curt
efce88ff12
- In sky.cxx blend low density cloud layers (few/scattered) into nothing (but don't touch visibility distance) as we approach them so we can fly through clean. - For high density cloud layers (broken/overcast) we do not fade the layers out, but we fade visibility to nearly nothing as we approach the layer.
386 lines
11 KiB
C++
386 lines
11 KiB
C++
// sky.cxx -- ssg based sky model
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//
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// Written by Curtis Olson, started December 1997.
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// SSG-ified by Curtis Olson, February 2000.
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//
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// Copyright (C) 1997-2000 Curtis L. Olson - http://www.flightgear.org/~curt
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Library General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Library General Public License for more details.
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//
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// You should have received a copy of the GNU Library General Public
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// License along with this library; if not, write to the
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// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, USA.
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//
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// $Id$
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#include <plib/sg.h>
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#include <plib/ssg.h>
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#include <simgear/math/sg_random.h>
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#include "sky.hxx"
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// Constructor
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SGSky::SGSky( void ) {
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effective_visibility = visibility = 10000.0;
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// near cloud visibility state variables
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in_puff = false;
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puff_length = 0;
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puff_progression = 0;
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ramp_up = 0.15;
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ramp_down = 0.15;
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// ramp_up = 4.0;
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// ramp_down = 4.0;
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in_cloud = -1;
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}
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// Destructor
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SGSky::~SGSky( void )
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{
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for (unsigned int i = 0; i < cloud_layers.size(); i++)
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delete cloud_layers[i];
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}
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// initialize the sky and connect the components to the scene graph at
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// the provided branch
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void SGSky::build( double h_radius_m, double v_radius_m,
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double sun_size, double moon_size,
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int nplanets, sgdVec3 *planet_data,
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int nstars, sgdVec3 *star_data )
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{
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pre_root = new ssgRoot;
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post_root = new ssgRoot;
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pre_selector = new ssgSelector;
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post_selector = new ssgSelector;
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pre_transform = new ssgTransform;
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post_transform = new ssgTransform;
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dome = new SGSkyDome;
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pre_transform -> addKid( dome->build( h_radius_m, v_radius_m ) );
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planets = new SGStars;
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pre_transform -> addKid(planets->build(nplanets, planet_data, h_radius_m));
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stars = new SGStars;
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pre_transform -> addKid( stars->build(nstars, star_data, h_radius_m) );
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moon = new SGMoon;
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pre_transform -> addKid( moon->build(tex_path, moon_size) );
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oursun = new SGSun;
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pre_transform -> addKid( oursun->build(tex_path, sun_size) );
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pre_selector->addKid( pre_transform );
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pre_selector->clrTraversalMaskBits( SSGTRAV_HOT );
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post_selector->addKid( post_transform );
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post_selector->clrTraversalMaskBits( SSGTRAV_HOT );
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pre_root->addKid( pre_selector );
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post_root->addKid( post_selector );
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}
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// repaint the sky components based on current value of sun_angle,
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// sky, and fog colors.
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//
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// sun angle in degrees relative to verticle
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// 0 degrees = high noon
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// 90 degrees = sun rise/set
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// 180 degrees = darkest midnight
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bool SGSky::repaint( const SGSkyColor &sc )
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{
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if ( effective_visibility > 1000.0 ) {
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enable();
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dome->repaint( sc.sky_color, sc.fog_color, sc.sun_angle,
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effective_visibility );
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stars->repaint( sc.sun_angle, sc.nstars, sc.star_data );
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planets->repaint( sc.sun_angle, sc.nplanets, sc.planet_data );
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oursun->repaint( sc.sun_angle, effective_visibility );
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moon->repaint( sc.moon_angle );
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for ( int i = 0; i < (int)cloud_layers.size(); ++i ) {
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if (cloud_layers[i]->getCoverage() != SGCloudLayer::SG_CLOUD_CLEAR){
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cloud_layers[i]->repaint( sc.cloud_color );
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}
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}
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} else {
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// turn off sky
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disable();
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}
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return true;
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}
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// reposition the sky at the specified origin and orientation
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//
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// lon specifies a rotation about the Z axis
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// lat specifies a rotation about the new Y axis
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// spin specifies a rotation about the new Z axis (this allows
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// additional orientation for the sunrise/set effects and is used by
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// the skydome and perhaps clouds.
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bool SGSky::reposition( SGSkyState &st, double dt )
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{
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double angle = st.gst * 15; // degrees
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dome->reposition( st.zero_elev, st.lon, st.lat, st.spin );
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stars->reposition( st.view_pos, angle );
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planets->reposition( st.view_pos, angle );
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oursun->reposition( st.view_pos, angle,
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st.sun_ra, st.sun_dec, st.sun_dist );
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moon->reposition( st.view_pos, angle,
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st.moon_ra, st.moon_dec, st.moon_dist );
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for ( int i = 0; i < (int)cloud_layers.size(); ++i ) {
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if ( cloud_layers[i]->getCoverage() != SGCloudLayer::SG_CLOUD_CLEAR ) {
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cloud_layers[i]->reposition( st.zero_elev, st.view_up,
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st.lon, st.lat, st.alt, dt );
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}
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}
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return true;
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}
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// draw background portions of the sky ... do this before you draw the
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// rest of your scene.
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void SGSky::preDraw( float alt, float fog_exp2_density ) {
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ssgCullAndDraw( pre_root );
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// if we are closer than this to a cloud layer, don't draw clouds
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static const float slop = 5.0;
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int i;
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// check where we are relative to the cloud layers
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in_cloud = -1;
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for ( i = 0; i < (int)cloud_layers.size(); ++i ) {
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float asl = cloud_layers[i]->getElevation_m();
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float thickness = cloud_layers[i]->getThickness_m();
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if ( alt < asl - slop ) {
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// below cloud layer
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} else if ( alt < asl + thickness + slop ) {
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// in cloud layer
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// bail now and don't draw any clouds
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in_cloud = i;
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} else {
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// above cloud layer
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}
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}
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// determine rendering order
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cur_layer_pos = 0;
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while ( cur_layer_pos < (int)cloud_layers.size() &&
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alt > cloud_layers[cur_layer_pos]->getElevation_m() )
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{
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++cur_layer_pos;
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}
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// FIXME: This should not be needed, but at this time (08/15/2003)
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// certain NVidia drivers don't seem to implement
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// glPushAttrib(FG_FOG_BIT) properly. The result is that
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// there is not fog when looking at the sun.
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glFogf ( GL_FOG_DENSITY, fog_exp2_density );
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}
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void SGSky::drawUpperClouds( ) {
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// draw the cloud layers that are above us, top to bottom
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for ( int i = (int)cloud_layers.size() - 1; i >= cur_layer_pos; --i ) {
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if ( i != in_cloud ) {
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cloud_layers[i]->draw( false );
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}
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}
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}
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// draw translucent clouds ... do this after you've drawn all the
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// oapaque elements of your scene.
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void SGSky::drawLowerClouds() {
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// draw the cloud layers that are below us, bottom to top
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for ( int i = 0; i < cur_layer_pos; ++i ) {
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if ( i != in_cloud ) {
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cloud_layers[i]->draw( true );
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}
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}
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}
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void
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SGSky::add_cloud_layer( SGCloudLayer * layer )
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{
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cloud_layers.push_back(layer);
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}
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const SGCloudLayer *
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SGSky::get_cloud_layer (int i) const
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{
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return cloud_layers[i];
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}
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SGCloudLayer *
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SGSky::get_cloud_layer (int i)
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{
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return cloud_layers[i];
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}
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int
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SGSky::get_cloud_layer_count () const
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{
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return cloud_layers.size();
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}
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// modify the current visibility based on cloud layers, thickness,
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// transition range, and simulated "puffs".
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void SGSky::modify_vis( float alt, float time_factor ) {
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float effvis = visibility;
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for ( int i = 0; i < (int)cloud_layers.size(); ++i ) {
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float asl = cloud_layers[i]->getElevation_m();
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float thickness = cloud_layers[i]->getThickness_m();
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float transition = cloud_layers[i]->getTransition_m();
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double ratio = 1.0;
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if ( cloud_layers[i]->getCoverage() == SGCloudLayer::SG_CLOUD_CLEAR ) {
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// less than 50% coverage -- assume we're in the clear for now
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ratio = 1.0;
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} else if ( alt < asl - transition ) {
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// below cloud layer
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ratio = 1.0;
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} else if ( alt < asl ) {
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// in lower transition
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ratio = (asl - alt) / transition;
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} else if ( alt < asl + thickness ) {
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// in cloud layer
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ratio = 0.0;
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} else if ( alt < asl + thickness + transition ) {
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// in upper transition
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ratio = (alt - (asl + thickness)) / transition;
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} else {
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// above cloud layer
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ratio = 1.0;
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}
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if ( cloud_layers[i]->getCoverage() == SGCloudLayer::SG_CLOUD_CLEAR ) {
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// do nothing, clear layers aren't drawn, don't affect
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// visibility andn dont' need to be faded in or out.
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} else if ( (cloud_layers[i]->getCoverage() ==
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SGCloudLayer::SG_CLOUD_FEW)
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|| (cloud_layers[i]->getCoverage() ==
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SGCloudLayer::SG_CLOUD_SCATTERED) )
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{
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// set the alpha fade value for the cloud layer. For less
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// dense cloud layers we fade the layer to nothing as we
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// approach it because we stay clear visibility-wise as we
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// pass through it.
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float temp = ratio * 2.0;
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if ( temp > 1.0 ) { temp = 1.0; }
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cloud_layers[i]->setAlpha( temp );
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// don't touch visibility
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} else {
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// maintain full alpha for denser cloud layer types.
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// Let's set the value explicitly in case someone changed
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// the layer type.
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cloud_layers[i]->setAlpha( 1.0 );
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// lower visibility as we approach the cloud layer.
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// accumulate effects from multiple cloud layers
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effvis *= ratio;
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}
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#if 0
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if ( ratio < 1.0 ) {
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if ( ! in_puff ) {
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// calc chance of entering cloud puff
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double rnd = sg_random();
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double chance = rnd * rnd * rnd;
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if ( chance > 0.95 /* * (diff - 25) / 50.0 */ ) {
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in_puff = true;
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puff_length = sg_random() * 2.0; // up to 2 seconds
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puff_progression = 0.0;
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}
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}
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if ( in_puff ) {
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// modify actual_visibility based on puff envelope
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if ( puff_progression <= ramp_up ) {
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double x = 0.5 * SGD_PI * puff_progression / ramp_up;
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double factor = 1.0 - sin( x );
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// cout << "ramp up = " << puff_progression
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// << " factor = " << factor << endl;
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effvis = effvis * factor;
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} else if ( puff_progression >= ramp_up + puff_length ) {
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double x = 0.5 * SGD_PI *
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(puff_progression - (ramp_up + puff_length)) /
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ramp_down;
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double factor = sin( x );
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// cout << "ramp down = "
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// << puff_progression - (ramp_up + puff_length)
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// << " factor = " << factor << endl;
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effvis = effvis * factor;
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} else {
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effvis = 0.0;
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}
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/* cout << "len = " << puff_length
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<< " x = " << x
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<< " factor = " << factor
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<< " actual_visibility = " << actual_visibility
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<< endl; */
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// time_factor = ( global_multi_loop *
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// current_options.get_speed_up() ) /
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// (double)current_options.get_model_hz();
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puff_progression += time_factor;
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// cout << "time factor = " << time_factor << endl;
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/* cout << "gml = " << global_multi_loop
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<< " speed up = " << current_options.get_speed_up()
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<< " hz = " << current_options.get_model_hz() << endl;
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*/
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if ( puff_progression > puff_length + ramp_up + ramp_down) {
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in_puff = false;
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}
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}
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}
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#endif
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// never let visibility drop below 25 meters
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if ( effvis <= 25.0 ) {
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effvis = 25.0;
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}
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} // for
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effective_visibility = effvis;
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}
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