From 7ac2021bfe0d3032e161520e3fa790ef621e39b3 Mon Sep 17 00:00:00 2001
From: Shamus Hammons <jlhamm@acm.org>
Date: Fri, 16 Sep 2011 21:21:18 +0000
Subject: [PATCH] Added 'Fixed Angle' functionality to Line.

---
 README       |  4 ++--
 src/line.cpp | 29 +++++++++++++++++++++++++++--
 src/line.h   |  1 +
 3 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/README b/README
index dec1d80..e749f3f 100644
--- a/README
+++ b/README
@@ -70,8 +70,8 @@ love to hear from you so that we can improve!
 
 @-~ Installation ~-@
 
-Architektonas is built on the Qt 4 framework; it requires version 4.7.1 or
-later. We build it using gcc v4.4.5; we can't guarantee that it will compile on
+Architektonas is built on the Qt 4 framework; it requires version 4.7.4 or
+later. We build it using gcc v4.4.6; we can't guarantee that it will compile on
 lesser versions but you never know. Building Architektonas should be as easy as
 typing:
 
diff --git a/src/line.cpp b/src/line.cpp
index 60e5ab0..d6169d6 100644
--- a/src/line.cpp
+++ b/src/line.cpp
@@ -23,7 +23,8 @@
 
 Line::Line(Vector p1, Vector p2, Object * p/*= NULL*/): Object(p1, p), endpoint(p2),
 	draggingLine(false), draggingHandle1(false), draggingHandle2(false), //needUpdate(false),
-	length(Vector::Magnitude(p2, p1)), hitPoint1(false), hitPoint2(false), hitLine(false)
+	length(Vector::Magnitude(p2, p1)), angle(Vector(endpoint - position).Unit()),
+	hitPoint1(false), hitPoint2(false), hitLine(false)
 {
 }
 
@@ -97,7 +98,7 @@ We solve this by allowing only *one* Dimension object to be attached to the Line
 Arc, etc. and by giving the Dimension object a pointer to our endpoints.
 
 Problem still arises when we delete this object; The attached Dimension object will
-then have bad pointers! What is *should* do is delete the object if and only if this
+then have bad pointers! What it *should* do is delete the object if and only if this
 line is not attached to any other object. If it is, then one of those attachment
 points should be sent to the dimension object (done for position & endpoint).
 
@@ -257,6 +258,7 @@ software currently out there: the GUI will try to do the right thing, most of th
 		Vector point1 = (draggingHandle1 ? endpoint : position);
 		Vector point2 = (draggingHandle1 ? position : endpoint);
 
+#if 0
 		Vector current(point2, point1);
 		Vector v = current.Unit() * length;
 		Vector v2 = point1 + v;
@@ -264,6 +266,22 @@ software currently out there: the GUI will try to do the right thing, most of th
 		//bleh
 		if (!Object::fixedLength)
 			v2 = point2;
+#endif
+
+		if (Object::fixedAngle)
+		{
+			// Here we calculate the component of the current vector along the fixed angle.
+			// A_compB = (A . Bu) * Bu
+			double magnitudeAlongB = Vector::Dot(Vector(point2 - point1), angle);
+
+			if (draggingHandle1)
+				position = endpoint + (angle * magnitudeAlongB);
+
+			if (draggingHandle2)
+				endpoint = position + (angle * magnitudeAlongB);
+		}
+//		else
+//			v2 = point2;
 
 //If we tell the dimension to flip sides, this is no longer a valid
 //assumption. !!! FIX !!!
@@ -307,6 +325,13 @@ software currently out there: the GUI will try to do the right thing, most of th
 			// it turns out to have a fixed length. :-)
 			length = Vector(endpoint - position).Magnitude();
 		}
+
+		if (!Object::fixedAngle)
+		{
+			// Calculate the new angle, just in case on the next move it turns out to
+			// be fixed. :-)
+			angle = Vector(endpoint - position).Unit();
+		}
 	}
 
 	draggingLine = false;
diff --git a/src/line.h b/src/line.h
index 8fd1ed9..ab26225 100644
--- a/src/line.h
+++ b/src/line.h
@@ -35,6 +35,7 @@ class Line: public Object
 		bool draggingHandle2;
 		bool objectWasDragged;
 		double length;
+		Vector angle;
 		bool hitPoint1, hitPoint2, hitLine;
 		bool oldHitPoint1, oldHitPoint2, oldHitLine;
 };
-- 
2.37.2