[PD] Gem line2D max line width

Claude Heiland-Allen claude at mathr.co.uk
Sun Apr 26 01:25:55 CEST 2015

On 25/04/15 22:27, Peter P. wrote:
> In Gem I would like to make a 2D Bezier curve with the [line2D] object

I can't find any reference to [line2D] in my fresh GEM clone.  Do you 
mean [curve]?

> and give it a width bigger than 250, drawing it as "linestrip". But the
> line does not get thicker.

250 is quite high.

> Is there a limit to it,


> if so why,

Defined by the underlying OpenGL implementation:

Not sure if GEM exposes the query methods.

> and how could I work around this?

Draw wide lines as triangle strips - maybe look at [curve3d] for that?

It's possible in OpenGL 3.2 to use a geometry shader to convert line 
strips to triangle strips, using input layout lines_adjacency so that 
you can take into account the corners.  But that requires that you draw 
with GL_LINE_STRIP_ADJACENCY, which isn't supported by GemShape, and the 
polynomial evaluators used in [curve] were removed before OpenGL version 


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