3D view
There was a misusage of the `outcol` and `texcol` params. The actual
formula should have been:
incol = facm * outcol + fact * ((one - outcol) * texcol * outcol +
outcol * scr);
To make sure the result is consistent with material mode, reuse the
material blend function (mix_soft), similarly to what most other texture
blend modes do.