GLUT鼠标按钮向下

Question

只要按住鼠标右键，我就想放大一个物体。现在的问题是我每次想要缩放都要点击它。有没有办法可以修改我的代码，以便在按住按钮时进行缩放，而不是单击它？

void mouse(int button, int state, int x, int y)
{
    // Save the left button state
    if (button == GLUT_LEFT_BUTTON)
    {
        leftMouseButtonDown = (state == GLUT_DOWN);
        zMovement += 0.1f;
    }

    else if (button == GLUT_RIGHT_BUTTON)
    {
        leftMouseButtonDown = (state == GLUT_DOWN);
        zMovement -= 0.1f;
    }

    // Save the mouse position
    mouseXPos = x;
    mouseYPos = y;
}

Answer 1

函数的状态变量告诉你发生了什么类型的鼠标按钮事件：它可以是GLUT_DOWN或GLUT_UP。

了解这一点，只要状态设置为true，就可以将此状态存储在鼠标函数之外的额外变量中并进行缩放（这必须在每个帧的某处完成）。代码可能如下所示：

void mouse(int button, int state, int x, int y)
{
    // Save the left button state
    if (button == GLUT_LEFT_BUTTON)
    {
        leftMouseButtonDown = (state == GLUT_DOWN);
    }

    else if (button == GLUT_RIGHT_BUTTON)
    {
        // \/ right MouseButton
        rightMouseButtonDown = (state == GLUT_DOWN);
    }

    // Save the mouse position
    mouseXPos = x;
    mouseYPos = y;
}

void callThisInEveryFrame()
{
    if (leftMouseButtonDown)
        zMovement += 0.1f;
    if (rightMouseButtonDown)
        zMovement -= 0.1f;
}