draw beam wider at the source than at the target

src/ui/GameWorldView.cpp

@@ -15,11 +15,13 @@
 #include <QDir>
 #include <QFont>
 #include <QKeyEvent>
+#include <QLinearGradient>
 #include <QMessageBox>
 #include <QMouseEvent>
 #include <QPainter>
 #include <QPen>
 #include <QPolygonF>
+#include <QRadialGradient>
 #include <QRegion>
 #include <QStringList>
 #include <QTimer>
@@ -1487,6 +1489,10 @@ void GameWorldView::drawDebugOverlay(QPainter& painter)
 
 void GameWorldView::drawBeams(QPainter& painter)
 {
+    const Tick now = m_sim->currentTick();
+    const QPainter::RenderHints savedHints = painter.renderHints();
+    painter.setRenderHint(QPainter::Antialiasing, true);
+
     for (const ActiveBeam& beam : m_activeBeams)
     {
         const std::optional<QVector2D> shooterPos = entityPosition(beam.event.shooter);
@@ -1500,10 +1506,61 @@ void GameWorldView::drawBeams(QPainter& painter)
             case BeamKind::Repair:  color = m_visuals->beams.repairColor;  break;
             case BeamKind::Salvage: color = m_visuals->beams.salvageColor; break;
         }
-        painter.setPen(QPen(color, m_visuals->beams.widthPx));
-        painter.drawLine(worldToWidget(*shooterPos),
-                         worldToWidget(*targetPos + beam.targetOffset));
+
+        const QPointF s = worldToWidget(*shooterPos);
+        const QPointF t = worldToWidget(*targetPos + beam.targetOffset);
+
+        // Unit direction/perpendicular of the beam in widget space. A degenerate
+        // zero-length beam (shooter and target coincide) has no direction to
+        // taper along, so skip it.
+        const QVector2D delta(static_cast<float>(t.x() - s.x()),
+                              static_cast<float>(t.y() - s.y()));
+        const float lengthPx = delta.length();
+        if (lengthPx < 0.001f) { continue; }
+        const QVector2D dir  = delta / lengthPx;
+        const QVector2D perp(-dir.y(), dir.x());
+
+        // Age of this beam as a fraction of its lifetime, in [0, 1]. Drives the
+        // muzzle-flash pulse below (strongest at the instant of firing).
+        const float ageFrac = std::min(1.0f,
+            static_cast<float>(now - beam.event.emittedAt)
+                / static_cast<float>(kBeamLifetimeTicks));
+
+        // Directional taper: draw the beam as a quad that is wide at the shooter
+        // and narrows to a faint tip at the target, so it reads as an arrow
+        // pointing away from whoever fired it. Without this, a beam strung
+        // between two nearby ships is symmetric and gives no cue which end is the
+        // source (the readability problem this addresses).
+        const float widthPx  = std::max(1.0f, static_cast<float>(m_visuals->beams.widthPx));
+        const float baseHalf = widthPx * 1.f;
+        const float tipHalf  = widthPx * 0.35f;
+
+        QPolygonF quad;
+        quad << QPointF(s.x() + static_cast<qreal>(perp.x() * baseHalf),
+                        s.y() + static_cast<qreal>(perp.y() * baseHalf))
+             << QPointF(s.x() - static_cast<qreal>(perp.x() * baseHalf),
+                        s.y() - static_cast<qreal>(perp.y() * baseHalf))
+             << QPointF(t.x() - static_cast<qreal>(perp.x() * tipHalf),
+                        t.y() - static_cast<qreal>(perp.y() * tipHalf))
+             << QPointF(t.x() + static_cast<qreal>(perp.x() * tipHalf),
+                        t.y() + static_cast<qreal>(perp.y() * tipHalf));
+
+        QColor bright = color.lighter(160);
+        bright.setAlpha(255);
+        QColor faint = color;
+        faint.setAlpha(90);
+
+        QLinearGradient bodyGrad(s, t);
+        bodyGrad.setColorAt(0.0, bright);
+        bodyGrad.setColorAt(1.0, faint);
+
+        painter.setPen(Qt::NoPen);
+        painter.setBrush(bodyGrad);
+        painter.drawPolygon(quad);
     }
+
+    painter.setBrush(Qt::NoBrush);
+    painter.setRenderHints(savedHints);
 }
 
 void GameWorldView::drawOverlays(QPainter& painter)