In my previous post 'Drawing a circle in SQL Server (almost)' I showed how to plot 360 points to draw a circle. {Well} It looked like a circle, but to SQL Server, it was just a series of points.
We can use a LineString to draw a shape, but the most appropriate type is the Polygon.
The polygon is a closed [at least 3 sided] shape, i.e. the first point is the same as the same point. If it’s not, SQL will throw an exception. SQL Server will also throw an exception if you attempt to create a polygon with just two sides..
1: -- Drawing a polygon
2: declare @Sides float = 3
3: declare @count int = 0
4: declare @size int = 10
5: declare @firstpoint varchar(400)
6: 7: declare @sql varchar(8000);
8: 9: 10: set @sql = 'POLYGON(('
11: 12: while(@count < @Sides)
13: begin
14: 15: set @sql = @sql + cast(SIN(RADIANS((CAST(@count AS FLOAT)
16: /CAST(@Sides AS FLOAT))
17: * 360)) * @size as varchar)
18: + ' ' +
19: cast(COS(RADIANS((CAST(@count AS FLOAT)
20: /CAST(@Sides AS FLOAT))
21: * 360)) * @size as varchar) + ','
22: 23: if @count = 0
24: set @firstpoint = cast(SIN(RADIANS((CAST(@count AS FLOAT)
25: /CAST(@Sides AS FLOAT))
26: * 360)) * @size as varchar)
27: + ' ' +
28: cast(COS(RADIANS((CAST(@count AS FLOAT)
29: /CAST(@Sides AS FLOAT))
30: * 360)) * @size as varchar)
31: 32: set @count = @count + 1
33: 34: end
35: 36: set @sql = @sql + @firstpoint + '))'
37: 38: print @sql
39: DECLARE @g geometry;
40: SET @g = geometry::STGeomFromText(@sql, 0);
41: select @g
42: Simply change
1: declare @Sides float = 3
to be how ever many sides you need. Simple.
Here are a few examples.
All scripts can be found on my SkyDrive using the link below.
