xna使用鼠标滚轮缩放

Question

如何使用鼠标滚轮进行缩放,我试试这个

        if (currentMouseState.ScrollWheelValue < originalMouseState.ScrollWheelValue)
        {
            cameraPosition += new Vector3(0, -1, 0);
            UpdateViewMatrix();
            currentMouseState.ScrollWheelValue.Equals(0);
        }
        if (currentMouseState.ScrollWheelValue > originalMouseState.ScrollWheelValue)
        {
            cameraPosition += new Vector3(0, 1, 0);
            UpdateViewMatrix();
            currentMouseState.ScrollWheelValue.Equals(0);
        }

但即使我滚动一次,我仍然继续放大,我对XNA有点新意.请帮忙.

Answer 1

ScrollWheelValue 从游戏开始以来获取累积鼠标滚轮值,因此每次获得它时,您需要将该值复制到变量中,以便在下一个循环中进行比较.

而且,你不能设置ScrollWheelValue,这一行是错误的:

currentMouseState.ScrollWheelValue.Equals(0);

我认为你的想法是将其值设置为0,但该指令将其值与0进行比较并给出一个布尔值.

编辑:
你应该做这样的事情:

声明一个全局变量

private int previousScrollValue;

并在Initialize方法中设置为:

previousScrollValue = originalMouseState.ScrollWheelValue;

然后编辑您的代码:

if (currentMouseState.ScrollWheelValue < previousScrollValue)
{
    cameraPosition += new Vector3(0, -1, 0);
    UpdateViewMatrix();
}
else if (currentMouseState.ScrollWheelValue > previousScrollValue)
{
    cameraPosition += new Vector3(0, 1, 0);
    UpdateViewMatrix();
}
previousScrollValue = currentMouseState.ScrollWheelValue;

它应该工作.