Create a sketch drawing from x,y coordinates

We have an application that contains a table of sequential x,y coordinates that represent measurements. A screen is attached which has a sample of what the table looks like. Each object is written out to the database and from each x,y coordinate to the next x,y cordinate a straight line needs to be drawn. Some objects will be three sided triangles and others will be 4 sided rectangles. The combined objects represent the top down view of a roof and its various planes. I am attaching an example of the end result. The job is to draw out the object to be viewed on the screen and then saved to a pdf or printed out. You will notice that some objects have 3 rows of points and some have 4 rows of points. The last connecting point of any object will be the last row of a series connecting back to the 1st row of a series. There is a little more to this, but if you can understand the job based upon this description then I can explain the rest of this which is merely knowing which records and areas need to be included. This has to be done in php and the application uses a mysql database.