi.cast("Proxy *", Object)
return Proxy.object, tonumber(Proxy.type), Object:type()
end
function conv.pointerToObject(CData, Type, TypeName)
local Object = newproxy(true)
local Metatable = debug.getregistry()[TypeName]
debug.setmetatable(Object, Metatable)
local Proxy = ffi.cast("Proxy *", Object)
Proxy.type = Type
Proxy.object = CData
return Object
end
return conv
