OpenSpace/modules/base/scale/luascale.cpp

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2018                                                               *
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#include <modules/base/scale/luascale.h>

#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>
#include <openspace/util/updatestructures.h>

#include <ghoul/lua/ghoul_lua.h>
#include <ghoul/lua/lua_helper.h>
#include <ghoul/filesystem/filesystem.h>

#include <chrono>

namespace {
    static const openspace::properties::Property::PropertyInfo ScriptInfo = {
        "Script",
        "Script",
        "This value is the path to the Lua script that will be executed to compute the "
        "scaling factor for this transformation. The script needs to define a function "
        "'scale' that takes the current simulation time in seconds past the J2000 epoch "
        "as the first argument, the current wall time as milliseconds past the J2000 "
        "epoch the second argument and computes the scaling factor."
    };
} // namespace

namespace openspace {

documentation::Documentation LuaScale::Documentation() {
    using namespace openspace::documentation;
    return {
        "Lua Scaling",
        "base_scale_lua",
        {
            {
                ScriptInfo.identifier,
                new StringVerifier,
                Optional::No,
                ScriptInfo.description
            }
        }
    };
}

LuaScale::LuaScale()
    : _luaScriptFile(ScriptInfo)
    , _state(false)
{
    addProperty(_luaScriptFile);
}

LuaScale::LuaScale(const ghoul::Dictionary& dictionary)
    : LuaScale()
{
    documentation::testSpecificationAndThrow(Documentation(), dictionary, "LuaScale");

    _luaScriptFile = absPath(dictionary.value<std::string>(ScriptInfo.identifier));
}

void LuaScale::update(const UpdateData& data) {
    ghoul::lua::runScriptFile(_state, _luaScriptFile);

    // Get the scaling function
    lua_getglobal(_state, "scale");
    bool isFunction = lua_isfunction(_state, -1);
    if (!isFunction) {
        LERRORC(
            "LuaScale",
            "Script '" << _luaScriptFile << "' does not have a function 'scale'"
        );
        return;
    }

    // First argument is the number of seconds past the J2000 epoch in ingame time
    lua_pushnumber(_state, data.time.j2000Seconds());

    // Second argument is the number of milliseconds past the J2000 epoch in wallclock
    using namespace std::chrono;
    auto now = high_resolution_clock::now();
    lua_pushnumber(
        _state,
        static_cast<lua_Number>(
            duration_cast<milliseconds>(now.time_since_epoch()).count()
        )
    );

    // Execute the scaling function
    int success = lua_pcall(_state, 2, 1, 0);
    if (success != 0) {
        LERRORC(
            "LuaScale",
            "Error executing 'scale': " << lua_tostring(_state, -1)
        );
    }

    _scale = luaL_checknumber(_state, -1);
}

} // namespace openspace