Freestyle integration into Blender

April 30, 2008

Freestyle: controller component reviewed

Filed under: Update — The dev team @ 4:32 PM

I have just finished reviewing the app/ folder. I think that I get a rough idea of how things work in code, reproducing the basic steps from initializing the controller, opening a file, setting a style, computing the view map and rendering the strokes. From what I understand, I need to see how the Canvas class works in more detail, so I will do that tomorrow. I am keeping in mind that the first phase will make Freestyle independent from Qt, so all dependencies have to be looked at in detail.

Stéphane, I have surely overlooked but I haven’t been able to see the interactive shader window or the “Compute Steerable Viewmap” in Freestyle. Are they used in the Mac OS X version ? What are steerable view-maps ?

1 Comment »

  1. Q: Where is the interactive shader window?
    A: It is the text window to edit a shader. It can be opened from the list of shaders displayed in the “Style modeler window” by double-clicking on a shader title.

    Q: What is a Steerable ViewMap?
    A: Mostly a bad name :-) It actually designates a series of 4 Gaussian image pyramids that encodes the density of the visible lines of the View Map in 4 base directions (-45 degrees, 0 degree, 45 degree, 90 degrees) and an extra image pyramid that encodes the all-direction density. The technique is inspired form the Steerable filters, hence the name. These maps are useful to successfully perform abstraction (through line omission) of structured views (eg grids, houses, …) that exhibit many parallel lines. This set of density maps together is called the “a priori density”, because it encodes the a priori knowledge of the drawing before the strokes are actually drawn.

    Q: Where is the “Compute Steerable Viewmap”?
    A: It is a flag that can be checked/unchecked in the Options window under the “Miscellaneous” tab. If it is checked, the “a priori density maps” are computed along with the ViewMap (on a call to “Compute ViewMap”). If there is no intent to perform abstraction in the shaders, then these maps don’t need to be computed.

    Comment by stephane — May 1, 2008 @ 9:26 PM

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