[Soc-2017-dev] vertex paint project - ply exporter

[Howard Trickey]

Darshan,

What are you working on now?

I looked a little more at the issue of alpha display after subdividing. I
am pretty sure now that the alphas are set properly -- if you remove all
but, say, the front (subdivided) face, the display looks OK. I tried
changing the glBlendfunc call to:
glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE,
GL_ONE_MINUS_SRC_ALPHA);
which seems more correct, but it didn't make any difference.

Maybe someone reading this with more experience with OpenGL and
alpha-blending has an idea?  I wonder if somehow we have to turn on drawing
the elements in proper z-sorted order?


On Tue, Jul 18, 2017 at 9:48 AM Howard Trickey <howard.trickey at gmail.com>
wrote:

> Darshan,
>
> I made a little python function to dump the vertex (loop) colors on the
> console.  You may find this useful.  If you put this in, say, the
> release/scripts/startup folder then you can use the <Space>-menu to search
> for 'Dump Vertex Colors'.  To see which faces and vertices correspond to
> which dumped colors, you can start blender with --debug and then enable the
> 'indices' visualization box in the right-hand panel of view3d (when in Edit
> mode) to see the indices of the currently selected elements.
>
> I think there may be a problem with the ply exporter, discovered by using
> this. I made a simple plane quad and put different colors and alphas on
> each, and then the ply exporter seemed to have an off-by-one error in
> lining up colors with vertices. But I looked briefly at the code and didn't
> see what was wrong.
>
> I also checked the interpolation of alpha's when subdividing and agree
> with you that it seems to be doing approximately the right thing, so the
> problem is somehow in the visualization code.
>
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