OpenGL ES Android: why does my point cloud fade during rotate

I load an STL mesh, draw it correctly (using GL_TRIANGLES), rotate nicely, change colour, the lights stay in position while the mesh moves, everything is开发者_Go百科 great. Then I switch off the triangles and display just the vertices (using GL_POINTS), now when I rotate (and even when I display the triangles and the vertices together) the points seem to fade out as I rotate - as if they are lit from only one side.

Does this ring any bells with anyone?

Thanks for any help.

Baz

It maybe just a perception artefact. If you still got lighting on, the points are of course lit like the triangle vertices (depending on their normals), meaning they actually have an orientation, even if this is not intuitive for points. So they may get darker or brighter when rotating them into/away from the light. It's just that this change seems more evident, because you don't have the other surface points to fill the gaps and compensate for the dimming. Try disabling lighting and they should keep their color when rotating.