Add Metalstorm-style cursor aim

Virtual stick cursor steered through the gun reticle, server-side virtual pilot
using measured control responses, client cursor/camera handling with look-ahead,
free look and scroll zoom.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YVREx3uo7nz1FEhzveWTUh

src/main/java/dev/lumareth/improvedAerodynamics/flight/AimBasis.java

@@ -0,0 +1,101 @@
+package dev.lumareth.improvedAerodynamics.flight;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.block.state.properties.DirectionProperty;
+import net.minecraft.world.level.block.state.properties.Property;
+
+/**
+ * The frame cursor aim steers in, in ship coordinates: forward is the boresight (what Warium's gun reticle points
+ * along, from the HUD block in front of the seat, else the way the seat faces), up is the ship's up axis and right
+ * completes it. Server and client both build it from the same block data, so a cursor sent as components in this
+ * frame means the same on both.
+ *
+ * @param nodePos the Vehicle Control Node the seat is linked to
+ */
+public record AimBasis(BlockPos seatPos, BlockPos nodePos, double[] forward, double[] right, double[] up) {
+
+    /**
+     * @param entityPos block position of the seat entity. Warium's control seat block is at that position or just
+     *                  below it.
+     * @return null if there is no seat block linked to a control node there
+     */
+    public static AimBasis of(Level level, BlockPos entityPos) {
+        for (BlockPos pos : new BlockPos[]{entityPos, entityPos.below()}) {
+            BlockEntity seat = level.getBlockEntity(pos);
+            if (seat == null || !seat.getPersistentData().contains("ControlX")) {
+                continue;
+            }
+            CompoundTag tag = seat.getPersistentData();
+            BlockPos nodePos = BlockPos.containing(tag.getDouble("ControlX"), tag.getDouble("ControlY"), tag.getDouble("ControlZ"));
+            return new AimBasis(pos, nodePos, null, null, null).withAxes(level, pos, nodePos);
+        }
+        return null;
+    }
+
+    private AimBasis withAxes(Level level, BlockPos seatPos, BlockPos nodePos) {
+        BlockState state = level.getBlockState(seatPos);
+        Direction facing = Direction.NORTH;
+        Property<?> property = state.getBlock().getStateDefinition().getProperty("facing");
+        if (property instanceof DirectionProperty directionProperty) {
+            facing = state.getValue(directionProperty);
+        }
+        double fx = facing.getStepX();
+        double fy = facing.getStepY();
+        double fz = facing.getStepZ();
+
+        // Warium's gun reticle: the HUD block in front of the seat holds the aim vector of its guns
+        BlockEntity hud = level.getBlockEntity(seatPos.relative(facing));
+        if (hud != null && hud.getPersistentData().contains("Pitch")) {
+            CompoundTag hudTag = hud.getPersistentData();
+            double bx = hudTag.getDouble("X") + facing.getStepX();
+            double by = hudTag.getDouble("Pitch");
+            double bz = hudTag.getDouble("Z") + facing.getStepZ();
+            if (bx * bx + by * by + bz * bz > 1.0E-6) {
+                fx = bx;
+                fy = by;
+                fz = bz;
+            }
+        }
+        double length = Math.sqrt(fx * fx + fy * fy + fz * fz);
+        if (length < 1.0E-6) {
+            fx = 0.0;
+            fy = 0.0;
+            fz = -1.0;
+            length = 1.0;
+        }
+        fx /= length;
+        fy /= length;
+        fz /= length;
+
+        // right = forward x up(0,1,0)
+        double rx = -fz;
+        double ry = 0.0;
+        double rz = fx;
+        double rl = Math.sqrt(rx * rx + rz * rz);
+        if (rl < 1.0E-6) {
+            rx = 1.0;
+            rz = 0.0;
+            rl = 1.0;
+        }
+        rx /= rl;
+        rz /= rl;
+        // up = right x forward
+        double ux = ry * fz - rz * fy;
+        double uy = rz * fx - rx * fz;
+        double uz = rx * fy - ry * fx;
+        return new AimBasis(seatPos, nodePos, new double[]{fx, fy, fz}, new double[]{rx, ry, rz}, new double[]{ux, uy, uz});
+    }
+
+    /** Ship-space direction of a cursor given by its components along forward, right and up. */
+    public double[] toShip(double cf, double cr, double cu) {
+        return new double[]{
+                forward[0] * cf + right[0] * cr + up[0] * cu,
+                forward[1] * cf + right[1] * cr + up[1] * cu,
+                forward[2] * cf + right[2] * cr + up[2] * cu};
+    }
+}