Add support transparency for landscapes (#3293)

Co-authored-by: Georg Zotti <Georg.Zotti@univie.ac.at>

guide/app_config_ini.tex

@@ -569,6 +569,8 @@ \subsection{\big[landscape\big]}
 flag\_landscape\_sets\_minimal\_brightness & bool  & Set \emph{true} to use value for minimal brightness for landscape from landscape settings.\\%\midrule
 flag\_enable\_illumination\_layer          & bool  & Set \emph{true} to use illumination layer for landscape.\\%\midrule
 flag\_enable\_labels                       & bool  & Set \emph{true} to use landscape labels from gazetteer layer.\\%\midrule
+flag\_transparency                         & bool  & Set \emph{true} to show landscape semitransparent.\\
+transparency                               & float & Use this transparency for landscapes. [0\ldots1] Typical value: \emph{0.5}\\
 atmospheric\_extinction\_coefficient       & float & Set atmospheric extinction coefficient $k$ [mag/airmass]\\%\midrule
 temperature\_C                             & float & Set atmospheric temperature [Celsius]\\%\midrule
 pressure\_mbar                             & float & Set atmospheric pressure [mbar]\\%\midrule

guide/ch_interface.tex

@@ -113,7 +113,7 @@ \section{Setting Your Location}
 ``use as default'' checkbox, disable ``Get location from Network'',
 and close the location window.
 
-Two settings may influence the Landscape when changing locations:
+Two settings may influence the landscape when changing locations:
 \begin{description}
 \item[Auto select landscapes] When changing the planet, 
 a fitting landscape panorama will be shown when available. 
@@ -776,35 +776,35 @@ \subsection{The Landscape Tab}
 The controls at the bottom right of the window operate as follows:
 
 \begin{description}
-\item[Show ground] This turns on and off landscape rendering (same
-  as the button \guibutton{0.6}{bt_ground.png} in the main tool bar).
 \item[Use this landscape as default] Selecting this option will save
   the landscape into the program configuration file so that the current
   landscape will be the one used when Stellarium starts.
-\item[Use associated planet and position] When enabled, selecting a
-  new landscape will automatically update the observer location.
-  Use this if the landscape is not just decoration, but a true
-  representation of a particular site you wish to visit in the simulation.
-\item[Show landscape labels] Landscapes can be configured with a
-  gazetteer of interesting points, e.g., mountain peaks, which can be
-  labeled with this option.
+\item[Show ground] This turns on and off landscape rendering (same
+  as the button \guibutton{0.6}{bt_ground.png} in the main tool bar).
 \item[Show fog] This turns on and off rendering of a band of
   fog/haze along the horizon, when available in this landscape.
 \item[Show illumination] to reflect the ugly developments of our
   civilisation, landscapes can be configured with a layer of light
   pollution, e.g., streetlamps, bright windows, or the sky glow of a
   nearby city. This layer, if present, will be mixed in when it is
   dark enough.
-\item[Minimal brightness] Use some minimal brightness
-  setting. Moonless night on very dark locations may appear too dark
-  on your screen. You may want to configure some minimal brightness
-  here.
+\item[Show landscape labels] Landscapes can be configured with a
+  gazetteer of interesting points, e.g., mountain peaks, which can be
+  labeled with this option. Color and font size can also be configured.
+\item[Position from landscape] When enabled, selecting a
+  new landscape will automatically update the observer location.
+  Use this if the landscape is not just decoration, but a true
+  representation of a particular site you wish to visit in the simulation.
+\item[Minimal brightness] Moonless night on very dark locations may appear too dark
+  on your screen. You may want to configure some minimal brightness here.
+  \begin{description}
 \item[from landscape, if given] Landscape authors may decide to
   provide such a minimal brightness value in the \file{landscape.ini}
   file. 
+  \end{description}
 \item[Draw only polygon]\newFeature{0.20.2} If a polygonal horizon line has been
-  defined for the landscape, only draw this. 
-\item[Polygonal line thickness]\newFeature{0.20.2} Set line width for the polygonal line.
+  defined for the landscape, only draw this with the given thickness.
+\item[Transparency] Allow peeking below the horizon. \newFeature{23.3} Note that this may show graphical errors. 
 \end{description}
 
 \noindent Using the button \menu{Add/remove landscapes\ldots}, you can also

src/core/modules/Landscape.cpp

@@ -1074,7 +1074,7 @@ void LandscapeOldStyle::drawFog(StelCore*const core, const int firstFreeTexSampl
 	renderProgram->setUniformValue(shaderVars.vshift, vpos);
 
 	const float brightness = landFader.getInterstate()*fogFader.getInterstate()*(0.1f+0.1f*landscapeBrightness);
-	renderProgram->setUniformValue(shaderVars.brightness, brightness, brightness, brightness, landFader.getInterstate());
+	renderProgram->setUniformValue(shaderVars.brightness, brightness, brightness, brightness, (1.f-landscapeTransparency)*landFader.getInterstate());
 	renderProgram->setUniformValue(shaderVars.projectionMatrixInverse, prj->getProjectionMatrix().toQMatrix().inverted());
 	prj->setUnProjectUniforms(*renderProgram);
 
@@ -1096,14 +1096,15 @@ void LandscapeOldStyle::drawDecor(StelCore*const core, const int firstFreeTexSam
 	if (drawLight)
 	{
 		const auto brightness = illumFader.getInterstate()*lightScapeBrightness;
-		renderProgram->setUniformValue(shaderVars.brightness, brightness, brightness, brightness,
-									   landFader.getInterstate());
+		renderProgram->setUniformValue(shaderVars.brightness,
+					       brightness, brightness, brightness,
+					       (1.f-landscapeTransparency)*landFader.getInterstate());
 	}
 	else
 	{
 		renderProgram->setUniformValue(shaderVars.brightness,
-									   landscapeBrightness, landscapeBrightness, landscapeBrightness,
-									   landFader.getInterstate());
+					       landscapeBrightness, landscapeBrightness, landscapeBrightness,
+					       (1.f-landscapeTransparency)*landFader.getInterstate());
 	}
 
 	renderProgram->setUniformValue(shaderVars.tanMode, tanMode);
@@ -1198,8 +1199,8 @@ void LandscapeOldStyle::drawGround(StelCore*const core, const int firstFreeTexSa
 	renderProgram->setUniformValue(shaderVars.vshift, vshift);
 	renderProgram->setUniformValue(shaderVars.projectionMatrixInverse, prj->getProjectionMatrix().toQMatrix().inverted());
 	renderProgram->setUniformValue(shaderVars.brightness,
-								   landscapeBrightness, landscapeBrightness, landscapeBrightness,
-								   landFader.getInterstate());
+				       landscapeBrightness, landscapeBrightness, landscapeBrightness,
+				       (1.f-landscapeTransparency)*landFader.getInterstate());
 	prj->setUnProjectUniforms(*renderProgram);
 	gl.glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 }
@@ -1264,7 +1265,7 @@ void LandscapeOldStyle::drawFogLowGL(StelCore* core, StelPainter& sPainter) cons
 	transfo->combine(Mat4d::translation(Vec3d(0.,0.,static_cast<double>(vpos))));
 	sPainter.setProjector(core->getProjection(transfo));
 	sPainter.setBlending(true, GL_ONE, GL_ONE);
-	sPainter.setColor(Vec3f(landFader.getInterstate()*fogFader.getInterstate()*(0.1f+0.1f*landscapeBrightness)), landFader.getInterstate());
+	sPainter.setColor(Vec3f(landFader.getInterstate()*fogFader.getInterstate()*(0.1f+0.1f*landscapeBrightness)), (1.f-landscapeTransparency)*landFader.getInterstate());
 	fogTex->bind();
 	const double height = radius * static_cast<double>(calibrated?
 				(std::tan((fogAltAngle+fogAngleShift)*M_PI_180f) - std::tan(fogAngleShift*M_PI_180f))
@@ -1283,9 +1284,9 @@ void LandscapeOldStyle::drawDecorLowGL(StelCore* core, StelPainter& sPainter, co
 	if (landFader.getInterstate()==0.f)
 		return;
 	if (drawLight)
-		sPainter.setColor(Vec3f(illumFader.getInterstate()*lightScapeBrightness), landFader.getInterstate());
+		sPainter.setColor(Vec3f(illumFader.getInterstate()*lightScapeBrightness), (1.f-landscapeTransparency)*landFader.getInterstate());
 	else
-		sPainter.setColor(Vec3f(landscapeBrightness), landFader.getInterstate());
+		sPainter.setColor(Vec3f(landscapeBrightness), (1.f-landscapeTransparency)*landFader.getInterstate());
 
 	for (const auto& side : precomputedSides)
 	{
@@ -1307,7 +1308,7 @@ void LandscapeOldStyle::drawGroundLowGL(StelCore* core, StelPainter& sPainter) c
 	transfo->combine(Mat4d::zrotation(groundAngleRotateZ-static_cast<double>(angleRotateZOffset)) * Mat4d::translation(Vec3d(0,0,static_cast<double>(vshift))));
 
 	sPainter.setProjector(core->getProjection(transfo));
-	sPainter.setColor(landscapeBrightness, landscapeBrightness, landscapeBrightness, landFader.getInterstate());
+	sPainter.setColor(landscapeBrightness, landscapeBrightness, landscapeBrightness, (1.f-landscapeTransparency)*landFader.getInterstate());
 
 	if(groundTex.isNull())
 	{
@@ -1458,7 +1459,7 @@ void LandscapePolygonal::draw(StelCore* core, bool onlyPolygon)
 
 	if (!onlyPolygon) // The only useful application of the onlyPolygon is a demo which does not fill the polygon
 	{
-		sPainter.setColor(landscapeBrightness*groundColor, landFader.getInterstate());
+		sPainter.setColor(landscapeBrightness*groundColor, (1.f-landscapeTransparency)*landFader.getInterstate());
 #ifdef GL_MULTISAMPLE
 		const auto gl = sPainter.glFuncs();
 		if (multisamplingEnabled_)
@@ -2033,7 +2034,7 @@ void main(void)
 
 		renderProgram->setUniformValue(shaderVars.brightness,
 									   landscapeBrightness, landscapeBrightness,
-									   landscapeBrightness, landFader.getInterstate());
+									   landscapeBrightness, (1.f-landscapeTransparency)*landFader.getInterstate());
 		const int mainTexSampler = 0;
 		mapTex->bind(mainTexSampler);
 		renderProgram->setUniformValue(shaderVars.mapTex, mainTexSampler);
@@ -2063,8 +2064,9 @@ void main(void)
 			const float brightness = landFader.getInterstate()*fogFader.getInterstate()*(0.1f+0.1f*landscapeBrightness);
 
 			renderProgram->setUniformValue(shaderVars.bottomCapColor, 0.f, 0.f, 0.f, 0.f);
-			renderProgram->setUniformValue(shaderVars.brightness, brightness, brightness, brightness,
-										   landFader.getInterstate());
+			renderProgram->setUniformValue(shaderVars.brightness,
+						       brightness, brightness, brightness,
+						       (1.f-landscapeTransparency)*landFader.getInterstate());
 			mapTexFog->bind();
 			renderProgram->setUniformValue(shaderVars.mapTexTop, fogTexTop);
 			renderProgram->setUniformValue(shaderVars.mapTexBottom, fogTexBottom);
@@ -2077,8 +2079,9 @@ void main(void)
 			gl.glBlendFunc(GL_SRC_ALPHA, GL_ONE);
 			const float brightness = lightScapeBrightness*illumFader.getInterstate();
 			renderProgram->setUniformValue(shaderVars.bottomCapColor, 0.f, 0.f, 0.f, 0.f);
-			renderProgram->setUniformValue(shaderVars.brightness, brightness, brightness, brightness,
-										   landFader.getInterstate());
+			renderProgram->setUniformValue(shaderVars.brightness,
+						       brightness, brightness, brightness,
+						       (1.f-landscapeTransparency)*landFader.getInterstate());
 			mapTexIllum->bind();
 			renderProgram->setUniformValue(shaderVars.mapTexTop, illumTexTop);
 			renderProgram->setUniformValue(shaderVars.mapTexBottom, illumTexBottom);

src/core/modules/Landscape.hpp

@@ -136,7 +136,7 @@ class Landscape
 	//! Get color for landscape labels
 	Vec3f getLabelColor() const { return labelColor; }
 	//! Set color for landscape labels
-	void setLabelColor(const Vec3f& c) { labelColor=c; };
+	void setLabelColor(const Vec3f& c) { labelColor=c; }
 
 	//! Get landscape name
 	QString getName() const {return name;}
@@ -179,6 +179,8 @@ class Landscape
 	//! Get the sine of the limiting altitude (can be used to short-cut drawing below horizon, like star fields). There is no set here, value is only from landscape.ini
 	double getSinMinAltitudeLimit() const {return sinMinAltitudeLimit;}
 
+	void setTransparency(const double f) { landscapeTransparency=f; }
+
 	//! Find opacity in a certain direction. (New in V0.13 series)
 	//! can be used to find sunrise or visibility questions on the real-world landscape horizon.
 	//! Default implementation indicates the horizon equals math horizon.
@@ -253,6 +255,7 @@ class Landscape
 				  //! Not in landscape.ini: Used in special cases where the horizon may rotate, e.g. on a ship.
 
 	double sinMinAltitudeLimit; //! Minimal altitude of landscape cover. Can be used to construct bounding caps, so that e.g. no stars are drawn below this altitude. Default -0.035, i.e. sin(-2 degrees).
+	double landscapeTransparency;
 
 	StelLocation location; //! OPTIONAL. If present, can be used to set location.
 	/** May be given in landscape.ini:light_pollution_luminance in cd/m². Default: no change.

src/core/modules/LandscapeMgr.cpp

@@ -359,6 +359,8 @@ LandscapeMgr::LandscapeMgr()
 	, defaultMinimalBrightness(0.01)
 	, flagLandscapeSetsMinimalBrightness(false)
 	, flagEnvironmentAutoEnabling(false)
+	, flagLandscapeUseTransparency(false)
+	, landscapeTransparency(0.)
 {
 	setObjectName("LandscapeMgr"); // should be done by StelModule's constructor.
 
@@ -647,6 +649,8 @@ void LandscapeMgr::update(double deltaTime)
 	}
 
 	landscape->setBrightness(landscapeBrightness, lightscapeBrightness);
+	if (getFlagLandscapeUseTransparency())
+		landscape->setTransparency(landscapeTransparency);
 
 	messageFader.update(static_cast<int>(deltaTime*1000));
 }
@@ -850,6 +854,9 @@ void LandscapeMgr::init()
 	setLabelFontSize(conf->value("landscape/label_font_size", 18).toInt());
 	setLabelColor(Vec3f(conf->value("landscape/label_color", "0.2,0.8,0.2").toString()));
 
+	setFlagLandscapeUseTransparency(conf->value("landscape/flag_transparency", false).toBool());
+	setLandscapeTransparency(conf->value("landscape/transparency", 0.5).toDouble());
+
 	cardinalPoints = new Cardinals();
 	cardinalPoints->setFlagShow4WCRLabels(conf->value("viewing/flag_cardinal_points", true).toBool());
 	cardinalPoints->setFlagShow8WCRLabels(conf->value("viewing/flag_ordinal_points", true).toBool());
@@ -1113,7 +1120,10 @@ bool LandscapeMgr::getIsLandscapeFullyVisible() const
 
 double LandscapeMgr::getLandscapeSinMinAltitudeLimit() const
 {
-	return landscape->getSinMinAltitudeLimit();
+	if (flagLandscapeUseTransparency && landscapeTransparency>0.)
+		return -1.;
+	else
+		return landscape->getSinMinAltitudeLimit();
 }
 
 bool LandscapeMgr::getFlagUseLightPollutionFromDatabase() const
@@ -1257,6 +1267,17 @@ bool LandscapeMgr::getFlagIllumination() const
 	return landscape->getFlagShowIllumination();
 }
 
+void LandscapeMgr::setLandscapeTransparency(const double f)
+{
+	landscapeTransparency = f;
+	emit landscapeDisplayedChanged(f);
+}
+
+double LandscapeMgr::getLandscapeTransparency() const
+{
+	return landscapeTransparency;
+}
+
 void LandscapeMgr::setFlagLabels(const bool displayed)
 {
 	if (landscape->getFlagShowLabels() != displayed) {

src/core/modules/LandscapeMgr.hpp

@@ -274,6 +274,14 @@ class LandscapeMgr : public StelModule
 		   READ getLabelColor
 		   WRITE setLabelColor
 		   NOTIFY labelColorChanged)
+	Q_PROPERTY(double landscapeTransparency
+		   READ getLandscapeTransparency
+		   WRITE setLandscapeTransparency
+		   NOTIFY landscapeTransparencyChanged)
+	Q_PROPERTY(bool flagLandscapeUseTransparency
+		   READ getFlagLandscapeUseTransparency
+		   WRITE setFlagLandscapeUseTransparency
+		   NOTIFY flagLandscapeUseTransparencyChanged)
 
 public:
 	LandscapeMgr();
@@ -556,6 +564,23 @@ public slots:
 	//! Set atmosphere fade duration in s.
 	void setAtmosphereFadeDuration(const float f);
 
+	double getLandscapeTransparency() const;
+	void setLandscapeTransparency(const double f);
+	//! Return the value of the flag determining if a transparency should be used.
+	bool getFlagLandscapeUseTransparency() const {return flagLandscapeUseTransparency; }
+	//! Set the value of the flag determining if a transparency should be used.
+	void setFlagLandscapeUseTransparency(bool b)
+	{
+		if (b!=flagLandscapeUseTransparency)
+		{
+			flagLandscapeUseTransparency=b;
+			emit flagLandscapeUseTransparencyChanged(b);
+		}
+		if (b==false)
+			landscape->setTransparency(0.0);
+	}
+
+
 	/*
 	//This method has been removed, use StelSkyDrawer::getBortleScaleIndex instead, or StelMainScriptAPI::getBortleScaleIndex in scripts
 	//Also, if required, please use StelSkyDrawer::setBortleScaleIndex or StelMainScriptAPI::setBortleScaleIndex instead of LandscapeMgr::setAtmosphereBortleLightPollution
@@ -702,6 +727,8 @@ public slots:
 	void flagLandscapeSetsMinimalBrightnessChanged(const bool value);
 	void defaultMinimalBrightnessChanged(const double value);
 	void setFlagEnvironmentAutoEnableChanged(const bool enabled);
+	void landscapeTransparencyChanged(const double value);
+	void flagLandscapeUseTransparencyChanged(const bool value);
 
 	//! Emitted whenever the default landscape is changed
 	//! @param id the landscape id of the new default landscape
@@ -810,6 +837,11 @@ private slots:
 	//! Indicate auto-enable atmosphere and landscape for planets with atmospheres in location window
 	bool flagEnvironmentAutoEnabling;
 
+	//! Indicate use of the default transparency value specified in config.ini.
+	bool flagLandscapeUseTransparency;
+	//! A transparency value
+	double landscapeTransparency;
+
 	//! The ID of the currently loaded landscape
 	QString currentLandscapeID;
 

src/gui/ConfigurationDialog.cpp

@@ -1085,6 +1085,8 @@ void ConfigurationDialog::saveAllSettings()
 	conf->setValue("landscape/flag_minimal_brightness",                propMgr->getStelPropertyValue("LandscapeMgr.flagLandscapeUseMinimalBrightness").toBool());
 	conf->setValue("landscape/flag_landscape_sets_minimal_brightness", propMgr->getStelPropertyValue("LandscapeMgr.flagLandscapeSetsMinimalBrightness").toBool());
 	conf->setValue("landscape/minimal_brightness",                     propMgr->getStelPropertyValue("LandscapeMgr.defaultMinimalBrightness").toFloat());
+	conf->setValue("landscape/flag_transparency",                      propMgr->getStelPropertyValue("LandscapeMgr.flagLandscapeUseTransparency").toBool());
+	conf->setValue("landscape/transparency",                           propMgr->getStelPropertyValue("LandscapeMgr.landscapeTransparency").toFloat());
 	conf->setValue("landscape/flag_polyline_only",                     propMgr->getStelPropertyValue("LandscapeMgr.flagPolyLineDisplayedOnly").toBool());
 	conf->setValue("landscape/polyline_thickness",                     propMgr->getStelPropertyValue("LandscapeMgr.polyLineThickness").toInt());
 	conf->setValue("stars/init_light_pollution_luminance",             propMgr->getStelPropertyValue("StelSkyDrawer.lightPollutionLuminance").toFloat());

src/gui/ViewDialog.cpp

@@ -347,6 +347,8 @@ void ViewDialog::createDialogContent()
 	ui->localLandscapeBrightnessCheckBox->setEnabled(lmgr->property("flagLandscapeUseMinimalBrightness").toBool());
 	ui->landscapeBrightnessSpinBox->setEnabled(lmgr->property("flagLandscapeUseMinimalBrightness").toBool());
 	connectDoubleProperty(ui->landscapeBrightnessSpinBox,"LandscapeMgr.defaultMinimalBrightness");
+	connectBoolProperty(ui->landscapeTransparencyCheckBox,"LandscapeMgr.flagLandscapeUseTransparency");
+	connectDoubleProperty(ui->landscapeTransparencySpinBox,"LandscapeMgr.landscapeTransparency");
 	connectBoolProperty(ui->localLandscapeBrightnessCheckBox,"LandscapeMgr.flagLandscapeSetsMinimalBrightness");
 	connectBoolProperty(ui->landscapePolylineCheckBox, "LandscapeMgr.flagPolyLineDisplayedOnly");
 	connectIntProperty(ui->landscapePolylineThicknessSpinBox, "LandscapeMgr.polyLineThickness");