1 // line.cpp: Line object
3 // Part of the Architektonas Project
4 // (C) 2011 Underground Software
5 // See the README and GPLv3 files for licensing and warranty information
7 // JLH = James L. Hammons <jlhamm@acm.org>
10 // --- ---------- ------------------------------------------------------------
11 // JLH 03/22/2011 Created this file
12 // JLH 04/11/2011 Fixed attached dimensions to stay at correct length when
13 // "Fixed Length" button is down
14 // JLH 04/27/2011 Fixed attached dimension to stay a correct length when
15 // "Fixed Length" button is *not* down ;-)
16 // JLH 05/29/2011 Added (some) mouseover hints
22 #include "dimension.h"
26 Line::Line(Vector p1, Vector p2, Object * p/*= NULL*/): Object(p1, p), endpoint(p2),
27 draggingLine(false), draggingHandle1(false), draggingHandle2(false), //needUpdate(false),
28 length(Vector::Magnitude(p2, p1)), angle(Vector(endpoint - position).Unit()),
29 hitPoint1(false), hitPoint2(false), hitLine(false)
35 // If there are any attached Dimensions, we must set the attachment points
36 // to NULL since they will no longer be valid.
37 if (attachedDimension)
39 attachedDimension->SetPoint1(NULL);
40 attachedDimension->SetPoint2(NULL);
42 // IT WOULD BE NICE to have any object points attached to this line automagically
43 // connect to this dimension object at this point, instead of just becoming
47 /*virtual*/ void Line::Draw(Painter * painter)
49 painter->SetPen(QPen(Qt::red, 2.0, Qt::DotLine));
51 if ((state == OSSelected) || ((state == OSInactive) && hitPoint1))
52 painter->DrawEllipse(position, 4.0, 4.0);
54 if ((state == OSSelected) || ((state == OSInactive) && hitPoint2))
55 painter->DrawEllipse(endpoint, 4.0, 4.0);
57 if ((state == OSInactive) && !hitLine)
58 painter->SetPen(QPen(Qt::black, 1.0, Qt::SolidLine));
60 if (Object::fixedLength && (draggingHandle1 || draggingHandle2))
62 Vector point1 = (draggingHandle1 ? endpoint : position);
63 Vector point2 = (draggingHandle1 ? position : endpoint);
65 Vector current(point2 - point1);
66 Vector v = current.Unit() * length;
67 Vector v2 = point1 + v;
68 painter->DrawLine((int)point1.x, (int)point1.y, (int)v2.x, (int)v2.y);
70 if (current.Magnitude() > length)
72 painter->SetPen(QPen(QColor(128, 0, 0), 1.0, Qt::DashLine));
73 painter->DrawLine((int)v2.x, (int)v2.y, (int)point2.x, (int)point2.y);
77 painter->DrawLine((int)position.x, (int)position.y, (int)endpoint.x, (int)endpoint.y);
80 /*virtual*/ Vector Line::Center(void)
82 // Technically, this is the midpoint but who are we to quibble? :-)
83 Vector v((position.x - endpoint.x) / 2.0, (position.y - endpoint.y) / 2.0);
87 /*virtual*/ bool Line::Collided(Vector point)
89 // We can assume this, since this is a mouse down event here.
90 objectWasDragged = false;
94 There's a small problem here with the implementation: You can have a dimension tied
95 to only one point while at the same time you can have a dimension sitting on this line.
96 Since there's only *one* dimPoint for each point, this can be problematic...
98 We solve this by allowing only *one* Dimension object to be attached to the Line,
99 Arc, etc. and by giving the Dimension object a pointer to our endpoints.
101 Problem still arises when we delete this object; The attached Dimension object will
102 then have bad pointers! What it *should* do is delete the object if and only if this
103 line is not attached to any other object. If it is, then one of those attachment
104 points should be sent to the dimension object (done for position & endpoint).
106 NOTE: The STL vector<T> *does not* take ownership of pointers, therefore is suitable
109 Also: It would be nice to have a preview of the dimension being drawn, with a modifier
110 key to make it draw/show on the other side...
112 TODO: Make Dimension preview with modifier keys for showing on other side
114 // Is the dimension tool active? Let's use it:
117 // User clicked on the line itself (endpoint checks should preceed this one):
118 // (Priorities are taken care of in HitTest()...)
121 if (attachedDimension == NULL)
123 // How to get this object into the top level container???
125 The real question is do we care. I think so, because if this isn't in the top
126 level container, it won't get drawn...
127 But we can fix that by making this object call any attached object's (like
128 a dimension only) Draw() function... :-/
130 attachedDimension = new Dimension(&position, &endpoint, this);
133 parent->Add(attachedDimension);
137 // If there's one already there, tell it to flip sides...
138 attachedDimension->FlipSides();
146 if (state == OSInactive)
148 //printf("Line: pp = %lf, length = %lf, distance = %lf\n", parameterizedPoint, lineSegment.Magnitude(), distance);
149 //printf(" v1.Magnitude = %lf, v2.Magnitude = %lf\n", v1.Magnitude(), v2.Magnitude());
150 //printf(" point = %lf,%lf,%lf; p1 = %lf,%lf,%lf; p2 = %lf,%lf,%lf\n", point.x, point.y, point.z, position.x, position.y, position.z, endpoint.x, endpoint.y, endpoint.z);
152 //How to translate this into pixels from Document space???
153 //Maybe we need to pass a scaling factor in here from the caller? That would make sense, as
154 //the caller knows about the zoom factor and all that good kinda crap
155 //I think what's needed is an Object class variable/method that can be changed by the TLC and
156 //called in derived classes to properly scale the location to the current zoom level. That *should* work.
158 // ALSO: Need to code a global (read: Object class) variable that tells use whether a modifier
159 // key was pressed in addition to the mouse click, so we can do stuff like, say, hold
160 // down CTRL and be able to do multiple selecting of objects (in that case, we would
161 // keep the Object state from changing).
166 oldPoint = position; //maybe "position"?
167 draggingHandle1 = true;
174 oldPoint = endpoint; //maybe "position"?
175 draggingHandle2 = true;
187 else if (state == OSSelected)
189 // Here we test for collision with handles as well! (SOON!) [I think it works...NOPE]
192 if (v1.Magnitude() < 2.0) // Handle #1
193 else if (v2.Magnitude() < 2.0) // Handle #2
198 // state = OSInactive;
205 // If we got here, we clicked on nothing, so set the object to inactive.
206 // (Once we can read key modifiers, we can override this to allow multiple selection.)
211 /*virtual*/ void Line::PointerMoved(Vector point)
213 // Hit test tells us what we hit (if anything) through boolean variables. It
214 // also tells us whether or not the state changed.
215 needUpdate = HitTest(point);
217 objectWasDragged = (draggingLine | draggingHandle1 | draggingHandle2);
219 if (objectWasDragged)
221 Vector delta = point - oldPoint;
223 if (draggingHandle1 || draggingLine)
226 if (draggingHandle2 || draggingLine)
234 We can't count on any coupling between the dimension object and us, so how do we do this???
235 Also, there may be more than one Dimension object connected to a single endpoint!
238 - Keep track of the state of the connected dimension
239 - Pass the Dimension the point that's being changed and the delta
242 - Pass the point in a notification function (how?)
243 - Pass the point as a reference to the class instance object (&endpoint). This way, the line
244 doesn't have to care about keeping track of Dimensions connected to it. But still have to
245 care about other connected entities (other Lines, Circles, Arcs, Splines, Texts, etc). I
246 think I'd be OK with this.
247 Since the Dimension has a pointer to our object, all we have to do is update our coordinates
248 and the Dimension object will adjust itself on the next repaint. Problem solved, and we don't
249 have to know anything about how many Dimensions are connected to us, or where! \o/
250 The question then becomes, how do we do this kind of coupling???
252 We need to know about connected entities so that we can have them either move in expected ways
253 or constrain the movement of this Line object. This is how we will be a cut above all other CAD
254 software currently out there: the GUI will try to do the right thing, most of the time. :-)
258 // should only do this if "Fixed Length" is set... !!! FIX !!! [DONE]
259 Vector point1 = (draggingHandle1 ? endpoint : position);
260 Vector point2 = (draggingHandle1 ? position : endpoint);
263 Vector current(point2, point1);
264 Vector v = current.Unit() * length;
265 Vector v2 = point1 + v;
268 if (!Object::fixedLength)
272 if (Object::fixedAngle)
274 // Here we calculate the component of the current vector along the fixed angle.
275 // A_compB = (A . Bu) * Bu
276 double magnitudeAlongB = Vector::Dot(Vector(point2 - point1), angle);
278 Actually, this isn't quite right. What we want to do is look for the intersection along either
279 the horizontal line or vertical line that intersects from the current mouse position.
283 position = endpoint + (angle * magnitudeAlongB);
286 endpoint = position + (angle * magnitudeAlongB);
291 //If we tell the dimension to flip sides, this is no longer a valid
292 //assumption. !!! FIX !!!
293 //Ideally, we should just send the point that's changing to the Dimension object
294 //and have it figure out which point needs to move... Or is it???
295 // Ideally, we shouldn't have to fuck around with this shit. We need to fix the rendering code
296 // so that we don't have to wait until the dragging is done to correct the position of the
297 // point in question, but we'd need another variable tho.
300 dimPoint1->SetPoint1(draggingHandle1 ? v2 : position);
303 dimPoint2->SetPoint2(draggingHandle2 ? v2 : endpoint);
308 /*virtual*/ void Line::PointerReleased(void)
310 if (draggingHandle1 || draggingHandle2)
312 // Set the length (in case the global state was set to fixed (or not))
313 if (Object::fixedLength)
315 if (draggingHandle1) // startpoint
317 Vector v = Vector(position - endpoint).Unit() * length;
318 position = endpoint + v;
322 // Vector v1 = endpoint - position;
323 Vector v = Vector(endpoint - position).Unit() * length;
324 endpoint = position + v;
329 // Otherwise, we calculate the new length, just in case on the next move
330 // it turns out to have a fixed length. :-)
331 length = Vector(endpoint - position).Magnitude();
334 if (!Object::fixedAngle)
336 // Calculate the new angle, just in case on the next move it turns out to
338 angle = Vector(endpoint - position).Unit();
342 draggingLine = false;
343 draggingHandle1 = false;
344 draggingHandle2 = false;
346 // hitPoint1 = hitPoint2 = hitLine = false;
348 // Here we check for just a click: If object was clicked and dragged, then
349 // revert to the old state (OSInactive). Otherwise, keep the new state that
351 /*Maybe it would be better to just check for "object was dragged" state and not have to worry
352 about keeping track of old states...
354 if (objectWasDragged)
359 void Line::SetDimensionOnPoint1(Dimension * dimension)
361 dimPoint1 = dimension;
364 dimension->SetPoint1(position);
367 void Line::SetDimensionOnPoint2(Dimension * dimension)
369 dimPoint2 = dimension;
372 dimension->SetPoint2(endpoint);
375 void Line::SetDimensionOnLine(Dimension * dimension/*=NULL*/)
377 // If they don't pass one in, create it for the caller.
378 if (dimension == NULL)
380 dimension = new Dimension(&position, &endpoint, this);
383 parent->Add(dimension);
386 attachedDimension = dimension;
388 // After we set the points here, we don't have to care about them anymore.
391 dimension->SetPoint1(&position);
392 dimension->SetPoint2(&endpoint);
397 bool Line::HitTest(Point point)
401 hitPoint1 = hitPoint2 = hitLine = false;
402 Vector lineSegment = endpoint - position;
403 Vector v1 = point - position;
404 Vector v2 = point - endpoint;
405 double parameterizedPoint = lineSegment.Dot(v1) / lineSegment.Magnitude(), distance;
407 // Geometric interpretation:
408 // The parameterized point on the vector lineSegment is where the perpendicular
409 // intersects lineSegment. If pp < 0, then the perpendicular lies beyond the 1st
410 // endpoint. If pp > length of ls, then the perpendicular lies beyond the 2nd endpoint.
412 if (parameterizedPoint < 0.0)
413 distance = v1.Magnitude();
414 else if (parameterizedPoint > lineSegment.Magnitude())
415 distance = v2.Magnitude();
417 // distance = ?Det?(ls, v1) / |ls|
418 distance = fabs((lineSegment.x * v1.y - v1.x * lineSegment.y) / lineSegment.Magnitude());
420 // Geometric interpretation of the above:
421 // If the segment endpoints are s and e, and the point is p, then the test
422 // for the perpendicular intercepting the segment is equivalent to insisting
423 // that the two dot products {s-e}.{s-p} and {e-s}.{e-p} are both non-negative.
424 // Perpendicular distance from the point to the segment is computed by first
425 // computing the area of the triangle the three points form, then dividing by
426 // the length of the segment. Distances are done just by the Pythagorean
427 // theorem. Twice the area of the triangle formed by three points is the
428 // determinant of the following matrix:
430 // sx sy 1 0 0 1 0 0 0
431 // ex ey 1 ==> ex ey 1 ==> ex ey 0
432 // px py 1 px py 1 px py 0
434 // By translating the start point to the origin, and subtracting row 1 from
435 // all other rows, we end up with the matrix on the right which greatly
436 // simplifies the calculation of the determinant.
438 //How do we determine distance here? Especially if zoomed in or out???
439 #warning "!!! Distances tested for may not be valid if zoomed in or out !!!"
440 if (v1.Magnitude() < 8.0)
442 else if (v2.Magnitude() < 8.0)
444 else if (distance < 5.0)
447 return StateChanged();
450 void Line::SaveState(void)
452 oldHitPoint1 = hitPoint1;
453 oldHitPoint2 = hitPoint2;
454 oldHitLine = hitLine;
457 bool Line::StateChanged(void)
459 if ((hitPoint1 != oldHitPoint1) || (hitPoint2 != oldHitPoint2) || (hitLine != oldHitLine))
466 Intersection of two lines:
468 Find where the lines with equations r = i + j + t (3i - j) and r = -i + s (j) intersect.
470 When they intersect, we can set the equations equal to one another:
472 i + j + t (3i - j) = -i + s (j)
474 Equating coefficients:
475 1 + 3t = -1 and 1 - t = s
476 So t = -2/3 and s = 5/3
478 The position vector of the intersection point is therefore given by putting t = -2/3 or s = 5/3 into one of the above equations. This gives -i +5j/3 .
481 so, let's say we have two lines, l1 and l2. Points are v0(p0x, p0y), v1(p1x, p1y) for l1
482 and v2(p2x, p2y), v3(p3x, p3y) for l2.
484 d1 = v1 - v0, d2 = v3 - v2
486 Our parametric equations for the line then are:
491 Set r1 = r2, thus we have:
493 v0 + t(d1) = v2 + s(d2)
495 Taking coefficients, we have:
497 p0x + t(d1x) = p2x + s(d2x)
498 p0y + t(d1y) = p2y + s(d2y)
502 t(d1x) - s(d2x) = p2x - p0x
503 t(d1y) - s(d2y) = p2y - p0y
505 Determinant D is ad - bc where the matrix look like:
510 so D = (d1x)(d2y) - (d2x)(d1y)
511 if D = 0, the lines are parallel.
512 Dx = (p2x - p0x)(d2y) - (d2x)(p2y - p0y)
513 Dy = (d1x)(p2y - p0y) - (p2x - p0x)(d1y)
516 We only need to calculate t, as we can then multiply it by d1 to get the intersection point.
518 ---------------------------------------------------------------------------------------------------
520 The first and most preferred method for intersection calculation is the perp-product calculation. There are two vectors, v1 and v2. Create a third vector vector between the starting points of these vectors, and calculate the perp product of v2 and the two other vectors. These two scalars have to be divided to get the mulitplication ratio of v1 to reach intersection point. So:
526 Perp product is equal with dot product of normal of first vector and the second vector, so we need normals:
533 dp1 = n3 . v2 = -by3 * bx2 + bx3 * by2;
534 dp2 = n1 . v2 = -by1 * bx2 + bx1 * by2;
537 crossing vector = v1 * ratio;
541 -----------------------------------
543 So... to code this, let's say we have two Lines: l1 & l2.
545 Vector v1 = l1.endpoint - l1.position;
546 Vector v2 = l2.endpoint - l2.position;
549 Vector normal1(-v1.y, v1.x);
550 Vector normal3(-v3.y, v3.x);
552 double dotProduct1 = v2.Dot(normal1);
553 double dotProduct2 = v2.Dot(normal3);
555 if (dotProduct2 == 0)
556 return ParallelLines;
559 // I think we'd still have to add the intersection to the position point to get the intersection...
560 Point intersection = v1 * (dotProduct1 / dotProduct2);