问题描述
我有个任务绘制特定图形。由于这个任务,我需要在旋转45度的一些点的一部分。
I have a task to draw a specific graphic. As part of this task I need to rotate some dot's on 45 degrees.
我已经花了2天尝试计算公式,但只是无法得到它对。
我一直在寻找全国各地,包括这个特定的网站,我已经非常接近,但我仍然不存在。
I've spent already 2 days trying to calculate a formula, but just couldn't get it right.I've been searching all over the place including this particular website, I'm getting very close, but I'm still not there.
这地方是:
我需要绘制4个不同的点
Here it is:I need to draw 4 different points
我有一个特定的公式来计算有位置,这是出了问题的范围,但这里是什么我得到作为它的结果:
I have a specific formula to calculate there position, which is out of scope of the question, but here is what I'm getting as a result of it:
int radius = 576;
int diameter = radius * 2;
Point blueA = new Point(561, 273);
Point greenB = new Point(273, 561);
Point yellowC = new Point (849, 561);
Point redD = new Point (561, 849);
现在我需要在45度旋转,这点。我用下面的代码来实现它:
Now I need to rotate this dots on 45 degrees. I use the following code to achieve it:
double rotationAngle = 45;
double rotationRadians = rotationAngle * (Math.PI / 180);
int center = radius;
result.X = (int)(Math.Cos(rotationRadians) * ((double)result.X - (double)center) - (double)Math.Sin(rotationRadians) * ((double)result.Y - center) + (double)center);
result.Y = (int)(Math.Sin(rotationRadians) * ((double)result.X - (double)center) + (double)Math.Cos(rotationRadians) * ((double)result.Y - center) + (double)center);
但是,这就是我得到:
But that's what I'm getting:
任何帮助将不胜感激
推荐答案
问题是 INT中心=半径
为其设置 INT半径= 576
。因为肯定你绕应该有一个X和Y位置的点这是没有意义的。
The problem is int center = radius
which you are setting int radius = 576
. This doesn't make sense as surely you are rotating about a point that should have an x and y location.
给你周围的起源中心 X
和是既要为
0
不是 576
。
Given you are rotating around the origin the center
x
and y
should both be 0
not 576
.
因此,鉴于这种情况,试试这个
So, given that, try this.
/// <summary>
/// Rotates one point around another
/// </summary>
/// <param name="pointToRotate">The point to rotate.</param>
/// <param name="centerPoint">The center point of rotation.</param>
/// <param name="angleInDegrees">The rotation angle in degrees.</param>
/// <returns>Rotated point</returns>
static Point RotatePoint(Point pointToRotate, Point centerPoint, double angleInDegrees)
{
double angleInRadians = angleInDegrees * (Math.PI / 180);
double cosTheta = Math.Cos(angleInRadians);
double sinTheta = Math.Sin(angleInRadians);
return new Point
{
X =
(int)
(cosTheta * (pointToRotate.X - centerPoint.X) -
sinTheta * (pointToRotate.Y - centerPoint.Y) + centerPoint.X),
Y =
(int)
(sinTheta * (pointToRotate.X - centerPoint.X) +
cosTheta * (pointToRotate.Y - centerPoint.Y) + centerPoint.Y)
};
}
使用像这样。
Point center = new Point(0, 0);
Point newPoint = RotatePoint(blueA, center, 45);
如果中心点总是很显然
0,0
则可以相应地简化功能,否则使中心点通过默认的参数可选,或者通过重载方法。你也可能会想要封装了一些可重复使用的数学到其他静态方法了。
Obviously if the center point is always
0,0
then you can simplify the function accordingly, or else make the center point optional via a default parameter, or by overloading the method. You would also probably want to encapsulate some of reusable the math into other static methods too.
例如
/// <summary>
/// Converts an angle in decimal degress to radians.
/// </summary>
/// <param name="angleInDegrees">The angle in degrees to convert.</param>
/// <returns>Angle in radians</returns>
static double DegreesToRadians(double angleInDegrees)
{
return angleInDegrees * (Math.PI / 180);
}
/// <summary>
/// Rotates a point around the origin
/// </summary>
/// <param name="pointToRotate">The point to rotate.</param>
/// <param name="angleInDegrees">The rotation angle in degrees.</param>
/// <returns>Rotated point</returns>
static Point RotatePoint(Point pointToRotate, double angleInDegrees)
{
return RotatePoint(pointToRotate, new Point(0, 0), angleInDegrees);
}
使用像这样。
Point newPoint = RotatePoint(blueA, 45);
最后,如果您使用的是GDI,你也可以简单地做一个
RotateTransform
。
请参阅:
Graphics g = this.CreateGraphics();
g.TranslateTransform(blueA);
g.RotateTransform(45);
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