Separated out flight gear scenery specifics into a separate Scenery
Generation section.
This commit is contained in:
curt
parent
1d390b6f66
commit
7260c176a9
3 changed files with 13 additions and 149 deletions
|
|
@ -150,95 +150,22 @@ coordinate systems. LaRCsim comes with code to convert back and forth
|
|||
between geodetic and geocentric coordinates. So, we only need to
|
||||
convert between geocentric and cartesian coordinates to complete the
|
||||
picture. Converting from geocentric to cartesian coordinates is done
|
||||
by using the following formula: \\
|
||||
$x = cos(lon_\mathit{geocentric}) * cos(lat_\mathit{geocentric}) *
|
||||
radius_\mathit{geocentric}$ \\
|
||||
$y = sin(lon_\mathit{geocentric}) * cos(lat_\mathit{geocentric}) *
|
||||
radius_\mathit{geocentric}$ \\
|
||||
$z = sin(lat_\mathit{geocentric}) * radius_\mathit{geocentric}$
|
||||
by using the following formula:
|
||||
|
||||
So far I haven't needed to convert from the cartesian coordinate
|
||||
system back into any of the polar representations so I haven't derived
|
||||
that part yet. However, it should be pretty straightforward.
|
||||
\noindent
|
||||
\[ x = cos(lon_\mathit{geocentric}) * cos(lat_\mathit{geocentric}) *
|
||||
radius_\mathit{geocentric} \]
|
||||
\[ y = sin(lon_\mathit{geocentric}) * cos(lat_\mathit{geocentric}) *
|
||||
radius_\mathit{geocentric} \]
|
||||
\[ z = sin(lat_\mathit{geocentric}) * radius_\mathit{geocentric} \]
|
||||
|
||||
Here is the formula to convert from cartesian coordinates back into
|
||||
geocentric coordinates:
|
||||
|
||||
\section{Scenery Representation}
|
||||
|
||||
This section is a work in progress. I am hashing out ideas as I
|
||||
write, so please feel free to send me your comments and suggestions.
|
||||
|
||||
\subsection{External Scenery Representation}
|
||||
|
||||
This section should deal with the external file format(s) that FG can
|
||||
use for input.
|
||||
|
||||
\subsection{Internal Scenery Representation}
|
||||
|
||||
This section describes how FG represents, manipulates, and
|
||||
transforms scenery internally.
|
||||
|
||||
Internal, all FG scenery is defined using the coordinate system shown
|
||||
in figure \ref{fig:coords}. This means that regardless of the
|
||||
external scenery representation, FG will convert all object to it's
|
||||
internal coordinate system when it loads the external file. Note,
|
||||
when a default external FG scenery representation is created, its
|
||||
representation should probably parallel the internal FG representation
|
||||
as close as possible. This way, most necessary conversions can then
|
||||
be done offline in advance.
|
||||
|
||||
\subsection{Scenery Partitioning}
|
||||
|
||||
For a first stab, scenery will be partitioned along longitude and
|
||||
latitude lines. This will form trapezium shaped chunks. I'd like to
|
||||
shoot for 10km x 10km chunks. So, as we move towards the poles, the
|
||||
width in degrees of these areas will have to increase. Figure
|
||||
\ref{fig:trap} shows an exaggerated scenery area.
|
||||
|
||||
\begin{figure}[hbt]
|
||||
\centerline{
|
||||
\psfig{file=trap.eps}
|
||||
}
|
||||
\caption{Scenery Partitioning Scheme}
|
||||
\label{fig:trap}
|
||||
\end{figure}
|
||||
|
||||
\subsection{Reference Points}
|
||||
|
||||
Each scenery area will have a reference point at the center of its
|
||||
area. This reference point (for purposes of avoiding floating point
|
||||
precision problems) defines the origin of a local coordinate system
|
||||
which is oriented the same as the global coordinate system. The only
|
||||
difference is the origin is translated from the center of the earth to
|
||||
the center of the individual areas. Figure \ref{fig:reference}
|
||||
demonstrates this.
|
||||
|
||||
\begin{figure}[hbt]
|
||||
\centerline{
|
||||
\psfig{file=ref.eps}
|
||||
}
|
||||
\caption{Reference Points and Translations}
|
||||
\label{fig:reference}
|
||||
\end{figure}
|
||||
|
||||
All the objects for a specific scenery area will be defined based on
|
||||
this local coordinate system. For each scenery area we define a
|
||||
vector $\vec{\mathbf{a}}$ which represents the distance from the
|
||||
center of the earth to the local coordinate system.
|
||||
|
||||
|
||||
\subsection{Putting the pieces of scenery together}
|
||||
|
||||
To render a scene, the scenery manager will need to load all the
|
||||
nearby areas. Also, we define a vector $\vec{\mathbf{v}}$ which
|
||||
represents the distance from the center of the earth to the current
|
||||
view point. Before rendering each scenery area we translate it by
|
||||
$\vec{\mathbf{a}} - \vec{\mathbf{v}}$. This moves all the current
|
||||
scenery areas near the origin, while maintaining the relative
|
||||
positions and orientations. All these transformations are inexpensive
|
||||
to calculate and can be done easily with standard OpenGL calls.
|
||||
|
||||
It is straightforward to calculate the proper view point and up vector
|
||||
so that the scenery will appear right side up when it is rendered.
|
||||
\noindent
|
||||
\[ lon = atan2( y, x ) \]
|
||||
\[ lat = \frac{\pi}{2} - atan2( \sqrt{x*x + y*y}, z ) \]
|
||||
\[ radius = \sqrt{x*x + y*y + z*z} \]
|
||||
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -1,47 +0,0 @@
|
|||
#FIG 3.2
|
||||
Landscape
|
||||
Center
|
||||
Inches
|
||||
Letter
|
||||
100.00
|
||||
Single
|
||||
0
|
||||
1200 2
|
||||
5 1 0 1 0 7 0 0 -1 0.000 0 1 0 0 6900.000 3304.688 5100 5700 6975 6300 8700 5700
|
||||
5 1 1 1 0 7 0 0 -1 4.000 0 0 0 0 6900.000 8100.000 5100 5700 6900 5100 8700 5700
|
||||
5 1 0 1 0 7 0 0 -1 4.000 0 0 0 0 6900.000 5175.000 5925 5100 6075 4650 6375 4350
|
||||
5 1 0 1 0 7 0 0 -1 4.000 0 0 0 0 8887.500 5062.500 6600 5325 6600 4800 6675 4425
|
||||
5 1 0 1 0 7 0 0 -1 4.000 0 1 0 0 6675.000 3975.000 5925 5100 6225 5250 6600 5325
|
||||
5 1 0 1 0 7 0 0 -1 4.000 0 1 0 0 6600.000 4087.500 6375 4350 6525 4425 6675 4425
|
||||
1 3 0 1 0 7 0 0 -1 0.000 1 0.0000 6900 5700 1802 1802 6900 5700 8700 5775
|
||||
2 1 0 1 0 7 0 0 -1 0.000 0 0 -1 1 0 2
|
||||
2 1 1.00 60.00 120.00
|
||||
6300 4800 6300 3600
|
||||
2 1 0 2 0 7 0 0 -1 0.000 0 0 -1 1 0 2
|
||||
2 1 2.00 120.00 240.00
|
||||
6900 5700 9300 5700
|
||||
2 1 0 2 0 7 0 0 -1 0.000 0 0 -1 1 0 2
|
||||
2 1 2.00 120.00 240.00
|
||||
6900 5700 7800 4800
|
||||
2 1 0 2 0 7 0 0 -1 0.000 0 0 -1 1 0 2
|
||||
2 1 2.00 120.00 240.00
|
||||
6900 5700 6900 3300
|
||||
2 1 0 1 0 7 0 0 -1 0.000 0 0 -1 1 0 2
|
||||
2 1 1.00 60.00 120.00
|
||||
6300 4800 7200 4800
|
||||
2 1 0 1 0 7 0 0 -1 0.000 0 0 -1 1 0 2
|
||||
2 1 1.00 60.00 120.00
|
||||
6300 4800 6750 4350
|
||||
2 1 0 1 0 7 0 0 -1 0.000 0 0 -1 1 0 2
|
||||
0 0 1.00 60.00 120.00
|
||||
6900 5700 6300 4800
|
||||
2 1 0 1 0 7 0 0 -1 0.000 0 0 -1 1 0 2
|
||||
0 0 1.00 60.00 120.00
|
||||
6075 4950 6300 4950
|
||||
4 0 0 0 0 0 14 0.0000 4 150 120 6825 3150 Z\001
|
||||
4 0 0 0 0 0 14 0.0000 4 150 135 7875 4800 Y\001
|
||||
4 0 0 0 0 0 14 0.0000 4 150 150 9450 5775 X\001
|
||||
4 0 0 0 0 0 12 0.0000 4 135 135 7275 4875 X\001
|
||||
4 0 0 0 0 0 12 0.0000 4 135 135 6675 4275 Y\001
|
||||
4 0 0 0 0 0 12 0.0000 4 135 120 6300 3525 Z\001
|
||||
4 0 0 0 0 0 12 0.0000 4 90 90 6150 5100 a\001
|
||||
|
|
@ -1,16 +0,0 @@
|
|||
#FIG 3.2
|
||||
Landscape
|
||||
Center
|
||||
Inches
|
||||
Letter
|
||||
100.00
|
||||
Single
|
||||
0
|
||||
1200 2
|
||||
5 1 0 1 0 7 0 0 -1 0.000 0 1 0 0 6900.000 3304.688 5100 5700 6975 6300 8700 5700
|
||||
5 1 1 1 0 7 0 0 -1 4.000 0 0 0 0 6900.000 8100.000 5100 5700 6900 5100 8700 5700
|
||||
5 1 0 1 0 7 0 0 -1 4.000 0 0 0 0 6900.000 5175.000 5925 5100 6075 4650 6375 4350
|
||||
5 1 0 1 0 7 0 0 -1 4.000 0 0 0 0 8887.500 5062.500 6600 5325 6600 4800 6675 4425
|
||||
5 1 0 1 0 7 0 0 -1 4.000 0 1 0 0 6675.000 3975.000 5925 5100 6225 5250 6600 5325
|
||||
5 1 0 1 0 7 0 0 -1 4.000 0 1 0 0 6600.000 4087.500 6375 4350 6525 4425 6675 4425
|
||||
1 3 0 1 0 7 0 0 -1 0.000 1 0.0000 6900 5700 1802 1802 6900 5700 8700 5775
|
||||
Loading…
Add table
Reference in a new issue