Variable Export
Warning
The scope of applications for UnigineScript is limited to implementing materials-related logic (material expressions, scriptable materials, brush materials). Do not use UnigineScript as a language for application logic, please consider C#/C++ instead, as these APIs are the preferred ones. Availability of new Engine features in UnigineScipt (beyond its scope of applications) is not guaranteed, as the current level of support assumes only fixing critical issues.
To use variables from your C++ code in UnigineScript, you need to export them. After that, they will be available on the script side.
- External variables are read-only.
- If a value of a registered variable is changed in the C++ code, it instantly changes in the script as well (unlike in case of constants).
See also#
An example can be found in <UnigineSDK>/source/samples/Api/Scripts/Variable/ directory.
Variable Export Example#
Let's say, you declared a number of variables on C++ side. To export them, you will need to do the following:
- Create a pointer to an external variable via MakeExternVariable().
- Register the variable via Unigine::Interpreter::addExternVariable().
- All variables are exported into a global namespace. To limit the scope of variable, use library namespace.
Source code (C++)
#include <UnigineInterpreter.h>
#include <UnigineInterface.h>
using namespace Unigine;
int main(int argc,char **argv) {
int i = 2;
float f = 1.5f;
vec3 v3 = vec3(1.0f,2.0f,3.0f);
vec4 v4 = vec4(0.1f,0.2f,0.3f,0.4f);
float m[16] = { 0.0f, 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f, 7.0f,\
8.0f, 9.0f, 10.0f, 11.0f, 12.0f, 13.0f, 14.0f, 15.0f };
mat4 mat = mat4(m);
quat q = quat(0.0f,0.0f,1.0f,0.0f);
// export a variable and specify a name to access it from Unigine scripts
Interpreter::addExternVariable("integer",MakeExternVariable(&i));
Interpreter::addExternVariable("float_point",MakeExternVariable(&f));
Interpreter::addExternVariable("vector3",MakeExternVariable(&v3));
Interpreter::addExternVariable("vector4",MakeExternVariable(&v4));
Interpreter::addExternVariable("matrix4",MakeExternVariable(&mat));
Interpreter::addExternVariable("quaternion",MakeExternVariable(&q));
Engine *engine = Engine::init(UNIGINE_VERSION,argc,argv);
// enter the main loop
while(engine->isDone() == 0) {
engine->update();
engine->render();
engine->swap();
// if a variable value is changed after it was registered, in scripts the value will be changed as well
i = 42;
}
// engine shutdown
Engine::shutdown();
}Access from Scripts#
After the registration, you can access variables from a script by their registered names:
Source code (UnigineScript)
// my_world.usc
int init() {
log.message("Integer is %d\nFloat is %f\n",integer,float_point);
log.message("Vector3 x is %f\nVector3 y is %f\n",vector3.x,vector3.y);
log.message("Vector4 w is %f\n",vector4.w);
log.message("Matrix4 m10 is %f\nMatrix4 m11 is %f\n",matrix4.m10,matrix4.m11);
return 1;
}Output#
The following results will be printed into the console after launching the application:
Output
Integer is 2
Float is 1.500000
Vector3 x is 1.000000
Vector3 y is 2.000000
Vector4 w is 0.400000
Matrix4 m10 is 1.000000
Matrix4 m11 is 5.000000If you reload the world, the integer value that has been changed on the C++ side will appear in the console:
Output
Integer is 42
Float is 1.500000
Vector3 x is 1.000000
Vector3 y is 2.000000
Vector4 w is 0.400000
Matrix4 m10 is 1.000000
Matrix4 m11 is 5.000000Last update:
09.04.2021
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