Oh you mean the camera view is in some way scaled down ? So if rendering at say 1/1000th scale, then the dimensions of the camera view is also scaled down to 1/1000th ? That reduces the view frustum depth to 1/1000th so that would bring the planes much closer.
But then this view has to be scaled up again to match the back buffer width and height, or at least the same camera view dimensions as the ones with which the vessel in orbit is rendered.
---------- Post added at 09:08 PM ---------- Previous post was at 09:02 PM ----------
Ok I got a good bunch of articles on this :
http://www.gamasutra.com/view/authors/322755/Sean_O'Neil.php
So he sets the far plane at some constant, sufficient to ensure z-buffer precision, then scales down everything, size and distance, exponentially. So this preserves the z-order and everything fits inside the squeezed view frustum too.
Still digging into how to match this down scaled stuff up with the scale in which the
normal objects like vessels etc are rendered. Just scale the planet's
rendered image to match the back buffer size ? Or maybe I am totally wrong here and there is no need to match it up at all as the camera view is rendered to the entire viewport and is automatically
stretched. As in, the view through the camera would not look any different even if the actual scale at which everything was rendered was lower.
---------- Post added 28-12-13 at 12:23 AM ---------- Previous post was 27-12-13 at 09:08 PM ----------
ok, I am beginning to understand this separate pass rendering more clearly now after reading :
http://www.gamasutra.com/view/feature/131393/a_realtime_procedural_universe_.php?page=3
multiple times
The maximum allowable ratio of near to far plane distance seems to be 1:10000. So the earth being about 12,742,000 meters wide, it can be scaled down by 1/2000 to say a 6371 meter sphere. All rendering and texturing would be done at this scale. Then the rendered image is simply rendered as a textured quad into the backbuffer
If other bodies like the Moon is visible, it is scaled down and brought closer by the same distance.
But scaling down the Moon's distance by 1/2000 brings it to 192,200 meters. Thats still much farther than the far plane. Do we then scale down
only the Moon further at perhaps 1/10,000 ? But still render the Earth at 1/2000 ?
When both images are composited into the final image, wont the difference in size be noticeable ?