(Windows C++) How to simulate mouse movement in FPS games?

Question

I'm trying to simulate mouse movement in FPS games, more specifically Valorant. I am aware of the SetCursorPos() function and the mouse_event() function, which both work fine for changing the cursor's position. This works in FPS games that use the technique of constantly centering the cursor, but Valorant doesn't seem to do that. I wrote a program to constantly check my cursor's position (using GetCursorPos()) and my cursor never got centered, if I moved the mouse to a corner and then kept moving it, my character kept rotating. So, how does Valorant sense that I'm moving my mouse when my cursor's position isn't changing, and how can I counter that and simulate mouse movement in Valorant?

By the way, don't worry - I'm not trying to cheat, just trying to make smooth motions in freecam for cinematic shots.

Answer 1

I'm not sure how Valorant is implemented, but I can use the RegisterRawInputDevices to get the mouse event when the cursor's position isn't changing:

#include <windows.h>
#include <iostream>

using namespace std;
BOOL registerTouchpadForInput(HWND hWnd)
{
    RAWINPUTDEVICE rid;
    rid.dwFlags = RIDEV_NOLEGACY | RIDEV_INPUTSINK;
    rid.usUsagePage = 1;                            
    rid.usUsage = 2;
    rid.hwndTarget = hWnd;
    return RegisterRawInputDevices(&rid, 1, sizeof(rid));
}

static LRESULT CALLBACK NVTouch_WindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    BOOL  registrationStatus = false;
    switch (message)
    {
    case WM_CREATE:
        registrationStatus = registerTouchpadForInput(hwnd);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    case WM_INPUT:
        printf("WM_INPUT ");
        return DefWindowProc(hwnd, message, wParam, lParam);
    default:
        return DefWindowProc(hwnd, message, wParam, lParam);
    }
    return 0;
}

int main()
{
    WNDCLASSEX wndclass = {
        sizeof(WNDCLASSEX),
        CS_DBLCLKS,
        NVTouch_WindowProc,
        0,
        0,
        GetModuleHandle(0),
        LoadIcon(0,IDI_APPLICATION),
        LoadCursor(0,IDC_ARROW),
        HBRUSH(COLOR_WINDOW + 1),
        0,
        L"myclass",
        LoadIcon(0,IDI_APPLICATION)
    };
    bool isClassRegistered = false;
    isClassRegistered = RegisterClassEx(&wndclass);
    if (isClassRegistered)
    {
        HWND window = CreateWindow(wndclass.lpszClassName, NULL, 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, GetModuleHandle(0), NULL);
        if (window)
        {
            ShowWindow(window, SW_SHOWDEFAULT);
            MSG msg;
            while (GetMessage(&msg, 0, 0, 0))
            {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
            }
        }
    }
}

And then, use SendInput to simulate the relative mouse move at the border of the screen:

INPUT buffer;
ZeroMemory(&buffer, sizeof(buffer));
buffer.type = INPUT_MOUSE;
buffer.mi.dx = 10;
buffer.mi.dy = 10;
buffer.mi.mouseData = 0;
buffer.mi.dwFlags = MOUSEEVENTF_MOVE;
buffer.mi.time = 0;
buffer.mi.dwExtraInfo = 0;
while (1)
{
    Sleep(1000);
    SendInput(1, &buffer, sizeof(INPUT));
}