mrdoob/three.js — pull request #2651 by jfeldste (2012-11-19 19:51:34+00:00)
Title: Update examples/webgl_custom_attributes_particles3.html

The result for attributes.size.value[i] can be negative which in turn makes gl_PointSize negative. As an example if Math.sin(...) returns -1 then you'll get -6 as a result.

The specification specifically states:"If the value written to gl_PointSize is less than or equal to zero, results are undefined". In fact it is causing such a problem on our platform.