From 06f2dba92c5403fc5563585069d5f017096374eb Mon Sep 17 00:00:00 2001 From: curt Date: Tue, 29 May 2001 13:45:06 +0000 Subject: [PATCH] Norman Vine contributed an optimization to eliminate unnecessary color recalculations. --- simgear/sky/stars.cxx | 135 +++++++++++++++++++++++------------------- 1 file changed, 75 insertions(+), 60 deletions(-) diff --git a/simgear/sky/stars.cxx b/simgear/sky/stars.cxx index 274b100a..920f2477 100644 --- a/simgear/sky/stars.cxx +++ b/simgear/sky/stars.cxx @@ -44,7 +44,7 @@ SG_USING_STD(endl); // Set up star rendering call backs static int sgStarPreDraw( ssgEntity *e ) { /* cout << endl << "Star pre draw" << endl << "----------------" - << endl << endl; */ + << endl << endl; */ ssgLeaf *f = (ssgLeaf *)e; if ( f -> hasState () ) f->getState()->apply() ; @@ -60,7 +60,7 @@ static int sgStarPreDraw( ssgEntity *e ) { static int sgStarPostDraw( ssgEntity *e ) { /* cout << endl << "Star post draw" << endl << "----------------" - << endl << endl; */ + << endl << endl; */ glPopAttrib(); @@ -86,7 +86,7 @@ ssgBranch * SGStars::build( int num, sgdVec3 *star_data, double star_dist ) { sgVec4 color; if ( star_data == NULL ) { - cout << "WARNING: null star data passed to SGStars::build()" << endl; + cout << "WARNING: null star data passed to SGStars::build()" << endl; } // set up the orb state @@ -106,27 +106,27 @@ ssgBranch * SGStars::build( int num, sgdVec3 *star_data, double star_dist ) { // cl = new ssgColourArray( 1 ); // sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 ); // cl->add( color ); - + // Build ssg structure sgVec3 p; for ( int i = 0; i < num; ++i ) { - // position seeded to arbitrary values - sgSetVec3( p, - star_dist * cos( star_data[i][0] ) - * cos( star_data[i][1] ), + // position seeded to arbitrary values + sgSetVec3( p, + star_dist * cos( star_data[i][0] ) + * cos( star_data[i][1] ), star_dist * sin( star_data[i][0] ) - * cos( star_data[i][1] ), + * cos( star_data[i][1] ), star_dist * sin( star_data[i][1] ) - ); - vl->add( p ); + ); + vl->add( p ); - // color (magnitude) - sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 ); - cl->add( color ); + // color (magnitude) + sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 ); + cl->add( color ); } ssgLeaf *stars_obj = - new ssgVtxTable ( GL_POINTS, vl, NULL, NULL, cl ); + new ssgVtxTable ( GL_POINTS, vl, NULL, NULL, cl ); stars_obj->setState( state ); stars_obj->setCallback( SSG_CALLBACK_PREDRAW, sgStarPreDraw ); stars_obj->setCallback( SSG_CALLBACK_POSTDRAW, sgStarPostDraw ); @@ -154,62 +154,77 @@ 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; + // 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; + 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; + 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; + 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; + 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; + 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; + factor = 0.75; + cutoff = 0.6; + phase = 6; } else { - // early dusk or late dawn - factor = 0.7; - cutoff = 0.0; + // early dusk or late dawn + factor = 0.7; + cutoff = 0.0; + phase = 7; } - 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. - - // color (magnitude) - mag = star_data[i][2]; - if ( mag < cutoff ) { - nmag = ( 4.5 - mag ) / 5.5; // translate to 0 ... 1.0 scale - // alpha = nmag * 0.7 + 0.3; // translate to a 0.3 ... 1.0 scale - alpha = nmag * 0.85 + 0.15; // translate to a 0.15 ... 1.0 scale - alpha *= factor; // dim when the sun is brighter - } else { - alpha = 0.0; - } - - if (alpha > 1.0) { alpha = 1.0; } - if (alpha < 0.0) { alpha = 0.0; } - - color = cl->get( i ); - sgSetVec4( color, 1.0, 1.0, 1.0, alpha ); - // cout << "alpha[" << i << "] = " << alpha << endl; + 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. + + // color (magnitude) + mag = star_data[i][2]; + if ( mag < cutoff ) { + nmag = ( 4.5 - mag ) / 5.5; // translate to 0 ... 1.0 scale + // alpha = nmag * 0.7 + 0.3; // translate to a 0.3 ... 1.0 scale + alpha = nmag * 0.85 + 0.15; // translate to a 0.15 ... 1.0 scale + alpha *= factor; // dim when the sun is brighter + } else { + alpha = 0.0; + } + + if (alpha > 1.0) { alpha = 1.0; } + if (alpha < 0.0) { alpha = 0.0; } + + color = cl->get( i ); + sgSetVec4( color, 1.0, 1.0, 1.0, alpha ); + // cout << "alpha[" << i << "] = " << alpha << endl; + } } // cout << "min = " << min << " max = " << max << " count = " << num -- 2.39.5