Add Vector Projection Expression (SkriptLang#5482)

add vector projection expression

Co-authored-by: LimeGlass <16087552+TheLimeGlass@users.noreply.github.com>

src/main/java/ch/njol/skript/expressions/ExprVectorProjection.java

@@ -0,0 +1,81 @@
+/**
+ *   This file is part of Skript.
+ *
+ *  Skript is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Skript is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with Skript.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright Peter Güttinger, SkriptLang team and contributors
+ */
+package ch.njol.skript.expressions;
+
+import ch.njol.skript.Skript;
+import ch.njol.skript.doc.Description;
+import ch.njol.skript.doc.Examples;
+import ch.njol.skript.doc.Name;
+import ch.njol.skript.doc.Since;
+import ch.njol.skript.lang.Expression;
+import ch.njol.skript.lang.ExpressionType;
+import ch.njol.skript.lang.SkriptParser.ParseResult;
+import ch.njol.skript.lang.util.SimpleExpression;
+import ch.njol.util.Kleenean;
+import org.bukkit.event.Event;
+import org.bukkit.util.Vector;
+import org.eclipse.jdt.annotation.Nullable;
+
+@Name("Vectors - Vector Projection")
+@Description("An expression to get the vector projection of two vectors.")
+@Examples("set {_projection} to vector projection of vector(1, 2, 3) onto vector(4, 4, 4)")
+@Since("INSERT VERSION")
+public class ExprVectorProjection extends SimpleExpression<Vector> {
+
+	static {
+		Skript.registerExpression(ExprVectorProjection.class, Vector.class, ExpressionType.COMBINED, "[vector] projection [of] %vector% on[to] %vector%");
+	}
+
+	private Expression<Vector> left, right;
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public boolean init(Expression<?>[] exprs, int matchedPattern, Kleenean isDelayed, ParseResult parseResult) {
+		this.left = (Expression<Vector>) exprs[0];
+		this.right = (Expression<Vector>) exprs[1];
+		return true;
+	}
+
+	@Override
+	@Nullable
+	protected Vector[] get(Event event) {
+		Vector left = this.left.getOptionalSingle(event).orElse(new Vector());
+		Vector right = this.right.getOptionalSingle(event).orElse(new Vector());
+		double dot = left.dot(right);
+		double length = right.lengthSquared();
+		double scalar = dot / length;
+		return new Vector[] {right.clone().multiply(scalar)};
+	}
+
+	@Override
+	public boolean isSingle() {
+		return true;
+	}
+
+	@Override
+	public Class<? extends Vector> getReturnType() {
+		return Vector.class;
+	}
+
+	@Override
+	public String toString(@Nullable Event event, boolean debug) {
+		return "vector projection of " + left.toString(event, debug) + " onto " + right.toString(event, debug);
+	}
+
+}