raylib_dpi_hack.c

Vector2 GetWindowDPI(void)
{
    float xdpi = 1.0;
    float ydpi = 1.0;

#if defined(PLATFORM_DESKTOP)
    Vector2 windowPos = GetWindowPosition();
    
    int monitorCount;
    GLFWmonitor **monitors = glfwGetMonitors (&monitorCount);

    for(int i = 0; i < monitorCount; i++) {
        glfwGetMonitorContentScale(monitors[i], &xdpi, &ydpi);
        int xpos, ypos, width, height;
        
        glfwGetMonitorWorkarea(monitors[i], &xpos, &ypos, &width, &height);
        
        if(windowPos.x >= xpos
           && windowPos.x < xpos + width
           && windowPos.y >= ypos
           && windowPos.y < ypos + height) {
            return (Vector2) { xdpi, ydpi };
        }
    }

#endif
    return (Vector2){ 1.0, 1.0 };
}

// Later in your drawing code:
    Vector2 scale = GetWindowDPI();

    extern void rlViewport(int x, int y, int width, int height);
    rlViewport(0, 0, VIEWPORT_WIDTH * scale.x, VIEWPORT_HEIGHT * scale.y);