Are you trying to trace from the camera to a position 1000 quants away in the same direction that it is pointing?

If so, you could try something like this:

var vecTgt[3];

vec_set(target_pos.x, camera.x);
vec_for_angle(vecTgt, camera.pan );
vec_scale(vecTgt, 1000);
vec_add(target_pos.x, vecTgt);