Ah, got it, it was a matter of sending variables without the "get" method... so this worked: spheretoscreen(hotspot[trackinghtsp_1].ath, hotspot[trackinghtsp_1].atv, hotspotPosX, hotspotPosY);

Hello there, I am trying to do something similar to this, although I do understand the mathematical limitations, so I only need to know when hotspots are outside of the FOV but still in the projection plane, hence "close" to being displayed. Although I think there's another problem... I am doing what the original poster was: spheretoscreen(get(hotspot[trackinghtsp_1].ath), get(hotspot[trackinghtsp_1].atv), hotspotPosX, hotspotPosY); and the values for hotspotPosX and hotspotPosY always refer to ...