What is Picture to People ?
"Picture to People" (P2P) is a huge Computer Graphics project. It was started to create new softwares able to make 2D drawing, 3D rendering, vexel drawing, text effects, photo effects, image filtering and other complex Computer Graphics operations. It has been made from scratch, including its low level Computer Graphics libraries like Maccala. Nowadays, most final features produced for this project are released as free online tools available from its official website. This blog talks about Computer Graphics, mainly concerning Picture to People development.
Friday, May 6, 2011
Maccala improvement: Polygon filling modes
Nowadays I have a very comprehensive, professional, powerful and robust library for 2D drawing, font rendering and vector based effects, but I knew it had a point to be solved: the polygon filling modes. Since its first days, the library had only the alternative filling mode. I always knew about this weakness, but I have let it behind, since its only mode always was enough to my needs until now.
Currently I'm developing a new sub-library especially to make typography effects. At this point, the lack of another filling mode became a barrier to creation of my new effects.
I'm (finally) implementing the winding filling mode in Maccala. Since it's more complex by nature, I'm taking a big care about performance, so I can draw using any filling mode with no (or very few) performance penalty.
If you don't know what I'm talking about, let's put it simple: the winding mode can be imperative when filling some kinds of polygons that have self-intersection. This kind of polygon is very common, mainly when you make some operations like polyline thickness widening.
Below there is a simple example. First I show a self-intersected polygon. Second I show the same polygon filled using the alternative mode. As you can see, a colateral effect of this technique is that, in this case, the polygon is not completely filled. Finally I show the winding mode applied to our polygon. It has the behavior we usually want in this situation: the polygon is totally filled.