From 018e8a0444168d83e8070531bf79eb3edc37f472 Mon Sep 17 00:00:00 2001
From: Jonathan Westhues <jwesthues@cq.cx>
Date: Thu, 8 May 2008 00:12:23 -0800
Subject: [PATCH] Draw an additional projection line, when showing a point-line
 projected distance constraint.

[git-p4: depot-paths = "//depot/solvespace/": change = 1712]
---
 drawconstraint.cpp | 13 +++++++++++++
 dsc.h              |  1 +
 util.cpp           | 12 ++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/drawconstraint.cpp b/drawconstraint.cpp
index 0b9686a..0782724 100644
--- a/drawconstraint.cpp
+++ b/drawconstraint.cpp
@@ -151,6 +151,19 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
             LineDrawOrGetDistance(pt, closest);
             Vector ref = ((closest.Plus(pt)).ScaledBy(0.5)).Plus(disp.offset);
             DoLabel(ref, labelPos, gr, gu);
+
+            if(workplane.v != Entity::FREE_IN_3D.v) {
+                // Draw the projection marker from the closest point on the
+                // projected line to the projected point on the real line.
+                lAB = (lA.Minus(lB));
+                double t = (lA.Minus(closest)).DivPivoting(lAB);
+
+                Vector lA = SS.GetEntity(line->point[0])->PointGetNum();
+                Vector lB = SS.GetEntity(line->point[1])->PointGetNum();
+
+                Vector c2 = (lA.ScaledBy(1-t)).Plus(lB.ScaledBy(t));
+                DoProjectedPoint(&c2);
+            }
             break;
         }
 
diff --git a/dsc.h b/dsc.h
index 1da3023..b9441a5 100644
--- a/dsc.h
+++ b/dsc.h
@@ -48,6 +48,7 @@ public:
     Vector WithMagnitude(double s);
     Vector ScaledBy(double s);
     Vector ProjectInto(hEntity wrkpl);
+    double DivPivoting(Vector delta);
 };
 
 class Point2d {
diff --git a/util.cpp b/util.cpp
index abb6fd9..c311018 100644
--- a/util.cpp
+++ b/util.cpp
@@ -275,6 +275,18 @@ Vector Vector::ProjectInto(hEntity wrkpl) {
     return p0.Plus((u.ScaledBy(up)).Plus(v.ScaledBy(vp)));
 }
 
+double Vector::DivPivoting(Vector delta) {
+    double m = max(fabs(delta.x), max(fabs(delta.y), fabs(delta.z)));
+
+    if(m == fabs(delta.x)) {
+        return x/delta.x;
+    } else if(m == fabs(delta.y)) {
+        return y/delta.y;
+    } else if(m == fabs(delta.z)) {
+        return z/delta.z;
+    } else oops();
+}
+
 Point2d Point2d::Plus(Point2d b) {
     Point2d r;
     r.x = x + b.x;