Sdk script api documentation

Built-in scripting functions.

Namespace: dmScript
Include: #include <dmsdk/script/script.h>
STRUCTS
struct dmScript::LuaCallbackInfo callback info struct
FUNCTIONS
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...
Vectormath::Aos::Vector3* dmScript::ToVector3(lua_State* L, int index) get the value at index as a Vectormath::Aos::Vector3*
 dmScript::IsVector3( L,  index) Check if the value at #index is a Vectormath::Aos:...
void dmScript::PushVector3(lua_State* L, Vectormath::Aos::Vector3 v) push a Vectormath::Aos::Vector3 onto the Lua stack
Vectormath::Aos::Vector3* dmScript::CheckVector3(lua_State* L, int index) check if the value is a Vectormath::Aos::Vector3
Vectormath::Aos::Vector4* dmScript::ToVector4(lua_State* L, int index) get the value at index as a Vectormath::Aos::Vector4*
 dmScript::IsVector4( L,  index) Check if the value at #index is a Vectormath::Aos:...
void dmScript::PushVector4(lua_State* L, Vectormath::Aos::Vector4 v) push a Vectormath::Aos::Vector4 on the stack
Vectormath::Aos::Vector4* dmScript::CheckVector4(lua_State* L, int index) check if the value is a Vectormath::Aos::Vector3
Vectormath::Aos::Quat* dmScript::ToQuat(lua_State* L, int index) get the value at index as a Vectormath::Aos::Quat*
void dmScript::PushQuat(lua_State* L, Vectormath::Aos::Quat quat) push a Vectormath::Aos::Quat onto the Lua stack
Vectormath::Aos::Quat* dmScript::CheckQuat(lua_State* L, int index) check if the value is a Vectormath::Aos::Vector3
Vectormath::Aos::Matrix4* dmScript::ToMatrix4(lua_State* L, int index) get the value at index as a Vectormath::Aos::Matrix4*
void dmScript::PushMatrix4(lua_State* L, Vectormath::Aos::Matrix4 matrix) push a Vectormath::Aos::Matrix4 onto the Lua stack
Vectormath::Aos::Matrix4* dmScript::CheckMatrix4(lua_State* L, int index) check if the value is a Vectormath::Aos::Matrix4
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...
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

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

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

Get the value at index as a Vectormath::Aos::Vector3*

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

Vectormath::Aos::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 Vectormath::Aos::Vector3*

PARAMETERS

L Lua state
index Index of the value

RETURNS

if value at #index is a Vectormath::Aos::Vector3*

dmScript::PushVector3

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

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

PARAMETERS

lua_State* L Lua state
Vectormath::Aos::Vector3 v Vector3 value to push

dmScript::CheckVector3

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

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

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

Vectormath::Aos::Vector3* The pointer to the value

dmScript::ToVector4

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

Get the value at index as a Vectormath::Aos::Vector4*

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

Vectormath::Aos::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 Vectormath::Aos::Vector4*

PARAMETERS

L Lua state
index Index of the value

RETURNS

if value at #index is a Vectormath::Aos::Vector4*

dmScript::PushVector4

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

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

PARAMETERS

lua_State* L Lua state
Vectormath::Aos::Vector4 v Vectormath::Aos::Vector4 value to push

dmScript::CheckVector4

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

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

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

Vectormath::Aos::Vector4* The pointer to the value

dmScript::ToQuat

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

Get the value at index as a Vectormath::Aos::Quat*

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

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

dmScript::PushQuat

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

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

PARAMETERS

lua_State* L Lua state
Vectormath::Aos::Quat quat Vectormath::Aos::Quat value to push

dmScript::CheckQuat

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

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

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

Vectormath::Aos::Quat* The pointer to the value

dmScript::ToMatrix4

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

Get the value at index as a Vectormath::Aos::Matrix4*

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

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

dmScript::PushMatrix4

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

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

PARAMETERS

lua_State* L Lua state
Vectormath::Aos::Matrix4 matrix Vectormath::Aos::Matrix4 value to push

dmScript::CheckMatrix4

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

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

PARAMETERS

lua_State* L Lua state
int index Index of the value

RETURNS

Vectormath::Aos::Matrix4* The pointer to the value

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

Structs

dmScript::LuaCallbackInfo

TYPE

struct dmScript::LuaCallbackInfo

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

Macros

DM_LUA_STACK_CHECK

helper macro to validate the Lua stack state before leaving a function.

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

helper macro to validate the Lua stack state and throw a 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;
}