Hi again. Ok, things are getting clearer now. I studied everything and came now to the tesselator part.
AFAIK, curves and lines are loaded into a list of "edges" which then are either passed as "line strips" to the renderer (in the case of an outline) or mangled through the tesselator if it is a filled shape. BTW, straight lines seem to be converted to curves where the control point equals the new anchor point (resulting a straight line on screen). That explains why simple straight lines are drawn in pieces of different length. This could be optimized, I'd say... Back to my question: The outline mesh is passed to the "tesselator", which seems to generate a list of trapezoids that together form the correct fill for the shape, correct? These trapezoids have parallel upper and lower sides, and probably they perfectly horizontal on the screen. Ok, these trapezoids are then split to two triangles via the "tri_stripper". I guess this is to support accelerated hardware? Anyway, in the end we probably have a bunch of triangles that form the shape (and are passed to the backend). Now, we would like to bypass the tesselator completely and let the backend draw the original shape itself (based on straight lines is ok). The reason is that these triangles (the shape) look awful when rendered through AGG. This may be because of the anti-aliasing or because AGG does some intersection computing. Anyway, one can clearly recognize those triangles when a simple rectangle should be displayed. Anyway, I'd like to learn more about the tesselator because it's the missing piece in my Gnash puzzle. I hope someone can answer any of these questions: - What's the true story behind the tesselator and the trapezoids? I admit I don't know anything about filling algorithms theory. - Are the triangles really just two pieces of the trapezoids? I ask because the "tri_stripper" is implemented rather complicated for such a simple task. Apparently the order of the triangles follow some logic? - What do the arguments passed to add_trapezoid() exactly mean? - Is all this tesselator/trapezoid/triangle stuff used *only* for rendering or has it an additional uses, for example collision detection? With other words: Would it be safe to disable it altogether? Looking forward for any hint, Udo _______________________________________________ Gnash-dev mailing list [email protected] http://lists.gnu.org/mailman/listinfo/gnash-dev
