Rendering spheres (or points) in a particle system

Question

I am using the Three.JS library to display a point cloud in a web brower. The point cloud is generated once at start up and no further points are added or removed. But it do

Answer 1

When comparing my code to http://threejs.org/examples/#webgl_custom_attributes_particles3 I saw the only difference was:

vec4 outColor = texture2D( texture, gl_PointCoord );
if ( outColor.a < 0.5 ) discard;
gl_FragColor = outColor;

Added to the fragment shader, fixed this problem for me.

It wasn't z fighting because randomly, some corners would overlap distant particles. material.alphaTest = 0.5 didn't work and turning off depth writes/tests messed up the viewing order.