Voltmeter

src/main/java/de/ph87/electro/CONFIG.java

@@ -6,6 +6,10 @@ import static java.lang.Math.round;
 
 public class CONFIG {
 
+  public static final double NO_RESISTANCE = 1e-12;
+
+  public static final double MAX_RESISTANCE = 1 / NO_RESISTANCE;
+
   public static boolean SHOW_WIRE_DETAILS = true;
 
   public static boolean SHOW_JUNCTION_VOLTAGES = false;

src/main/java/de/ph87/electro/circuit/Circuit.java

@@ -5,6 +5,9 @@ import de.ph87.electro.circuit.part.Part;
 import de.ph87.electro.circuit.part.PartDto;
 import de.ph87.electro.circuit.part.Position;
 import de.ph87.electro.circuit.part.junction.Junction;
+import de.ph87.electro.circuit.part.parts.Battery;
+import de.ph87.electro.circuit.part.parts.Poti;
+import de.ph87.electro.circuit.part.parts.Voltmeter;
 import de.ph87.electro.circuit.wire.Wire;
 import de.ph87.electro.circuit.wire.WireDto;
 import lombok.Getter;
@@ -19,6 +22,8 @@ import java.util.List;
 import java.util.Optional;
 import java.util.stream.Stream;
 
+import static de.ph87.electro.circuit.part.Position.RST;
+
 public class Circuit {
 
   @Getter
@@ -40,7 +45,7 @@ public class Circuit {
   public Circuit(final File file, final CircuitDto dto) {
     created = dto.getCreated();
     for (PartDto partDto : dto.getParts()) {
-      final Part part = Part.of(this, partDto);
+      final Part part = Part.fromDto(this, partDto);
       verifyFree(part.getPosition());
       parts.add(part);
     }

src/main/java/de/ph87/electro/circuit/CircuitPanelDropTarget.java

@@ -37,6 +37,8 @@ public class CircuitPanelDropTarget extends AbstractDropTarget {
       circuitPanel.getCircuit().addPart(new SwitchCross(circuitPanel.getCircuit(), position));
     } else if (data.equals(Poti.class.getSimpleName())) {
       circuitPanel.getCircuit().addPart(new Poti(circuitPanel.getCircuit(), position));
+    } else if (data.equals(Voltmeter.class.getSimpleName())) {
+      circuitPanel.getCircuit().addPart(new Voltmeter(circuitPanel.getCircuit(), position));
     } else {
       throw new RuntimeException();
     }

src/main/java/de/ph87/electro/circuit/calculation/Calculation.java

@@ -1,5 +1,6 @@
 package de.ph87.electro.circuit.calculation;
 
+import de.ph87.electro.CONFIG;
 import de.ph87.electro.circuit.Circuit;
 import de.ph87.electro.circuit.part.InnerConnection;
 import de.ph87.electro.circuit.part.Part;
@@ -22,10 +23,6 @@ import static java.lang.Math.max;
 @Getter
 public class Calculation {
 
-  public static final double NO_RESISTANCE = 1e-12;
-
-  private static final double FULL_ADMITTANCE = 1 / NO_RESISTANCE;
-
   private final List<Junction> junctions = new ArrayList<>();
 
   private final Set<Part> parts = new HashSet<>();
@@ -76,7 +73,7 @@ public class Calculation {
 
   private void fromSchematic() {
     wires.forEach(
-      wire -> addResistor(wire.getA(), wire.getB(), NO_RESISTANCE)
+      wire -> addResistor(wire.getA(), wire.getB(), CONFIG.NO_RESISTANCE)
     );
     parts.forEach(part -> {
       for (final InnerConnection innerConnection : part.getInnerConnections()) {
@@ -113,7 +110,7 @@ public class Calculation {
   private double getCurrent(final Wire wire) {
     final int indexA = getJunctionIndex(wire.getA());
     final int indexB = getJunctionIndex(wire.getB());
-    final double conductance = indexA >= 0 && indexB >= 0 ? matrix.getEntry(indexA, indexB) : FULL_ADMITTANCE;
+    final double conductance = indexA >= 0 && indexB >= 0 ? matrix.getEntry(indexA, indexB) : 1 / CONFIG.NO_RESISTANCE;
     final double potentialDifference = getPotential(wire.getB()) - getPotential(wire.getA());
     return conductance * potentialDifference;
   }

src/main/java/de/ph87/electro/circuit/part/Part.java

@@ -80,7 +80,7 @@ public abstract class Part {
     evaluate();
   }
 
-  public void render() {
+  public final void render() {
     render.rect(ZERO, RASTER, RASTER, null, null, PART_BACKGROUND);
 
     _labels();
@@ -136,7 +136,7 @@ public abstract class Part {
     return Collections.emptyList();
   }
 
-  public static Part of(final Circuit circuit, final PartDto abstractDto) {
+  public static Part fromDto(final Circuit circuit, final PartDto abstractDto) {
     return switch (abstractDto) {
       case final BatteryDto dto -> new Battery(circuit, dto);
       case final ConnectorCornerDto dto -> new ConnectorCorner(circuit, dto);
@@ -146,6 +146,8 @@ public abstract class Part {
       case final Switch1x1Dto dto -> new Switch1x1(circuit, dto);
       case final Switch1x2Dto dto -> new Switch1x2(circuit, dto);
       case final SwitchCrossDto dto -> new SwitchCross(circuit, dto);
+      case final PotiDto dto -> new Poti(circuit, dto);
+      case final VoltmeterDto dto -> new Voltmeter(circuit, dto);
       case null, default -> throw new RuntimeException();
     };
   }

src/main/java/de/ph87/electro/circuit/part/PartDto.java

@@ -40,6 +40,7 @@ public abstract class PartDto {
       case final Switch1x2 part -> new Switch1x2Dto(part);
       case final SwitchCross part -> new SwitchCrossDto(part);
       case final Poti part -> new PotiDto(part);
+      case final Voltmeter part -> new VoltmeterDto(part);
       case null, default -> throw new RuntimeException();
     };
   }

src/main/java/de/ph87/electro/circuit/part/Position.java

@@ -2,6 +2,7 @@ package de.ph87.electro.circuit.part;
 
 import lombok.Getter;
 import lombok.ToString;
+import org.apache.commons.math3.linear.RealVector;
 
 import java.awt.*;
 import java.awt.event.MouseEvent;
@@ -22,6 +23,10 @@ public final class Position {
 
   public final Point raster;
 
+  public static Position ABS(final RealVector vector) {
+    return ABS(vector.getEntry(0), vector.getEntry(1));
+  }
+
   public static Position ABS(final double absoluteX, final double absoluteY) {
     return new Position((int) round(absoluteX), (int) round(absoluteY));
   }

src/main/java/de/ph87/electro/circuit/part/Render.java

@@ -19,11 +19,11 @@ public class Render {
 
   private final Graphics2D g = image.createGraphics();
 
-  public void line(final Junction junction0, final Junction junction1, final Color color, final BasicStroke stroke) {
+  public void line(final Junction junction0, final Junction junction1, final Color color, final Stroke stroke) {
     line(junction0.getPosition(), junction1.getPosition(), color, stroke);
   }
 
-  public void line(final Position p0, final Position p1, final Color color, final BasicStroke stroke) {
+  public void line(final Position p0, final Position p1, final Color color, final Stroke stroke) {
     if (color != null) {
       g.setColor(color);
     }

src/main/java/de/ph87/electro/circuit/part/parts/Poti.java

@@ -13,7 +13,6 @@ import java.awt.*;
 import java.util.List;
 
 import static de.ph87.electro.CONFIG.*;
-import static de.ph87.electro.circuit.calculation.Calculation.NO_RESISTANCE;
 import static java.lang.Math.max;
 
 @Getter
@@ -38,7 +37,7 @@ public class Poti extends Part {
     end = addJunction("E", P90, P50);
   }
 
-  protected Poti(final Circuit circuit, final PotiDto dto) {
+  public Poti(final Circuit circuit, final PotiDto dto) {
     super(circuit, dto);
     common = addJunction(dto.getCommon().getName(), P10, P50);
     middle = addJunction(dto.getMiddle().getName(), P50, P10);

src/main/java/de/ph87/electro/circuit/part/parts/RotationMatrix.java

@@ -0,0 +1,23 @@
+package de.ph87.electro.circuit.part.parts;
+
+import org.apache.commons.math3.linear.Array2DRowRealMatrix;
+import org.apache.commons.math3.linear.RealMatrix;
+
+import static java.lang.Math.cos;
+import static java.lang.Math.sin;
+
+public class RotationMatrix extends Array2DRowRealMatrix {
+
+  public static RealMatrix ofDegrees(final double degrees) {
+    final double radians = degrees * Math.PI / 180.0;
+    return new RotationMatrix(radians);
+  }
+
+  private RotationMatrix(final double radians) {
+    super(new double[][]{
+      {cos(radians), -sin(radians)},
+      {sin(radians), cos(radians)},
+    });
+  }
+
+}

src/main/java/de/ph87/electro/circuit/part/parts/Switch1x1.java

@@ -12,7 +12,7 @@ import java.awt.*;
 import java.util.List;
 
 import static de.ph87.electro.CONFIG.*;
-import static de.ph87.electro.circuit.calculation.Calculation.NO_RESISTANCE;
+import static de.ph87.electro.CONFIG.NO_RESISTANCE;
 
 @Getter
 @ToString(callSuper = true)

src/main/java/de/ph87/electro/circuit/part/parts/Switch1x2.java

@@ -11,7 +11,7 @@ import lombok.ToString;
 import java.util.List;
 
 import static de.ph87.electro.CONFIG.*;
-import static de.ph87.electro.circuit.calculation.Calculation.NO_RESISTANCE;
+import static de.ph87.electro.CONFIG.NO_RESISTANCE;
 
 @Getter
 @ToString(callSuper = true)

src/main/java/de/ph87/electro/circuit/part/parts/SwitchCross.java

@@ -11,7 +11,7 @@ import lombok.ToString;
 import java.util.List;
 
 import static de.ph87.electro.CONFIG.*;
-import static de.ph87.electro.circuit.calculation.Calculation.NO_RESISTANCE;
+import static de.ph87.electro.CONFIG.NO_RESISTANCE;
 
 @Getter
 @ToString(callSuper = true)

src/main/java/de/ph87/electro/circuit/part/parts/Voltmeter.java

@@ -0,0 +1,95 @@
+package de.ph87.electro.circuit.part.parts;
+
+import de.ph87.electro.circuit.Circuit;
+import de.ph87.electro.circuit.part.InnerConnection;
+import de.ph87.electro.circuit.part.Part;
+import de.ph87.electro.circuit.part.PartDto;
+import de.ph87.electro.circuit.part.Position;
+import de.ph87.electro.circuit.part.junction.Junction;
+import lombok.Getter;
+import org.apache.commons.math3.linear.ArrayRealVector;
+import org.apache.commons.math3.linear.RealMatrix;
+import org.apache.commons.math3.linear.RealVector;
+
+import java.awt.*;
+import java.util.List;
+
+import static de.ph87.electro.CONFIG.*;
+import static de.ph87.electro.circuit.part.Position.ABS;
+
+@Getter
+public class Voltmeter extends Part {
+
+  private static final RealVector ANCHOR = new ArrayRealVector(new double[]{P50, P50});
+
+  private static final RealVector FINGER = new ArrayRealVector(new double[]{P90, P50}).subtract(ANCHOR);
+
+  private static final Stroke SCALE_STROKE = new BasicStroke(1);
+
+  private static final double DEGREES_TOTAL = 90.0;
+
+  private static final double DEGREES_ROTATE = -135.0;
+
+  private final Junction a;
+
+  private final Junction b;
+
+  private double min = -3;
+
+  private double max = +3;
+
+  private double voltage;
+
+  private RealVector tip;
+
+  public Voltmeter(final Circuit circuit, final Position position) {
+    super(circuit, "Voltmeter", position);
+    a = addJunction("A", P10, P50);
+    b = addJunction("B", P90, P50);
+    postCalculate(); // TODO remove
+  }
+
+  public Voltmeter(final Circuit circuit, final PartDto dto) {
+    super(circuit, dto);
+    a = addJunction("A", P10, P50);
+    b = addJunction("B", P90, P50);
+    postCalculate(); // TODO remove
+  }
+
+  public void setMin(final double min) {
+    this.min = min;
+    evaluate();
+  }
+
+  public void setMax(final double max) {
+    this.max = max;
+    evaluate();
+  }
+
+  @Override
+  public void postCalculate() {
+    voltage = !Double.isNaN(b.getVoltage()) && !Double.isNaN(a.getVoltage()) ? b.getVoltage() - a.getVoltage() : 0.0;
+    final double ratio = (voltage - min) / (max - min);
+    final double degrees = DEGREES_TOTAL * ratio + DEGREES_ROTATE;
+    final RealMatrix rotate = RotationMatrix.ofDegrees(degrees);
+    final RealVector rotatedFinger = rotate.operate(FINGER);
+    tip = ANCHOR.add(rotatedFinger);
+  }
+
+  @Override
+  public void _render() {
+    render.clockwise(getOrientation());
+    render.line(ABS(ANCHOR), ABS(tip), Color.BLACK, SCALE_STROKE);
+  }
+
+  @Override
+  protected void _labels() {
+    render.textCenter(LABEL_FONT, "%.2f V".formatted(voltage), P50, P75, Color.BLACK);
+  }
+
+  @Override
+  public List<InnerConnection> getInnerConnections() {
+    return List.of(new InnerConnection(a, b, MAX_RESISTANCE));
+  }
+
+}

src/main/java/de/ph87/electro/circuit/part/parts/VoltmeterDto.java

@@ -0,0 +1,32 @@
+package de.ph87.electro.circuit.part.parts;
+
+import de.ph87.electro.circuit.part.PartDto;
+import de.ph87.electro.circuit.part.junction.JunctionDto;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+import lombok.ToString;
+
+@Getter
+@ToString
+@NoArgsConstructor
+public class VoltmeterDto extends PartDto {
+
+  private JunctionDto a;
+
+  private JunctionDto b;
+
+  @Setter
+  private double min;
+
+  @Setter
+  private double max;
+
+  public VoltmeterDto(final Voltmeter voltmeter) {
+    a = new JunctionDto(voltmeter.getA());
+    b = new JunctionDto(voltmeter.getB());
+    min = voltmeter.getMin();
+    max = voltmeter.getMax();
+  }
+
+}

src/main/java/de/ph87/electro/sidebar/Sidebar.java

@@ -44,6 +44,7 @@ public class Sidebar extends JPanel {
     addPart(new Switch1x2(null, Position.ZERO));
     addPart(new SwitchCross(null, Position.ZERO));
     addPart(new Poti(null, Position.ZERO));
+    addPart(new Voltmeter(null, Position.ZERO));
   }
 
   @SuppressWarnings("UnusedReturnValue")