Variable Export
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:
16.08.2019
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