移动鼠标时抖动 [英] Jittering when moving mouse

问题描述

我有一个 opengl 程序，我正在使用 SDL 进行窗口创建/事件处理等.现在，当我移动鼠标以重新定位摄像机偏航/俯仰时，我得到一个抖动的图像，旧位置闪烁在屏幕上一瞬间.

I have an opengl program and I am using SDL for the window creating / event handling etc. Now, when I move the mouse to re-position the cameras yaw/pitch, I get a jittering image, with the old position flashing on the screen for a split second.

现在我认为这可能是我重新定位鼠标的方式的问题.在重新定位结束时，我将其设置回屏幕的中心.这是上述代码:

Now i think this may be an issue with the way I re-position the mouse. I have it set back to the center of the screen at the end of the re-positioning. Here is the said code:

void handleMouseMove(int mouseX, int mouseY)
{
    GLfloat vertMouseSensitivity  = 10.0f;
    GLfloat horizMouseSensitivity = 10.0f;

    int horizMovement = mouseX - midWindowX;
    int vertMovement  = mouseY - midWindowY;

    camXRot += vertMovement / vertMouseSensitivity;
    camYRot += horizMovement / horizMouseSensitivity;

    if (camXRot < -90.0f)
    {
        camXRot = -90.0f;
    }

    if (camXRot > 90.0f)
    {
        camXRot = 90.0f;
    }

    if (camYRot < -180.0f)
    {
        camYRot += 360.0f;
    }

    if (camYRot > 180.0f)
    {
        camYRot -= 360.0f;
    }

    // Reset the mouse to center of screen
    SDL_WarpMouse(midWindowX, midWindowY);
}

现在，在我的主 while 循环中，这是调用此函数的 SDL 代码:

Now, Inside my main while loop, here is the SDL code for calling this function:

while( SDL_PollEvent( &event ) )
        {
            if( event.type == SDL_KEYDOWN )
            {
                if( event.key.keysym.sym == SDLK_ESCAPE )
                {
                    Game.running = false;
                }
            }
            if( event.type == SDL_MOUSEMOTION )
            {
                int mouse_x, mouse_y;
                SDL_GetMouseState(&mouse_x, &mouse_y);

                handleMouseMove(mouse_x, mouse_y);
            }

我发现像这样获取坐标 event.motion.x 和 event.motion.x 造成的这种影响较小.

I found that getting the coordinates like this verses event.motion.x and event.motion.x caused less of this effect.

关于如何避免这种抖动"图像​​的任何想法?

Any thoughts on how I could avoid this 'jittering' image?

推荐答案

当您SDL_WarpMouse 时，会生成另一个鼠标移动事件，您正在再次处理该事件.你必须忽略第二个.

When you SDL_WarpMouse, another mouse move event is generated that you are handling again. You must ignore the second one.

为了让事情变得更复杂，并不是每个运动事件都跟随着由 SDL_WarpMouse 引起的相反方向的一个事件.事件可能来自例如两个运动和 1 个由扭曲到屏幕中间产生的运动.我写了这段对我有用的代码:

To make things more complicated, it's not like every motion event is followed by one in the opposite direction caused by SDL_WarpMouse. The events may come for example two motions and 1 generated by warp to the middle of the screen. I have written this code which works for me:

void motion(SDL_MouseMotionEvent *mme)
{
    static bool initializing = true;  // For the first time
    static int warpMotionX = 0, warpMotionY = 0;  // accumulated warp motion
    if (initializing)
    {
        if (mme->x == midWindowX && mme->y == midWindowY)
            initializing = false;
        else
            SDL_WarpMouse(midWindowX, midWindowY);
    }
    else if (mme->xrel != -warpMotionX || mme->yrel != -warpMotionY)
    {
        /****** Mouse moved by mme->xrel and mme->yrel ******/
        warpMotionX += mme->xrel;
        warpMotionY += mme->yrel;
        SDL_WarpMouse(midWindowX, midWindowY);
    }
    else    // if event motion was negative of accumulated previous moves,
            // then it is generated by SDL_WarpMotion
        warpMotionX = warpMotionY = 0;
}

void processEvents()
{
    SDL_Event e;
    while (SDL_PollEvent(&e))
    {
        switch (e.type)
        {
            case SDL_MOUSEMOTION:
                motion(&e.motion);
                break;
            default:
                break;
        }
    }
}

请注意，我自己对 -mme->yrel 比 mme->yrel 感兴趣，这就是为什么它在原始代码中我在任何地方都否定它我使用它(我在上面发布的代码中删除了它)

Note that, I myself am interested in -mme->yrel than mme->yrel and that's why it's in the original code I have it negated wherever I use it (I removed it in the code I posted above)

我写的地方 /****** Mouse move by mme->xrel and mme->yrel ******/ 是你想要对鼠标进行操作的地方运动.其他代码是忽略由 SDL_WarpMouse

Where I wrote /****** Mouse moved by mme->xrel and mme->yrel ******/ is where you want to act on the mouse motion. Other code is to ignore motion generated by SDL_WarpMouse

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