Mercurial > ldforge / file diff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/geometry/plane.cpp	Wed May 30 22:31:06 2018 +0300
@@ -0,0 +1,73 @@
+/*
+ *  LDForge: LDraw parts authoring CAD
+ *  Copyright (C) 2013 - 2018 Teemu Piippo
+ *
+ *  This program 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.
+ *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "plane.h"
+
+/*
+ * Constructs a plane from three points
+ */
+Plane Plane::fromPoints(const Vertex& v1, const Vertex& v2, const Vertex& v3)
+{
+	Plane result;
+	result.normal = QVector3D::crossProduct(v2 - v1, v3 - v1);
+	result.point = v1;
+	return result;
+}
+
+/*
+ * Returns whether or not this plane is valid.
+ */
+bool Plane::isValid() const
+{
+	return not normal.isNull();
+}
+
+/*
+ * Finds the intersection of a line and a plane. Returns a structure containing whether or not
+ * there was an intersection as well as the intersected vertex if there was one. Can return a point
+ * outside of the line segment.
+ *
+ * C.f. https://en.wikipedia.org/wiki/Line%E2%80%93plane_intersection#Algebraic_form
+ */
+Plane::IntersectionResult Plane::intersection(const Line& line) const
+{
+	if (isValid())
+	{
+		QVector3D lineVector = line.v_2 - line.v_1;
+		qreal dot = QVector3D::dotProduct(lineVector, normal);
+
+		if (not qFuzzyCompare(dot, 0.0))
+		{
+			qreal factor = QVector3D::dotProduct(point - line.v_1, normal) / dot;
+			IntersectionResult result;
+			result.intersected = true;
+			result.vertex = Vertex::fromVector(lineVector * factor + (line.v_1 - Vertex {0, 0, 0}));
+			return result;
+		}
+		else
+		{
+			// did not intersect
+			return {};
+		}
+	}
+	else
+	{
+		// plane is invalid
+		return {};
+	}
+}