I'm working on a little AR app, and it would be helpfull if there was a way to make billboard sprites not scale with distance.
That is, if they are far away they are the same size as near.
I figured theres two ways of doing this, and I wondered if anyone could give feedback on what seems the best and what sort of maths would be required;
1. Each time the camera moves scale all the billboard sprites to compansate. This would mean mesuring their distance to then camera [insert formular] and scaleing based on that.
2. Drawing the sprites directly to the screen not using the 3D scene at all - obviously this takes care of the scaleing easily, but raise's issues such as drawing order and positioning.
I'm guessing number 1 will be more flexible, and 2 would be more efficiant in terms of cpu.
Number 1 would also let me scale by other methods too if I wished - like getting slightly smaller with distance rather then realisticly exponetialy smaller.
The camera in my app shouldn't be moving too much - walking pace in a city with gps updates probably means only once every few seconds at most.
So..and ideas on the direction I should take?