Update README.md

gcodeextractor/README.md

@@ -34,6 +34,22 @@ Enter the parameters in the proper boxes:
 Once all parameters are entered, you can click on the **execute program** button.
 If everything is good, you should read **SUCCESS** on the bottom of the UI, else and error code should appear.
 
+### Algorithms
+
+To convert a pcb image into a gcode, we first find where the tool will have to travel, in order to create the pcb. This is done in the path.py file. The pcb image is a matrix in which the connections are represented by 1's and the empty space by 0's, we use 2's to represent the tool's path. path.py has 3 functions, the first one (scanHorizontal) adds 2's on the left or the right of 1's if they are the beginning or end of a line, it adds a column of 2's the size of the tool's diameter at a tool's radius away from the 1. the second function (scanVertical) is similar but instead of looking and adding on left side or right side, it does on up side or down side. The third function (twoRemoving) removes 2's where there shouldn't be, by looking near the 1's and removing 2's that would make the tool touch the 1.
+
+We then create a sequence of coordinates for the tool to follow to cover all the path we just created. This is done in gcodeCreator.py. We create a sequence of straight lines only, circles or diagonals are a sum of straight lines. The sequence is created by the function *create sequence* that goes through all pixels in the image to find a 2 where the tool will start working. It starts the sequence by a set of coordinates (-1,-1), which means it is starting a new path, and a set of coordinates where the 2 is. Then it uses the function *findDirection* to seek for 2's nearby to find a direction where to travel. It will continue in this direction with the function *findEndOfLine* until it hits the last 2 of the line, adding it's coordinates to the sequence, and then seek for another direction until it can't find any 2's. All the 2's covered by the sequence are changed by 3's so the algorithm never cover the same 2 twice. Once it comes to the end of a path, the algorithm will continue looking for 2's where to start paths from until it has look through all the pixels of the image.
+
+The last file is GcodeBuilder.py, it transforms the sequence of point into a standard gcode file. It does so by changing the coordinates in pixels, into coordinates in mm according to the dimensions of the pcb. If the coordinates are (-1,-1), this means the sequence has finished a path and the tool should not be working until it gets to the next coordinates. The gcode file also starts with a header and ends with a footer to add some configs and a homing.
+
+### tests
+
+For path.py's function, we tested the three functions with small matrix of 0's and 1's and wrote the expected results manually to compare if the functions returned what we expected. we also tested if the algorithms would still work if it had to write or read out of bound of the image, which is verified in the algorithms. 
+
+The tests for GcodeCreator.py where made in a similar way, with small matrices of 0's and 2's and an expected sequence of coordinates to compare. We also tested if the algorithm had to read out of bound of the image.
+
+For GcodeBuilder.py, we created some coordinates sequences and a similar but simpler algorithm that would give us the resulting gcode. We compared the function's results with the simpler algorithm's results to see if they were the same. We also tested for different pixel sizes.
+
 ## Authors
 
 **Ian Lalonde**