Avoid flickering of borderline ellipses

- also docfix
- make option immediately permanent

Author: gzotti

src/core/StelPainter.cpp

@@ -1740,20 +1740,18 @@ void StelPainter::drawCircle(float x, float y, float r)
 // rx: radius in x axis
 // ry: radius in y axis
 // angle rotation (counterclockwise), radians [0..2pi]
-void StelPainter::drawEllipse(float x, float y, float rX, float rY, float angle)
+void StelPainter::drawEllipse(double x, double y, double rX, double rY, double angle)
 {
-	if (rX <= 1.0f || rY <= 1.0f)
+	if (rX <= 1.0 || rY <= 1.0)
 		return;
 	// Taken largely from Nebula::renderEllipticMarker()
-	// Take into account device pixel density and global scale ratio, as we are drawing 2D stuff.
-	//const auto pixelRatio = getProjector()->getDevicePixelsPerPixel();
-	const auto scale = StelApp::getInstance().getGlobalScalingRatio();
+	const double scale = StelApp::getInstance().getGlobalScalingRatio();
 	rX *= scale;
 	rY *= scale;
 
 	//const float radiusY = 0.35 * size;
 	//const float radiusX = aspectRatio * radiusY;
-	const int numPoints = std::lround(std::clamp(qMax(rX, rY)/3, 32.f, 1024.f));
+	const int numPoints = std::lround(std::clamp(qMax(rX, rY)/3, 32., 1024.));
 	std::vector<float> vertexData;
 	vertexData.reserve(numPoints*2);
 	const float*const cossin = StelUtils::ComputeCosSinTheta(numPoints);
@@ -1769,7 +1767,7 @@ void StelPainter::drawEllipse(float x, float y, float rX, float rY, float angle)
 	}
 	const auto vertCount = vertexData.size() / 2;
 	setLineSmooth(true);
-	setLineWidth(scale * std::clamp(qMax(rX, rY)/40, 1.f, 2.f));
+	setLineWidth(scale * std::clamp(qMax(rX, rY)/40, 1., 2.));
 	enableClientStates(true);
 	setVertexPointer(2, GL_FLOAT, vertexData.data());
 	drawFromArray(StelPainter::LineLoop, vertCount, 0, false);

src/core/StelPainter.hpp

@@ -139,7 +139,7 @@ class StelPainter : protected QOpenGLFunctions
 	//! @param rx: radius in x axis
 	//! @param ry: radius in y axis
 	//! @param angle: rotation (counterclockwise), radians [0..2pi]
-	void drawEllipse(float x, float y, float rx, float ry, float angle);
+	void drawEllipse(double x, double y, double rx, double ry, double angle);
 
 	//! Draw a square using the current texture at the given projected 2d position.
 	//! This method is not thread safe.

src/core/modules/NomenclatureItem.cpp

@@ -392,25 +392,29 @@ void NomenclatureItem::draw(StelCore* core, StelPainter *painter)
 		const float brightness=(nType>=NomenclatureItem::niSpecialPointPole ? 0.5f : (solarAltitude<0. ? 0.25f : 1.0f));
 		painter->setColor(color*brightness, labelsFader.getInterstate());
 		painter->drawCircle(static_cast<float>(srcPos[0]), static_cast<float>(srcPos[1]), 2.f);
-		if (flagOutlineCraters && (nType==niCrater || nType==niSatelliteFeature)) // probably all satellite features are satellite craters
+		// Highlight a few mostly circular classes with ellipses:
+		// - Craters
+		// - Satellite features (presumably all of these are satellite craters)
+		// - Lunar Maria. Mare Frigoris is elongated, and an ellipse would extend over the Lunar rim.
+		if (flagOutlineCraters && (nType==niCrater || nType==niSatelliteFeature || (nType==niMare && englishName!="Mare Frigoris")))
 		{
 			// Compute aspectRatio and angle from position of planet and own position, parallactic angle, ...
-			double ra, de, raPl, dePl;
-			StelUtils::rectToSphe(&ra, &de, XYZ);
-			StelUtils::rectToSphe(&raPl, &dePl, equPos);
-			const double distDegrees=StelLocation::distanceDegrees(raPl*M_180_PIf, dePl*M_180_PIf, ra*M_180_PIf, de*M_180_PIf);
+			const double distDegrees=equPos.angle(XYZ)*M_180_PI;
 			const double plRadiusDeg=planet->getAngularRadius(core);
-			const double sinDistCenter=distDegrees/plRadiusDeg; // 0...1
-			if (sinDistCenter<1.f)
+			const double sinDistCenter= distDegrees/plRadiusDeg; // should be 0...1, but 1 causes a flicker
+			if (sinDistCenter<0.9999)
 			{
-				const double angleDistCenterRad=asin(sinDistCenter); // 0..pi/2 on the lunar/planet sphere
+				const double angleDistCenterRad=asin(qMin(0.9999, sinDistCenter)); // 0..pi/2 on the lunar/planet sphere
 				const double aspectRatio=cos(angleDistCenterRad);
+				double ra, de, raPl, dePl;
+				StelUtils::rectToSphe(&ra, &de, XYZ);
+				StelUtils::rectToSphe(&raPl, &dePl, equPos);
 				const double angle=atan2(ra-raPl, de-dePl);
 				const double par = static_cast<double>(getParallacticAngle(core));
-				painter->drawEllipse(static_cast<float>(srcPos[0]), static_cast<float>(srcPos[1]), screenRadius, screenRadius*aspectRatio, angle-par );
+				painter->drawEllipse(srcPos[0], srcPos[1], screenRadius, screenRadius*qMax(0.0001,aspectRatio), angle-par );
 			}
 			//else
-			//	qWarning() << "Distance greater 1 encountered for crater " << englishName << "at " << longitude << "/" << latitude;
+			//	qWarning() << "Sine of Distance" << sinDistCenter << ">0.99975 encountered for crater " << englishName << "at " << longitude << "/" << latitude;
 		}
 		painter->drawText(static_cast<float>(srcPos[0]), static_cast<float>(srcPos[1]), nameI18n, 0, 5.f, 5.f, false);
 	}

src/core/modules/NomenclatureMgr.cpp

@@ -557,6 +557,7 @@ int NomenclatureMgr::getTerminatorMaxAltitude() const
 void NomenclatureMgr::setFlagOutlineCraters(bool b)
 {
 	NomenclatureItem::flagOutlineCraters = b;
+	conf->setValue("astro/flag_planets_nomenclature_outline_craters", b);
 	emit flagOutlineCratersChanged(b);
 }