Sdk script api documentation

Built-in scripting functions.

Namespace: dmScript
Include: #include <dmsdk/script/script.h>
TYPES
HContext The script context
ENUMS
LuaBufferOwnership buffer ownership
STRUCTS
struct dmScript::LuaHBuffer Lua wrapper for a dmBuffer::HBuffer
struct dmScript::LuaCallbackInfo callback info struct
FUNCTIONS
dmGameObject::HInstance CheckGOInstance(lua_State* L) Get current game object instance Works in both gam...
lua_State* CheckGOInstance(lua_State* L, int index) Get gameobject instance The instance reference (u...
boolean dmScript::IsBuffer(lua_State* L, int index) check if the value is a dmScript::LuaHBuffer
void dmScript::PushBuffer(lua_State* L, dmScript::LuaHBuffer buffer) push a LuaHBuffer onto the supplied lua state
LuaHBuffer* dmScript::CheckBuffer(lua_State* L, int index) retrieve a HBuffer from the supplied lua state
LuaHBuffer* dmScript::CheckBufferNoError(lua_State* L, int index) retrieve a HBuffer from the supplied lua state.
int dmScript::Ref(lua_State* L, int table) wrapper for luaL_ref.
void dmScript::Unref(lua_State* L, int table, int reference) wrapper for luaL_unref.
void dmScript::GetInstance(lua_State* L) Retrieve current script instance from the global t...
void dmScript::SetInstance(lua_State* L) Sets the current script instance Set the value on ...
bool dmScript::IsInstanceValid(lua_State* L) Check if the script instance in the lua state is v...
lua_State* dmScript::GetMainThread(lua_State* L) Retrieve the main thread lua state from any lua st...
dmVMath::Vector3* dmScript::ToVector3(lua_State* L, int index) get the value at index as a dmVMath::Vector3*
 dmScript::IsVector3( L,  index) Check if the value at #index is a dmVMath::Vector3...
void dmScript::PushVector3(lua_State* L, dmVMath::Vector3 v) push a dmVMath::Vector3 onto the Lua stack
dmVMath::Vector3* dmScript::CheckVector3(lua_State* L, int index) check if the value is a dmVMath::Vector3
dmVMath::Vector4* dmScript::ToVector4(lua_State* L, int index) get the value at index as a dmVMath::Vector4*
 dmScript::IsVector4( L,  index) Check if the value at #index is a dmVMath::Vector4...
void dmScript::PushVector4(lua_State* L, dmVMath::Vector4 v) push a dmVMath::Vector4 on the stack
dmVMath::Vector4* dmScript::CheckVector4(lua_State* L, int index) check if the value is a dmVMath::Vector3
dmVMath::Quat* dmScript::ToQuat(lua_State* L, int index) get the value at index as a dmVMath::Quat*
 dmScript::IsQuat( L,  index) Check if the value at #index is a dmVMath::Quat*
void dmScript::PushQuat(lua_State* L, dmVMath::Quat quat) push a dmVMath::Quat onto the Lua stack
dmVMath::Quat* dmScript::CheckQuat(lua_State* L, int index) check if the value is a dmVMath::Vector3
dmVMath::Matrix4* dmScript::ToMatrix4(lua_State* L, int index) get the value at index as a dmVMath::Matrix4*
 dmScript::IsMatrix4( L,  index) Check if the value at #index is a dmVMath::Matrix4...
void dmScript::PushMatrix4(lua_State* L, dmVMath::Matrix4 matrix) push a dmVMath::Matrix4 onto the Lua stack
dmVMath::Matrix4* dmScript::CheckMatrix4(lua_State* L, int index) check if the value is a dmVMath::Matrix4
 dmScript::IsHash(lua_State* L, int index) Check if the value at #index is a hash
void dmScript::PushHash(lua_State* L,  hash) Push a hash value onto the supplied lua state, wil...
 dmScript::CheckHash(lua_State* L, int index) get hash value
 dmScript::CheckHashOrString(lua_State* L, int index) get hash from hash or string
const char* GetStringFromHashOrString(lua_State* L, int index, char* buffer, uint32_t buffer_length) Gets as good as possible printable string from a h...
int dmJson::Type(lua_State* L, dmJson::Document doc, int index, char* error_str_out, size_t error_str_size) convert a dmJson::Document to a Lua table
 dmScript::CreateCallback( L,  index) Register a Lua callback.
void dmScript::IsCallbackValid( cbk) Check if Lua callback is valid.
void dmScript::DestroyCallback( cbk) Deletes the Lua callback
 dmScript::GetCallbackLuaContext( cbk) Gets the Lua context from a callback struct
 dmScript::SetupCallback( cbk) Setups up the Lua callback prior to a call to dmScript::PCall()
void dmScript::TeardownCallback( cbk) Cleans up the stack after SetupCallback+PCall calls
 dmScript::PCall( L,  nargs,  nresult) This function wraps lua_pcall with the addition of...
int RefInInstance(lua_State* L) Creates a reference to the value at top of stack, ...
void UnrefInInstance(lua_State* L, int ref) Deletes the instance local lua reference Expects ...
dmMessage::Result RefInInstance(lua_State* L, const char* url, dmMessage::URL* out_url, dmMessage::URL* default_url) Resolves a url in string format into a dmMessage::...
const char* UrlToString(dmMessage::URL* url, char* buffer, uint32_t buffer_size) Converts a URL into a readable string. Useful for ...
MACROS
DM_LUA_STACK_CHECK(L, diff) helper macro to validate the Lua stack state before leaving a function.
DM_LUA_ERROR(fmt, args) helper macro to validate the Lua stack state and throw a lua error.

Functions

CheckGOInstance

dmGameObject::HInstance CheckGOInstance(lua_State* L)

Get current game object instance Works in both gameobjects and gui scripts

PARAMETERS

lua_State* L lua state

RETURNS

dmGameObject::HInstance

CheckGOInstance

lua_State* CheckGOInstance(lua_State* L, int index)

Get gameobject instance The instance reference (url) at stack index "index" will be resolved to an instance.

PARAMETERS

lua_State* L lua state
int index lua-arg

RETURNS

lua_State* gameobject instance

EXAMPLES

How to get the position of a gameobject in a script extension 
static int get_position(lua_State* L)
{
    DM_LUA_STACK_CHECK(L, 3);
    dmGameObject::HInstance instance = dmScript::CheckGOInstance(L, 1);
    dmVMath::Point3 position = dmGameObject::GetPosition(instance);
    lua_pushnumber(L, position.getX());
    lua_pushnumber(L, position.getY());
    lua_pushnumber(L, position.getZ());
    return 3;
}

dmScript::IsBuffer

boolean dmScript::IsBuffer(lua_State* L, int index)

Check if the value is a dmScript::LuaHBuffer

PARAMETERS

lua_State* L lua state
int index Index of the value

RETURNS

boolean True if value at index is a LuaHBuffer

dmScript::PushBuffer

void dmScript::PushBuffer(lua_State* L, dmScript::LuaHBuffer buffer)

Will increase the stack by 1.

PARAMETERS

lua_State* L lua state
dmScript::LuaHBuffer buffer buffer to push

EXAMPLES

How to push a buffer and give Lua ownership of the buffer (GC) 
dmScript::LuaHBuffer luabuf(buffer, dmScript::OWNER_LUA);
PushBuffer(L, luabuf);
How to push a buffer and keep ownership in C++ 
dmScript::LuaHBuffer luabuf(buffer, dmScript::OWNER_C);
PushBuffer(L, luabuf);

dmScript::CheckBuffer

LuaHBuffer* dmScript::CheckBuffer(lua_State* L, int index)

Check if the value in the supplied index on the lua stack is a HBuffer and returns it.

PARAMETERS

lua_State* L lua state
int index Index of the value

RETURNS

LuaHBuffer* pointer to dmScript::LuaHBuffer

dmScript::CheckBufferNoError

LuaHBuffer* dmScript::CheckBufferNoError(lua_State* L, int index)

Retrieve a HBuffer from the supplied lua state. Check if the value in the supplied index on the lua stack is a HBuffer and returns it.

PARAMETERS

lua_State* L lua state
int index Index of the value

RETURNS

LuaHBuffer* pointer to dmScript::LuaHBuffer

dmScript::Ref

int dmScript::Ref(lua_State* L, int table)

Creates and returns a reference, in the table at index t, for the object at the top of the stack (and pops the object). It also tracks number of global references kept.

PARAMETERS

lua_State* L lua state
int table table the lua table that stores the references. E.g LUA_REGISTRYINDEX

RETURNS

int the new reference

dmScript::Unref

void dmScript::Unref(lua_State* L, int table, int reference)

Releases reference ref from the table at index t (see luaL_ref). The entry is removed from the table, so that the referred object can be collected. It also decreases the number of global references kept

PARAMETERS

lua_State* L lua state
int table table the lua table that stores the references. E.g LUA_REGISTRYINDEX
int reference the reference to the object

dmScript::GetInstance

void dmScript::GetInstance(lua_State* L)

Retrieve current script instance from the global table and place it on the top of the stack, only valid when set. (see dmScript::GetMainThread)

PARAMETERS

lua_State* L lua state

dmScript::SetInstance

void dmScript::SetInstance(lua_State* L)

Sets the current script instance Set the value on the top of the stack as the instance into the global table and pops it from the stack. (see dmScript::GetMainThread)

PARAMETERS

lua_State* L lua state

dmScript::IsInstanceValid

bool dmScript::IsInstanceValid(lua_State* L)

Check if the script instance in the lua state is valid. The instance is assumed to have been previously set by dmScript::SetInstance.

PARAMETERS

lua_State* L lua state

RETURNS

bool Returns true if the instance is valid

dmScript::GetMainThread

lua_State* dmScript::GetMainThread(lua_State* L)

Retrieve the main thread lua state from any lua state (main thread or coroutine).

PARAMETERS

lua_State* L lua state

RETURNS

lua_State* the main thread lua state

EXAMPLES

How to create a Lua callback 
dmScript::LuaCallbackInfo* g_MyCallbackInfo = 0;

static void InvokeCallback(dmScript::LuaCallbackInfo* cbk)
{
    if (!dmScript::IsCallbackValid(cbk))
        return;

    lua_State* L = dmScript::GetCallbackLuaContext(cbk);
    DM_LUA_STACK_CHECK(L, 0)

    if (!dmScript::SetupCallback(cbk))
    {
        dmLogError("Failed to setup callback");
        return;
    }

    lua_pushstring(L, "Hello from extension!");
    lua_pushnumber(L, 76);

    dmScript::PCall(L, 3, 0); // instance + 2

    dmScript::TeardownCallback(cbk);
}

static int Start(lua_State* L)
{
    DM_LUA_STACK_CHECK(L, 0);

    g_MyCallbackInfo = dmScript::CreateCallback(L, 1);

    return 0;
}

static int Update(lua_State* L)
{
    DM_LUA_STACK_CHECK(L, 0);

    static int count = 0;
    if( count++ == 5 )
    {
        InvokeCallback(g_MyCallbackInfo);
        if (g_MyCallbackInfo)
            dmScript::DestroyCallback(g_MyCallbackInfo);
        g_MyCallbackInfo = 0;
    }
    return 0;
}

dmScript::ToVector3

dmVMath::Vector3* dmScript::ToVector3(lua_State* L, int index)

Get the value at index as a dmVMath::Vector3*

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

dmVMath::Vector3* The pointer to the value, or 0 if not correct type

dmScript::IsVector3

 dmScript::IsVector3( L,  index)

Check if the value at #index is a dmVMath::Vector3*

PARAMETERS

L Lua state
index Index of the value

RETURNS

if value at #index is a dmVMath::Vector3*

dmScript::PushVector3

void dmScript::PushVector3(lua_State* L, dmVMath::Vector3 v)

Push a dmVMath::Vector3 value onto the supplied lua state, will increase the stack by 1.

PARAMETERS

lua_State* L Lua state
dmVMath::Vector3 v Vector3 value to push

dmScript::CheckVector3

dmVMath::Vector3* dmScript::CheckVector3(lua_State* L, int index)

Check if the value in the supplied index on the lua stack is a dmVMath::Vector3.

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

dmVMath::Vector3* The pointer to the value

dmScript::ToVector4

dmVMath::Vector4* dmScript::ToVector4(lua_State* L, int index)

Get the value at index as a dmVMath::Vector4*

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

dmVMath::Vector4* The pointer to the value, or 0 if not correct type

dmScript::IsVector4

 dmScript::IsVector4( L,  index)

Check if the value at #index is a dmVMath::Vector4*

PARAMETERS

L Lua state
index Index of the value

RETURNS

if value at #index is a dmVMath::Vector4*

dmScript::PushVector4

void dmScript::PushVector4(lua_State* L, dmVMath::Vector4 v)

Push a dmVMath::Vector4 value onto the supplied lua state, will increase the stack by 1.

PARAMETERS

lua_State* L Lua state
dmVMath::Vector4 v dmVMath::Vector4 value to push

dmScript::CheckVector4

dmVMath::Vector4* dmScript::CheckVector4(lua_State* L, int index)

Check if the value in the supplied index on the lua stack is a dmVMath::Vector3.

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

dmVMath::Vector4* The pointer to the value

dmScript::ToQuat

dmVMath::Quat* dmScript::ToQuat(lua_State* L, int index)

Get the value at index as a dmVMath::Quat*

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

dmVMath::Quat* The pointer to the value, or 0 if not correct type

dmScript::IsQuat

 dmScript::IsQuat( L,  index)

Check if the value at #index is a dmVMath::Quat*

PARAMETERS

L Lua state
index Index of the value

RETURNS

if value at #index is a dmVMath::Quat*

dmScript::PushQuat

void dmScript::PushQuat(lua_State* L, dmVMath::Quat quat)

Push a quaternion value onto Lua stack. Will increase the stack by 1.

PARAMETERS

lua_State* L Lua state
dmVMath::Quat quat dmVMath::Quat value to push

dmScript::CheckQuat

dmVMath::Quat* dmScript::CheckQuat(lua_State* L, int index)

Check if the value in the supplied index on the lua stack is a dmVMath::Quat.

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

dmVMath::Quat* The pointer to the value

dmScript::ToMatrix4

dmVMath::Matrix4* dmScript::ToMatrix4(lua_State* L, int index)

Get the value at index as a dmVMath::Matrix4*

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

dmVMath::Matrix4* The pointer to the value, or 0 if not correct type

dmScript::IsMatrix4

 dmScript::IsMatrix4( L,  index)

Check if the value at #index is a dmVMath::Matrix4*

PARAMETERS

L Lua state
index Index of the value

RETURNS

if value at #index is a dmVMath::Matrix4*

dmScript::PushMatrix4

void dmScript::PushMatrix4(lua_State* L, dmVMath::Matrix4 matrix)

Push a matrix4 value onto the Lua stack. Will increase the stack by 1.

PARAMETERS

lua_State* L Lua state
dmVMath::Matrix4 matrix dmVMath::Matrix4 value to push

dmScript::CheckMatrix4

dmVMath::Matrix4* dmScript::CheckMatrix4(lua_State* L, int index)

Check if the value in the supplied index on the lua stack is a dmVMath::Matrix4.

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

dmVMath::Matrix4* The pointer to the value

dmScript::IsHash

 dmScript::IsHash(lua_State* L, int index)

Check if the value at #index is a hash

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

if the value at #index is a hash

dmScript::PushHash

void dmScript::PushHash(lua_State* L,  hash)

Push a hash value onto the supplied lua state, will increase the stack by 1.

PARAMETERS

lua_State* L Lua state
hash dmhash_t Hash value to push

dmScript::CheckHash

 dmScript::CheckHash(lua_State* L, int index)

Check if the value in the supplied index on the lua stack is a hash.

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

hash value

dmScript::CheckHashOrString

 dmScript::CheckHashOrString(lua_State* L, int index)

Check if the value in the supplied index on the lua stack is a hash or string. If it is a string, it gets hashed on the fly

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

hash value

GetStringFromHashOrString

const char* GetStringFromHashOrString(lua_State* L, int index, char* buffer, uint32_t buffer_length)

Gets as good as possible printable string from a hash or string

PARAMETERS

lua_State* L Lua state
int index Index of the value
char* buffer buffer receiving the value
uint32_t buffer_length the buffer length

RETURNS

const char* Returns buffer. If buffer is non null, it will always contain a null terminated string. "" if the hash could not be looked up.

dmJson::Type

int dmJson::Type(lua_State* L, dmJson::Document doc, int index, char* error_str_out, size_t error_str_size)

Convert a dmJson::Document document to Lua table.

PARAMETERS

lua_State* L lua state
dmJson::Document doc JSON document
int index index of JSON node
char* error_str_out if an error is encountered, the error string is written to this argument
size_t error_str_size size of error_str_out

RETURNS

int <0 if it fails. >=0 if it succeeds.

dmScript::CreateCallback

 dmScript::CreateCallback( L,  index)

Stores the current Lua state plus references to the script instance (self) and the callback. Expects SetInstance() to have been called prior to using this method. The allocated data is created on the Lua stack and references are made against the instances own context table. If the callback is not explicitly deleted with DestroyCallback() the references and data will stay around until the script instance is deleted.

PARAMETERS

L Lua state
index Lua stack index of the function

RETURNS

callback struct if successful, 0 otherwise

EXAMPLES

static int SomeFunction(lua_State* L) // called from Lua
{
    LuaCallbackInfo* cbk = dmScript::CreateCallback(L, 1);
    ... store the callback for later
}

static void InvokeCallback(LuaCallbackInfo* cbk)
{
    lua_State* L = dmScript::GetCallbackLuaContext(cbk);
    DM_LUA_STACK_CHECK(L, 0);

    if (!dmScript::SetupCallback(callback))
    {
        return;
    }

    lua_pushstring(L, "hello");

    dmScript::PCall(L, 2, 0); // self + # user arguments

    dmScript::TeardownCallback(callback);
    dmScript::DestroyCallback(cbk); // only do this if you're not using the callback again
}

dmScript::IsCallbackValid

void dmScript::IsCallbackValid( cbk)

Check if Lua callback is valid.

PARAMETERS

cbk Lua callback struct

dmScript::DestroyCallback

void dmScript::DestroyCallback( cbk)

Deletes the Lua callback

PARAMETERS

cbk Lua callback struct

dmScript::GetCallbackLuaContext

 dmScript::GetCallbackLuaContext( cbk)

Gets the Lua context from a callback struct

PARAMETERS

cbk Lua callback struct

RETURNS

Lua state

dmScript::SetupCallback

 dmScript::SetupCallback( cbk)

The Lua stack after a successful call: 

   [-4] old instance
   [-3] context table
   [-2] callback
   [-1] self
In the event of an unsuccessful call, the Lua stack is unchanged

PARAMETERS

cbk Lua callback struct

RETURNS

if the setup was successful

dmScript::TeardownCallback

void dmScript::TeardownCallback( cbk)

Sets the previous instance Expects Lua stack: 

   [-2] old instance
   [-1] context table
Both values are removed from the stack

PARAMETERS

cbk Lua callback struct

dmScript::PCall

 dmScript::PCall( L,  nargs,  nresult)

This function wraps lua_pcall with the addition of specifying an error handler which produces a backtrace. In the case of an error, the error is logged and popped from the stack.

PARAMETERS

L lua state
nargs number of arguments
nresult number of results

RETURNS

code from pcall

RefInInstance

int RefInInstance(lua_State* L)

Creates a reference to the value at top of stack, the ref is done in the current instances context table. Expects SetInstance() to have been set with an value that has a meta table with META_GET_INSTANCE_CONTEXT_TABLE_REF method.

PARAMETERS

lua_State* L Lua state

RETURNS

int ref to value or LUA_NOREF Lua stack on entry [-1] value Lua stack on exit

UnrefInInstance

void UnrefInInstance(lua_State* L, int ref)

Deletes the instance local lua reference Expects SetInstance() to have been set with an value that has a meta table with META_GET_INSTANCE_CONTEXT_TABLE_REF method.

PARAMETERS

lua_State* L Lua state
int ref ref to value or LUA_NOREF Lua stack on entry Lua stack on exit

RefInInstance

dmMessage::Result RefInInstance(lua_State* L, const char* url, dmMessage::URL* out_url, dmMessage::URL* default_url)

Resolves a url in string format into a dmMessage::URL struct. Special handling for: - "." returns the default socket + path - "#" returns default socket + path + fragment

PARAMETERS

lua_State* L Lua state
const char* url url
dmMessage::URL* out_url where to store the result
dmMessage::URL* default_url default url

RETURNS

dmMessage::Result dmMessage::RESULT_OK if the conversion succeeded

UrlToString

const char* UrlToString(dmMessage::URL* url, char* buffer, uint32_t buffer_size)

Converts a URL into a readable string. Useful for e.g. error messages

PARAMETERS

dmMessage::URL* url url
char* buffer the output buffer
uint32_t buffer_size the output buffer size

RETURNS

const char* returns the passed in buffer

Structs

dmScript::LuaHBuffer

TYPE

struct dmScript::LuaHBuffer

Holds info about the buffer and who owns it.

MEMBERS

Union of - m_BufferRes void* A buffer resource - m_Buffer dmBuffer::HBuffer A buffer
dmBuffer::HBuffer m_Buffer The buffer (or resource)
dmScript::LuaBufferOwnership m_Owner What ownership the pointer has

dmScript::LuaCallbackInfo

TYPE

struct dmScript::LuaCallbackInfo

callback info struct that will hold the relevant info needed to make a callback into Lua

Types

HContext

The script context

Enums

LuaBufferOwnership

Buffer ownership. - OWNER_C - m_Buffer is owned by C side, should not be destroyed when GCed - OWNER_LUA - m_Buffer is owned by Lua side, will be destroyed when GCed - OWNER_RES - m_Buffer not used, has a reference to a buffer resource instead. m_BufferRes is owned by C side, will be released when GCed

dmScript::OWNER_C
dmScript::OWNER_LUA
dmScript::OWNER_RES

Macros

DM_LUA_STACK_CHECK

Diff is the expected difference of the stack size. If luaL_error, or another function that executes a long-jump, is part of the executed code, the stack guard cannot be guaranteed to execute at the end of the function. In that case you should manually check the stack using lua_gettop. In the case of luaL_error, see DM_LUA_ERROR.

L lua state
diff Number of expected items to be on the Lua stack once this struct goes out of scope

EXAMPLES

DM_LUA_STACK_CHECK(L, 1);
lua_pushnumber(L, 42);

DM_LUA_ERROR

This macro will verify that the Lua stack size hasn't been changed before throwing a Lua error, which will long-jump out of the current function. This macro can only be used together with DM_LUA_STACK_CHECK and should be prefered over manual checking of the stack.

fmt Format string that contains error information.
args Format string args (variable arg list)

EXAMPLES

static int ModuleFunc(lua_State* L)
{
    DM_LUA_STACK_CHECK(L, 1);
    if (some_error_check(L))
    {
        return DM_LUA_ERROR("some error message");
    }
    lua_pushnumber(L, 42);
    return 1;
}