Yay, it works! Drawing broad lines the pygamedraw way

The the basic shape algorithms are mostly implemented and I get more and more to the parts of implementing new features and improving stuff. Today I worked one the Pen.line() method or more specifically the drawing of broad poly-lines through more than two points.

First, lets have a look how the current implementation does it:

Well, that’s just a multiple call of pygame.draw.line() which is also badly implemented as it simply adds half of the width on both sides to either the x or y values of the endpoints (and thus different angles result in different line widths). This is just ugly and nearly unusable.

So I had to fix that and do a bit more than calling Pen.line(surf, point1, point2). But what? There are quite a few ways how to draw the corners and so I added the next attribute to the Pen class, called line_style.

Currently there are 4 different line styles (and no more planned because I cannot think of any further (useful) style(s), but if you do, please tell me and I may think about it): DENTED_VERT, SHARP_VERT, FLAT_VERT and ROUND_VERT.

First of all, I did some studies and tests and thought about lines and how to draw and connect them to nice-looking polylines:

I started with a simple row of single line elements.

Then reduced it to pure data.

Some more tests and a first, ugly hacked version ensued. Then I rewrote it and did a cleaner implementation using an own Vert class to hold the data and do some calculations.

At the end, it looks like this:

Pen.line_style = DENTED_VERT

Pen.line_style = SHARP_VERT (yes, I know there is still a small pixel bug)

Pen.line_style = FLAT_VERT

Pen.line_style = ROUND_VERT

I also added a first style for line endings (more styles will come later):

Pen.line_style = ROUND_VERT Pen.line_start = ROUND_ENDING Pen.line_ending = ROUND_ENDING

Yay, that’s a lot better and more flexible than the current pygame/sdl implementation and thas is what this whole GSoC project is all about! 🙂