public static VertexPositionColor[] GetCircleVertices(int radius, int angleInDegrees, out int primitiveCount, AlignmentPlaneType orientationType)
{
primitiveCount = 360 / angleInDegrees;
VertexPositionColor[] vertices = new VertexPositionColor[primitiveCount + 1];
Vector3 position = Vector3.Zero;
float angleInRadians = MathHelper.ToRadians(angleInDegrees);
for (int i = 0; i <= primitiveCount; i++)
{
if (orientationType == AlignmentPlaneType.XY)
{
position.X = (float)(radius * Math.Cos(i * angleInRadians));
position.Y = (float)(radius * Math.Sin(i * angleInRadians));
}
else if (orientationType == AlignmentPlaneType.XZ)
{
position.X = (float)(radius * Math.Cos(i * angleInRadians));
position.Z = (float)(radius * Math.Sin(i * angleInRadians));
}
else
{
position.Y = (float)(radius * Math.Cos(i * angleInRadians));
position.Z = (float)(radius * Math.Sin(i * angleInRadians));
}
vertices[i] = new VertexPositionColor(position, Color.White);
}
return(vertices);
}
//returns the vertices for a circle with a user-defined radius, sweep angle, and orientation
public static VertexPositionColor[] GetVerticesPositionColorCircle(int radius, int sweepAngleInDegrees, AlignmentPlaneType orientationType)
{
//sweep angle should also be >= 1 and a multiple of 360
//if angle is not a multiple of 360 the circle will not close - remember we are drawing with a LineStrip
if ((sweepAngleInDegrees < 1) || (360 % sweepAngleInDegrees != 0))
{
return(null);
}
//number of segments forming the circle (e.g. for sweepAngleInDegrees == 90 we have 4 segments)
int segmentCount = 360 / sweepAngleInDegrees;
//segment angle
float rads = MathHelper.ToRadians(sweepAngleInDegrees);
//we need one more vertex to close the circle (e.g. 4 + 1 vertices to draw four lines)
VertexPositionColor[] vertices = new VertexPositionColor[segmentCount + 1];
float a, b;
for (int i = 0; i < vertices.Length; i++)
{
//round the values so we dont end up with the two oordinate values very close to but not equals to 0
a = (float)(radius * Math.Round(Math.Cos(rads * i), ROUND_PRECISION_FLOAT));
b = (float)(radius * Math.Round(Math.Sin(rads * i), ROUND_PRECISION_FLOAT));
if (orientationType == AlignmentPlaneType.XY)
{
vertices[i] = new VertexPositionColor(new Vector3(a, b, 0), Color.White);
}
else if (orientationType == AlignmentPlaneType.XZ)
{
vertices[i] = new VertexPositionColor(new Vector3(a, 0, b), Color.White);
}
else
{
vertices[i] = new VertexPositionColor(new Vector3(0, a, b), Color.White);
}
}
return(vertices);
}
