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Norman Vine contributed an optimization to eliminate unnecessary color

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recalculations.
This commit is contained in:
curt 2001-05-29 13:45:06 +00:00
parent 30a14741c9
commit 06f2dba92c
1 changed files with 71 additions and 56 deletions
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25
simgear/sky/stars.cxx
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@ -154,44 +154,58 @@ bool SGStars::repaint( double sun_angle, int num, sgdVec3 *star_data ) {
double mag, nmag, alpha, factor, cutoff;
float *color;
static int old_phase = -1;
int phase;
// determine which star structure to draw
if ( sun_angle > (0.5 * SGD_PI + 10.0 * SGD_DEGREES_TO_RADIANS ) ) {
// deep night
factor = 1.0;
cutoff = 4.5;
phase = 0;
} else if ( sun_angle > (0.5 * SGD_PI + 8.8 * SGD_DEGREES_TO_RADIANS ) ) {
factor = 1.0;
cutoff = 3.8;
phase = 1;
} else if ( sun_angle > (0.5 * SGD_PI + 7.5 * SGD_DEGREES_TO_RADIANS ) ) {
factor = 0.95;
cutoff = 3.1;
phase = 2;
} else if ( sun_angle > (0.5 * SGD_PI + 7.0 * SGD_DEGREES_TO_RADIANS ) ) {
factor = 0.9;
cutoff = 2.4;
phase = 3;
} else if ( sun_angle > (0.5 * SGD_PI + 6.5 * SGD_DEGREES_TO_RADIANS ) ) {
factor = 0.85;
cutoff = 1.8;
phase = 4;
} else if ( sun_angle > (0.5 * SGD_PI + 6.0 * SGD_DEGREES_TO_RADIANS ) ) {
factor = 0.8;
cutoff = 1.2;
phase = 5;
} else if ( sun_angle > (0.5 * SGD_PI + 5.5 * SGD_DEGREES_TO_RADIANS ) ) {
factor = 0.75;
cutoff = 0.6;
phase = 6;
} else {
// early dusk or late dawn
factor = 0.7;
cutoff = 0.0;
phase = 7;
}
if( phase != old_phase ) {
old_phase = phase;
for ( int i = 0; i < num; ++i ) {
// if ( star_data[i][2] < min ) { min = star_data[i][2]; }
// if ( star_data[i][2] > max ) { max = star_data[i][2]; }
// magnitude ranges from -1 (bright) to 4 (dim). The range of
// star and planet magnitudes can actually go outside of this,
// but for our purpose, if it is brighter that -1, we'll color
// it full white/alpha anyway and 4 is a convenient cutoff
// point which keeps the number of stars drawn at about 500.
// magnitude ranges from -1 (bright) to 4 (dim). The
// range of star and planet magnitudes can actually go
// outside of this, but for our purpose, if it is brighter
// that -1, we'll color it full white/alpha anyway and 4
// is a convenient cutoff point which keeps the number of
// stars drawn at about 500.
// color (magnitude)
mag = star_data[i][2];
@ -211,6 +225,7 @@ bool SGStars::repaint( double sun_angle, int num, sgdVec3 *star_data ) {
sgSetVec4( color, 1.0, 1.0, 1.0, alpha );
// cout << "alpha[" << i << "] = " << alpha << endl;
}
}
// cout << "min = " << min << " max = " << max << " count = " << num
// << endl;