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Add comments that explain the coordinate systems and transformations in SunDisplay. Ref #310

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This commit is contained in:
John M. Penn 2016-09-14 17:16:42 -05:00
parent 2aa0287fb9
commit f186b91afc
1 changed files with 71 additions and 34 deletions
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105
trick_sims/SIM_sun/models/Graphics/src/sundisplay/SunDisplay.java
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@ -29,27 +29,34 @@ import javax.swing.JPanel;
*/
class NWUPoint {
double n;
double w;
double u;
// NWUPoint is a point in North-West-Up coordinates.
// We use unit vectors in this coordinate system to point to locations on the
// celestial sphere.
double n; // Positive to the north.
double w; // Positive to the west.
double u; // Positive up.
public NWUPoint (double N, double W, double U) {
n = N;
w = W;
u = U;
}
public NWUPoint (double az, double el) {
n = Math.cos(az) * Math.cos(el);
w = -Math.sin(az) * Math.cos(el);
u = Math.sin(el);
// In the the following constructor, az and el are the azimuth and elevation
// of an object on the celestial sphere. az is measured from north, and is
// positive clock-wise. el is measured from the horizon, and is positive up.
public NWUPoint (double heading, double elevation) {
// Create a NWUPoint from compass heading, and elevation.
// Note that compass heading is positive clockwise.
n = Math.cos(heading) * Math.cos(elevation);
w = -Math.sin(heading) * Math.cos(elevation);
u = Math.sin(elevation);
}
}
class CameraPoint {
double x;
double y;
double z;
// CameraPoint is a point in Camera coordinates.
double x; // Out along the camera line of sight.
double y; // Positive to the left.
double z; // Positive up.
public CameraPoint (double X, double Y, double Z) {
x = X;
@ -57,25 +64,56 @@ class CameraPoint {
z = Z;
}
public CameraPoint (NWUPoint nwu, double elevation, double azimuth) {
x = -nwu.w * Math.cos(azimuth) + nwu.n * -Math.sin(azimuth);
y = -nwu.w * Math.cos(elevation) * Math.sin(azimuth) + nwu.n * Math.cos(azimuth) * Math.cos(elevation) + nwu.u * -Math.sin(elevation);
z = -nwu.w * Math.sin(azimuth) * Math.sin(elevation) + nwu.n * Math.cos(azimuth) * Math.sin(elevation) + nwu.u * Math.cos(elevation);
public CameraPoint (NWUPoint nwu, double CameraElevation, double CameraHeading) {
// Create a CameraPoint from a NWUPoint.
// CameraHeading - Compass heading of the camera.
// CameraElevation - Elevation of the camera above the horizon.
// NOTE that NWU is a right-hand coordinate system,
// and that compass heading (like on a ship or airplane) is
// in the opposite direction of a positive z-axis rotation.
// Therefore, our z-axis rotation is the negative of CameraHeading.
// CameraElevation is a positive rotation.
double yrot = CameraElevation;
double zrot = -CameraHeading;
// |camera_x| | cos(yrot) 0 -sin(yrot) | | cos(zrot) sin(zrot) 0 | |n|
// |camera_y| = | 0 1 0 | * |-sin(zrot) cos(zrot) 0 | * |w|
// |camera_z| | sin(yrot) 0 cos(yrot) | | 0 0 1 | |u|
//
// | cos(zrot)* cos(yrot) cos(yrot)* sin(zrot) -sin(yrot) | |n|
// = | -sin(zrot) cos(zrot) 0 | * |w|
// | cos(zrot)* sin(yrot) sin(zrot)* sin(yrot) cos(yrot) | |u|
x = nwu.n * Math.cos(zrot) * Math.cos(yrot) + nwu.w * Math.cos(yrot) * Math.sin(zrot) + nwu.u * -Math.sin(yrot);
y = nwu.n * -Math.sin(zrot) + nwu.w * Math.cos(zrot);
z = nwu.n * Math.cos(zrot) * Math.sin(yrot) + nwu.w * Math.sin(zrot) * Math.sin(yrot) + nwu.u * Math.cos(yrot);
}
}
class ViewPoint {
int x;
int y;
// Viewpoint is a point in JPanel-Graphics2D coordinates. The origin of the
// JPanel-Graphics2D coordinates is the upper left hand corner of the JPanel.
int x; // Positive to the right.
int y; // Positive down.
public ViewPoint (int X, int Y) {
x = X;
y = Y;
}
public ViewPoint (CameraPoint cp, double d ) {
x = (int)(d/2 * (1.0 + cp.x));
y = (int)(d/2 * (1.0 - cp.z));
public ViewPoint (CameraPoint cp, double origin_x, double origin_y, double scale) {
// Transform point in Camera Coordinates to ViewPoint (Jpanel-Graphics2D) Coordinates
//
// |camera_x|
// |view_x| = |origin_x| + scale * | 0 -1 0| * |camera_y|
// |view_y| = |origin_y| | 0 0 -1| |camera_z|
x = (int)(origin_x + scale * -cp.y);
y = (int)(origin_y + scale * -cp.z);
}
}
@ -109,7 +147,6 @@ class SkyMap extends JPanel {
Color groundColor;
Color textColor;
public SkyMap() {
sun_azimuth = 0.0;
sun_elevation = 0.0;
@ -167,14 +204,14 @@ class SkyMap extends JPanel {
double sun_az_rad = Math.toRadians(sun_azimuth);
double sun_el_rad = Math.toRadians(sun_elevation);
ViewPoint centerPoint = new ViewPoint( new CameraPoint( 0.0, 0.0, 0.0 ), d );
ViewPoint centerPoint = new ViewPoint( new CameraPoint( 0.0, 0.0, 0.0 ), d/2, d/2, d/2 );
ViewPoint p1 = new ViewPoint( new CameraPoint( new NWUPoint( sun_az_rad, 0.0), obs_el_rad, obs_az_rad), d );
ViewPoint p1 = new ViewPoint( new CameraPoint( new NWUPoint( sun_az_rad, 0.0), obs_el_rad, obs_az_rad), d/2, d/2, d/2 );
ViewPoint p2 = new ViewPoint( new CameraPoint( new NWUPoint( Math.toRadians( 0.0), 0.0), obs_el_rad, obs_az_rad), d );
ViewPoint p3 = new ViewPoint( new CameraPoint( new NWUPoint( Math.toRadians(180.0), 0.0), obs_el_rad, obs_az_rad), d );
ViewPoint p4 = new ViewPoint( new CameraPoint( new NWUPoint( Math.toRadians( 90.0), 0.0), obs_el_rad, obs_az_rad), d );
ViewPoint p5 = new ViewPoint( new CameraPoint( new NWUPoint( Math.toRadians(270.0), 0.0), obs_el_rad, obs_az_rad), d );
ViewPoint p2 = new ViewPoint( new CameraPoint( new NWUPoint( Math.toRadians( 0.0), 0.0), obs_el_rad, obs_az_rad), d/2, d/2, d/2 );
ViewPoint p3 = new ViewPoint( new CameraPoint( new NWUPoint( Math.toRadians(180.0), 0.0), obs_el_rad, obs_az_rad), d/2, d/2, d/2 );
ViewPoint p4 = new ViewPoint( new CameraPoint( new NWUPoint( Math.toRadians( 90.0), 0.0), obs_el_rad, obs_az_rad), d/2, d/2, d/2 );
ViewPoint p5 = new ViewPoint( new CameraPoint( new NWUPoint( Math.toRadians(270.0), 0.0), obs_el_rad, obs_az_rad), d/2, d/2, d/2 );
g2d.setPaint(Color.WHITE);
g2d.drawString("North", p2.x, p2.y);
@ -190,7 +227,7 @@ class SkyMap extends JPanel {
g2d.drawLine(centerPoint.x, centerPoint.y, p1.x, p1.y);
// Draw the Sun.
ViewPoint sun_point = new ViewPoint( new CameraPoint( new NWUPoint( sun_az_rad, sun_el_rad), obs_el_rad, obs_az_rad), d );
ViewPoint sun_point = new ViewPoint( new CameraPoint( new NWUPoint( sun_az_rad, sun_el_rad), obs_el_rad, obs_az_rad), d/2, d/2, d/2 );
g2d.setPaint(sunColor);
drawCenteredCircle(g2d, sun_point.x, sun_point.y, 20);
@ -258,7 +295,7 @@ public class SunDisplay extends JFrame implements ActionListener {
JButton b3 = new JButton("\u25ce");
b3.addActionListener(this);
b3.setActionCommand("reset");
b3.setToolTipText("Reset");
b3.setToolTipText("Camera Reset");
buttonPane.add(b3);
JButton b4 = new JButton("\u25b2");