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flightgear/Astro/star.cxx
curt 33726fc21b Changes contributed by Durk Talsma: 
Here's a few changes I made to fg-0.58 this weekend. Included are the
following features:
- Sun and moon have a halo
- The moon has a light vector, moon_angle, etc. etc. so that we can have
  some moonlight during the night.
- Lot's of small changes tweakes, including some stuff Norman Vine sent
  me earlier.
1999-03-22 02:08:05 +00:00

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/**************************************************************************
* star.cxx
* Written by Durk Talsma. Originally started October 1997, for distribution
* with the FlightGear project. Version 2 was written in August and
* September 1998. This code is based upon algorithms and data kindly
* provided by Mr. Paul Schlyter. (pausch@saaf.se).
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#ifdef __BORLANDC__
# define exception c_exception
#endif
#include <math.h>
#include <Time/sunpos.hxx>
#include <Debug/logstream.hxx>
#include <Time/light.hxx>
#include "star.hxx"
/*************************************************************************
* Star::Star(fgTIME *t)
* Public constructor for class Star
* Argument: The current time.
* the hard coded orbital elements our sun are passed to
* CelestialBody::CelestialBody();
* note that the word sun is avoided, in order to prevent some compilation
* problems on sun systems
************************************************************************/
Star::Star(fgTIME *t) :
CelestialBody (0.000000, 0.0000000000,
0.0000, 0.00000,
282.9404, 4.7093500E-5,
1.0000000, 0.000000,
0.016709, -1.151E-9,
356.0470, 0.98560025850, t)
{
FG_LOG( FG_GENERAL, FG_INFO, "Initializing Sun Texture");
#ifdef GL_VERSION_1_1
xglGenTextures(1, &sun_texid);
xglBindTexture(GL_TEXTURE_2D, sun_texid);
#elif GL_EXT_texture_object
xglGenTexturesEXT(1, &sun_texid);
xglBindTextureEXT(GL_TEXTURE_2D, sun_texid);
#else
# error port me
#endif
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
setTexture();
glTexImage2D( GL_TEXTURE_2D,
0,
GL_RGBA,
256, 256,
0,
GL_RGBA, GL_UNSIGNED_BYTE,
sun_texbuf);
SunObject = gluNewQuadric();
if(SunObject == NULL)
{
printf("gluNewQuadric(SunObject) failed !\n");
exit(0);
}
//SunList = 0;
distance = 0.0;
}
Star::~Star()
{
//delete SunObject;
delete [] sun_texbuf;
}
static int texWidth = 256; /* 64x64 is plenty */
void Star::setTexture()
{
int texSize;
//void *textureBuf;
GLubyte *p;
int i,j;
double radius;
texSize = texWidth*texWidth;
sun_texbuf = new GLubyte[texSize*4];
if (!sun_texbuf)
return; // Ugly!
p = sun_texbuf;
radius = (double)(texWidth / 2);
for (i=0; i < texWidth; i++) {
for (j=0; j < texWidth; j++) {
double x, y, d;
x = fabs((double)(i - (texWidth / 2)));
y = fabs((double)(j - (texWidth / 2)));
d = sqrt((x * x) + (y * y));
if (d < radius)
{
double t = 1.0 - (d / radius); // t is 1.0 at center, 0.0 at edge */
// inverse square looks nice
*p = (int)((double)0xff * (t * t));
*(p+1) = (int)((double) 0xff * (t*t));
*(p+2) = (int)((double) 0xff * (t*t));
*(p+3) = (int)((double) 0xff * (t*t));
}
else
{
*p = 0x00;
*(p+1) = 0x00;
*(p+2) = 0x00;
*(p+3) = 0x00;
}
p += 4;
}
}
//gluBuild2DMipmaps(GL_TEXTURE_2D, 1, texWidth, texWidth,
// GL_LUMINANCE,
// GL_UNSIGNED_BYTE, textureBuf);
//free(textureBuf);
}
/*************************************************************************
* void Jupiter::updatePosition(fgTIME *t, Star *ourSun)
*
* calculates the current position of our sun.
*************************************************************************/
void Star::updatePosition(fgTIME *t)
{
double
actTime, eccAnom,
xv, yv, v, r,
xe, ye, ze, ecl;
updateOrbElements(t);
actTime = fgCalcActTime(t);
ecl = DEG_TO_RAD * (23.4393 - 3.563E-7 * actTime); // Angle in Radians
eccAnom = fgCalcEccAnom(M, e); // Calculate the eccentric Anomaly (also known as solving Kepler's equation)
xv = cos(eccAnom) - e;
yv = sqrt (1.0 - e*e) * sin(eccAnom);
v = atan2 (yv, xv); // the sun's true anomaly
distance = r = sqrt (xv*xv + yv*yv); // and its distance
lonEcl = v + w; // the sun's true longitude
latEcl = 0;
// convert the sun's true longitude to ecliptic rectangular
// geocentric coordinates (xs, ys)
xs = r * cos (lonEcl);
ys = r * sin (lonEcl);
// convert ecliptic coordinates to equatorial rectangular
// geocentric coordinates
xe = xs;
ye = ys * cos (ecl);
ze = ys * sin (ecl);
// And finally, calculate right ascension and declination
rightAscension = atan2 (ye, xe);
declination = atan2 (ze, sqrt (xe*xe + ye*ye));
}
void Star::newImage(void)
{
/*static float stars[3];
stars[0] = 0.0;
stars[1] = 0.0;
stars[2] = 1.0;*/
fgLIGHT *l = &cur_light_params;
float sun_angle = l->sun_angle;
if( sun_angle*RAD_TO_DEG < 100 ) { // else no need to draw sun
double x_2, x_4, x_8, x_10;
GLfloat ambient;
GLfloat amb[4];
int sun_size = 750;
// daily variation sun gets larger near horizon
/*if(sun_angle*RAD_TO_DEG > 84.0 && sun_angle*RAD_TO_DEG < 95)
{
double sun_grow = 9*fabs(94-sun_angle*RAD_TO_DEG);
sun_size = (int)(sun_size + sun_size * cos(sun_grow*DEG_TO_RAD));
}*/
x_2 = sun_angle * sun_angle;
x_4 = x_2 * x_2;
x_8 = x_4 * x_4;
x_10 = x_8 * x_2;
ambient = (float)(0.4 * pow (1.1, - x_10 / 30.0));
if (ambient < 0.3) ambient = 0.3;
if (ambient > 1.0) ambient = 1.0;
amb[0] = ((ambient * 6.0) - 1.0); // minimum value = 0.8
amb[1] = ((ambient * 11.0) - 3.0); // minimum value = 0.3
amb[2] = ((ambient * 12.0) - 3.6); // minimum value = 0.0
amb[3] = 1.00;
if (amb[0] > 1.0) amb[0] = 1.0;
if (amb[1] > 1.0) amb[1] = 1.0;
if (amb[2] > 1.0) amb[2] = 1.0;
xglColor3fv(amb);
glPushMatrix();
{
xglRotatef(((RAD_TO_DEG * rightAscension)- 90.0), 0.0, 0.0, 1.0);
xglRotatef((RAD_TO_DEG * declination), 1.0, 0.0, 0.0);
xglTranslatef(0,60000,0);
glEnable(GL_TEXTURE_2D); // TEXTURE ENABLED
glEnable(GL_BLEND); // BLEND ENABLED
//glEnable(GL_TEXTURE_2D);
//glEnable(GL_BLEND);
//glDisable(GL_LIGHTING);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
//glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glBindTexture(GL_TEXTURE_2D, sun_texid);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-5000, 0.0, -5000);
glTexCoord2f(1.0f, 0.0f); glVertex3f( 5000, 0.0, -5000);
glTexCoord2f(1.0f, 1.0f); glVertex3f( 5000, 0.0, 5000);
glTexCoord2f(0.0f, 1.0f); glVertex3f(-5000, 0.0, 5000);
glEnd();
}
glPopMatrix();
xglDisable(GL_TEXTURE_2D);
glDisable(GL_BLEND);
glPushMatrix();
{
xglRotatef(((RAD_TO_DEG * rightAscension)- 90.0), 0.0, 0.0, 1.0);
xglRotatef((RAD_TO_DEG * declination), 1.0, 0.0, 0.0);
xglTranslatef(0,58600,0);
gluSphere( SunObject, sun_size, 10, 10 );
}
glPopMatrix();
glDisable(GL_TEXTURE_2D); // TEXTURE DISABLED
glDisable(GL_BLEND); // BLEND DISABLED
}
}
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