Project Chrono 0xC0000005 Crash - Access violation on vehicle.Initialize() (Custom JSON Loading Issue)
Emrullah Cebeci
Hello, I am trying to load a custom vehicle in Project Chrono using JSON files, but I am receiving a 0xC0000005: Access violation (Null Pointer) error that I cannot solve.
The program always crashes when it reaches the vehicle.Initialize(...) line. This indicates that the WheeledVehicle constructor failed, and the vehicle object is being created as a null pointer (nullptr).
I believe the file references in my JSON files and my main.cpp code are correct. My JSON file structure is as follows: C:/Projects/vehicle_project/data/temp/vehicle/vehicle.json
Here is the relevant section of my main.cpp:
#include "chrono_vehicle/ChVehicleModelData.h"
// ... other includes ...
using namespace chrono;
using namespace chrono::vehicle;
int main() {
// SetDataPath points to the 'data' directory from the file tree above
const std::string vehicle_data_path = "C:/Projects/vehicle_project/data";
chrono::vehicle::SetDataPath(vehicle_data_path);
// The vehicle JSON is called relative to the 'data' directory
const std::string vehfile = "temp/vehicle/Vehicle.json";
WheeledVehicle vehicle(vehfile, ChContactMethod::SMC, false, false);
// THE ERROR OCCURS ON THIS EXACT LINE
vehicle.Initialize(ChCoordsys<>(ChVector3d(0, 0, 0.6), QuatFromAngleZ(0)));
// ... (rest of the code)
}
I would greatly appreciate it if you could tell me what is causing this problem and how to solve it. Thank you.
Radu Serban
This kind of issues are difficult to debug without a full working example.
My suspicion is that some JSON file is not found as expected. Note that the JSON files referenced from the top-level vehicle JSON file must be provided relative to the vehicle data directory.
But all of this is not that relevant. Such an issue can *very* easily be identified by building the code in *Debug* mode and stepping through it with a debugger. Step through each subsystem constructor and ensure that the JSON file it attempts to use is what you expect. Have you done that?
Radu
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Emrullah Cebeci
Yes, I did what you suggested. When I debugged the code, I noticed that the 'vehicle.json' file could not be read, and the system was returning a null value. I checked the location and content of all other files referenced in the 'vehicle.json' file and could not see any issues.
Initially, I thought the GetDataFile function wasn't returning the correct file directory. However, I encountered the same problem even when I bypassed that function and manually hard-coded the direct path into the code.
To check if the problem was with the JSON files I created, I tried using the standard HMMWV JSON files that come with the Chrono installation, but the issue persisted.