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C使用角度度和三角绘制多边形

trigonometry gdi+ c#

jb. · 技术社区 · 15 年前

我使用下面的方法来计算六边形的顶点,然后做一个简单的 graphics.DrawPolygon(pen, aptsVertices) 以后再画。

protected override void CalculateVertices()
{
    //member variables
    aptsVertices = new Point[6];
    deg = 120;
    rad = deg * (Math.PI / 180);

    double nSinDeg = Math.Sin(rad);
    double nCosDeg = Math.Cos(rad);

    aptsVertices[0] = ptFirstVertex;

    for(int i = 1; i < aptsVertices.Length; i++)
    {
        double x = aptsVertices[i - 1].X - nCosDeg * nSideLength;
        double y = aptsVertices[i - 1].Y - nSinDeg * nSideLength;
        aptsVertices[i] = new Point((int)x, (int)y);

        //recalculate the degree for the next vertex
        deg += 120;
        rad = deg * (Math.PI / 180);

        nSinDeg = Math.Sin(rad);
        nCosDeg = Math.Cos(rad);
    }
}

4 回复 | 直到 13 年前

digEmAll 15 年前

deg += 120 deg step = 60Â°

public static Point[] CalculateVertices(int nSides, int nSideLength, Point ptFirstVertex)
{
    if (nSides < 3)
        throw new ArgumentException("Polygons can't have less than 3 sides...");

    var aptsVertices = new Point[nSides];
    var deg = (180.0 * (nSides - 2)) / nSides;
    var step = 360.0 / nSides;
    var rad = deg * (Math.PI / 180);

    double nSinDeg = Math.Sin(rad);
    double nCosDeg = Math.Cos(rad);

    aptsVertices[0] = ptFirstVertex;

    for (int i = 1; i < aptsVertices.Length; i++)
    {
        double x = aptsVertices[i - 1].X - nCosDeg * nSideLength;
        double y = aptsVertices[i - 1].Y - nSinDeg * nSideLength;
        aptsVertices[i] = new Point((int)x, (int)y);


        //recalculate the degree for the next vertex
        deg -= step;
        rad = deg * (Math.PI / 180);

        nSinDeg = Math.Sin(rad);
        nCosDeg = Math.Cos(rad);

    }
    return aptsVertices;
}

sanjoyd 15 年前

point [i] = new Point (center.x + sideLength * cos ((Math.PI * i) / 6), center.y + sideLength * sin ((Math.PI * i) / 6));

jpreed00 14 年前

public static PointD[] CalculateVertices(int nSides, int nSideLength, PointD ptFirstVertex)
{
    //calculate the points for a polygon of N sides
    if (nSides < 3)
        throw new ArgumentException("Polygons can't have less than 3 sides...");

    var aptsVertices = new PointD[nSides];
    var deg = (180.0 * (nSides - 2)) / nSides;
    var step = 360.0 / nSides;
    var rad = deg * (Math.PI / 180);

    double nSinDeg = Math.Sin(rad);
    double nCosDeg = Math.Cos(rad);

    aptsVertices[0] = ptFirstVertex;

    for (int i = 1; i < aptsVertices.Length; i++)
    {
        double x = aptsVertices[i - 1].X - nCosDeg * nSideLength;
        double y = aptsVertices[i - 1].Y - nSinDeg * nSideLength;
        aptsVertices[i] = new PointD(x, y);

        //recalculate the degree for the next vertex
        deg -= step;
        rad = deg * (Math.PI / 180);

        nSinDeg = Math.Sin(rad);
        nCosDeg = Math.Cos(rad);

    }
    return aptsVertices;
}

public class PointD
{
    public double X, Y;
    public PointD(double _x, double _y)
    {
        X = _x;
        Y = _y;
    }
}

coopersita 13 年前

-(NSArray *) calculateVertices:(int)numSides center:(CGPoint)ctr{
NSMutableArray *vertices = [[NSMutableArray alloc] init];

if (numSides < 3) {
    return vertices;
}

float deg = ((180.0 * (numSides-2) / numSides)-180)/2;

float step = 360.0 / numSides;
float rad = deg * (M_PI / 180);

double nSinDeg = sin(rad);
double nCosDeg = cos(rad);

int sl = [self calculateSideLength:numSides];

CGPoint firstPoint = CGPointMake(ctr.x, ctr.y-radius);    
[vertices addObject:[NSValue valueWithCGPoint:firstPoint]];

for (int i = 1; i < numSides; i++) {
    NSValue *vp = [vertices objectAtIndex:i-1];
    CGPoint pp =[vp CGPointValue];
    double x = pp.x - nCosDeg * sl;
    double y = pp.y - nSinDeg * sl;
    CGPoint np = CGPointMake(x, y);
    [vertices addObject:[NSValue valueWithCGPoint:np]];

    deg -= step;
    rad = deg * (M_PI / 180);

    nSinDeg = sin(rad);
    nCosDeg = cos(rad);

}

return vertices;

}

-(int) calculateSideLength:(int)numSides{
   int length = (2*radius)*sin(M_PI/numSides);
   return length;
}