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)
90 // Actually, we can, since this is a mouse down event here.
91 objectWasDragged = false;
95 There's a small problem here with the implementation: You can have a dimension tied
96 to only one point while at the same time you can have a dimension sitting on this line.
97 Since there's only *one* dimPoint for each point, this can be problematic...
99 We solve this by allowing only *one* Dimension object to be attached to the Line,
100 Arc, etc. and by giving the Dimension object a pointer to our endpoints.
102 Problem still arises when we delete this object; The attached Dimension object will
103 then have bad pointers! What it *should* do is delete the object if and only if this
104 line is not attached to any other object. If it is, then one of those attachment
105 points should be sent to the dimension object (done for position & endpoint).
107 NOTE: The STL vector<T> *does not* take ownership of pointers, therefore is suitable
110 Also: It would be nice to have a preview of the dimension being drawn, with a modifier
111 key to make it draw/show on the other side...
113 TODO: Make Dimension preview with modifier keys for showing on other side
115 // Is the dimension tool active? Let's use it:
118 // User clicked on the line itself (endpoint checks should preceed this one):
119 // (Priorities are taken care of in HitTest()...)
122 if (attachedDimension == NULL)
124 // How to get this object into the top level container???
126 The real question is do we care. I think so, because if this isn't in the top
127 level container, it won't get drawn...
128 But we can fix that by making this object call any attached object's (like
129 a dimension only) Draw() function... :-/
131 attachedDimension = new Dimension(&position, &endpoint, this);
134 parent->Add(attachedDimension);
138 // If there's one already there, tell it to flip sides...
139 attachedDimension->FlipSides();
147 if (state == OSInactive)
149 //printf("Line: pp = %lf, length = %lf, distance = %lf\n", parameterizedPoint, lineSegment.Magnitude(), distance);
150 //printf(" v1.Magnitude = %lf, v2.Magnitude = %lf\n", v1.Magnitude(), v2.Magnitude());
151 //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);
153 //How to translate this into pixels from Document space???
154 //Maybe we need to pass a scaling factor in here from the caller? That would make sense, as
155 //the caller knows about the zoom factor and all that good kinda crap
156 //I think what's needed is an Object class variable/method that can be changed by the TLC and
157 //called in derived classes to properly scale the location to the current zoom level. That *should* work.
159 // ALSO: Need to code a global (read: Object class) variable that tells use whether a modifier
160 // key was pressed in addition to the mouse click, so we can do stuff like, say, hold
161 // down CTRL and be able to do multiple selecting of objects (in that case, we would
162 // keep the Object state from changing).
167 oldPoint = position; //maybe "position"?
168 draggingHandle1 = true;
175 oldPoint = endpoint; //maybe "position"?
176 draggingHandle2 = true;
188 else if (state == OSSelected)
190 // Here we test for collision with handles as well! (SOON!) [I think it works...NOPE]
193 if (v1.Magnitude() < 2.0) // Handle #1
194 else if (v2.Magnitude() < 2.0) // Handle #2
199 // state = OSInactive;
206 // If we got here, we clicked on nothing, so set the object to inactive.
207 // (Once we can read key modifiers, we can override this to allow multiple selection.)
212 /*virtual*/ void Line::PointerMoved(Vector point)
214 // Hit test tells us what we hit (if anything) through boolean variables. It
215 // also tells us whether or not the state changed.
216 needUpdate = HitTest(point);
218 objectWasDragged = (draggingLine | draggingHandle1 | draggingHandle2);
220 if (objectWasDragged)
222 Vector delta = point - oldPoint;
224 if (draggingHandle1 || draggingLine)
227 if (draggingHandle2 || draggingLine)
235 We can't count on any coupling between the dimension object and us, so how do we do this???
236 Also, there may be more than one Dimension object connected to a single endpoint!
239 - Keep track of the state of the connected dimension
240 - Pass the Dimension the point that's being changed and the delta
243 - Pass the point in a notification function (how?)
244 - Pass the point as a reference to the class instance object (&endpoint). This way, the line
245 doesn't have to care about keeping track of Dimensions connected to it. But still have to
246 care about other connected entities (other Lines, Circles, Arcs, Splines, Texts, etc). I
247 think I'd be OK with this.
248 Since the Dimension has a pointer to our object, all we have to do is update our coordinates
249 and the Dimension object will adjust itself on the next repaint. Problem solved, and we don't
250 have to know anything about how many Dimensions are connected to us, or where! \o/
251 The question then becomes, how do we do this kind of coupling???
253 We need to know about connected entities so that we can have them either move in expected ways
254 or constrain the movement of this Line object. This is how we will be a cut above all other CAD
255 software currently out there: the GUI will try to do the right thing, most of the time. :-)
259 // should only do this if "Fixed Length" is set... !!! FIX !!! [DONE]
260 Vector point1 = (draggingHandle1 ? endpoint : position);
261 Vector point2 = (draggingHandle1 ? position : endpoint);
264 Vector current(point2, point1);
265 Vector v = current.Unit() * length;
266 Vector v2 = point1 + v;
269 if (!Object::fixedLength)
273 if (Object::fixedAngle)
275 // Here we calculate the component of the current vector along the fixed angle.
276 // A_compB = (A . Bu) * Bu
277 double magnitudeAlongB = Vector::Dot(Vector(point2 - point1), angle);
279 Actually, this isn't quite right. What we want to do is look for the intersection along either
280 the horizontal line or vertical line that intersects from the current mouse position.
284 position = endpoint + (angle * magnitudeAlongB);
287 endpoint = position + (angle * magnitudeAlongB);
292 //If we tell the dimension to flip sides, this is no longer a valid
293 //assumption. !!! FIX !!!
294 //Ideally, we should just send the point that's changing to the Dimension object
295 //and have it figure out which point needs to move... Or is it???
296 // Ideally, we shouldn't have to fuck around with this shit. We need to fix the rendering code
297 // so that we don't have to wait until the dragging is done to correct the position of the
298 // point in question, but we'd need another variable tho.
301 dimPoint1->SetPoint1(draggingHandle1 ? v2 : position);
304 dimPoint2->SetPoint2(draggingHandle2 ? v2 : endpoint);
309 /*virtual*/ void Line::PointerReleased(void)
311 if (draggingHandle1 || draggingHandle2)
313 // Set the length (in case the global state was set to fixed (or not))
314 if (Object::fixedLength)
316 if (draggingHandle1) // startpoint
318 Vector v = Vector(position - endpoint).Unit() * length;
319 position = endpoint + v;
323 // Vector v1 = endpoint - position;
324 Vector v = Vector(endpoint - position).Unit() * length;
325 endpoint = position + v;
330 // Otherwise, we calculate the new length, just in case on the next move
331 // it turns out to have a fixed length. :-)
332 length = Vector(endpoint - position).Magnitude();
335 if (!Object::fixedAngle)
337 // Calculate the new angle, just in case on the next move it turns out to
339 angle = Vector(endpoint - position).Unit();
343 draggingLine = false;
344 draggingHandle1 = false;
345 draggingHandle2 = false;
347 // hitPoint1 = hitPoint2 = hitLine = false;
349 // Here we check for just a click: If object was clicked and dragged, then
350 // revert to the old state (OSInactive). Otherwise, keep the new state that
352 /*Maybe it would be better to just check for "object was dragged" state and not have to worry
353 about keeping track of old states...
355 if (objectWasDragged)
360 void Line::SetDimensionOnPoint1(Dimension * dimension)
362 dimPoint1 = dimension;
365 dimension->SetPoint1(position);
368 void Line::SetDimensionOnPoint2(Dimension * dimension)
370 dimPoint2 = dimension;
373 dimension->SetPoint2(endpoint);
376 void Line::SetDimensionOnLine(Dimension * dimension/*=NULL*/)
378 // If they don't pass one in, create it for the caller.
379 if (dimension == NULL)
381 dimension = new Dimension(&position, &endpoint, this);
384 parent->Add(dimension);
387 attachedDimension = dimension;
389 // After we set the points here, we don't have to care about them anymore.
392 dimension->SetPoint1(&position);
393 dimension->SetPoint2(&endpoint);
398 bool Line::HitTest(Point point)
402 hitPoint1 = hitPoint2 = hitLine = false;
403 Vector lineSegment = endpoint - position;
404 Vector v1 = point - position;
405 Vector v2 = point - endpoint;
406 double parameterizedPoint = lineSegment.Dot(v1) / lineSegment.Magnitude(), distance;
408 // Geometric interpretation:
409 // The parameterized point on the vector lineSegment is where the perpendicular
410 // intersects lineSegment. If pp < 0, then the perpendicular lies beyond the 1st
411 // endpoint. If pp > length of ls, then the perpendicular lies beyond the 2nd endpoint.
413 if (parameterizedPoint < 0.0)
414 distance = v1.Magnitude();
415 else if (parameterizedPoint > lineSegment.Magnitude())
416 distance = v2.Magnitude();
418 // distance = ?Det?(ls, v1) / |ls|
419 distance = fabs((lineSegment.x * v1.y - v1.x * lineSegment.y) / lineSegment.Magnitude());
421 // Geometric interpretation of the above:
422 // If the segment endpoints are s and e, and the point is p, then the test
423 // for the perpendicular intercepting the segment is equivalent to insisting
424 // that the two dot products {s-e}.{s-p} and {e-s}.{e-p} are both non-negative.
425 // Perpendicular distance from the point to the segment is computed by first
426 // computing the area of the triangle the three points form, then dividing by
427 // the length of the segment. Distances are done just by the Pythagorean
428 // theorem. Twice the area of the triangle formed by three points is the
429 // determinant of the following matrix:
431 // sx sy 1 0 0 1 0 0 0
432 // ex ey 1 ==> ex ey 1 ==> ex ey 0
433 // px py 1 px py 1 px py 0
435 // By translating the start point to the origin, and subtracting row 1 from
436 // all other rows, we end up with the matrix on the right which greatly
437 // simplifies the calculation of the determinant.
439 //How do we determine distance here? Especially if zoomed in or out???
440 #warning "!!! Distances tested for may not be valid if zoomed in or out !!!"
441 if (v1.Magnitude() < 8.0)
443 else if (v2.Magnitude() < 8.0)
445 else if (distance < 5.0)
448 return StateChanged();
451 void Line::SaveState(void)
453 oldHitPoint1 = hitPoint1;
454 oldHitPoint2 = hitPoint2;
455 oldHitLine = hitLine;
458 bool Line::StateChanged(void)
460 if ((hitPoint1 != oldHitPoint1) || (hitPoint2 != oldHitPoint2) || (hitLine != oldHitLine))
467 Intersection of two lines:
469 Find where the lines with equations r = i + j + t (3i - j) and r = -i + s (j) intersect.
471 When they intersect, we can set the equations equal to one another:
473 i + j + t (3i - j) = -i + s (j)
475 Equating coefficients:
476 1 + 3t = -1 and 1 - t = s
477 So t = -2/3 and s = 5/3
479 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 .
482 so, let's say we have two lines, l1 and l2. Points are v0(p0x, p0y), v1(p1x, p1y) for l1
483 and v2(p2x, p2y), v3(p3x, p3y) for l2.
485 d1 = v1 - v0, d2 = v3 - v2
487 Our parametric equations for the line then are:
492 Set r1 = r2, thus we have:
494 v0 + t(d1) = v2 + s(d2)
496 Taking coefficients, we have:
498 p0x + t(d1x) = p2x + s(d2x)
499 p0y + t(d1y) = p2y + s(d2y)
503 t(d1x) - s(d2x) = p2x - p0x
504 t(d1y) - s(d2y) = p2y - p0y
506 Determinant D is ad - bc where the matrix look like:
511 so D = (d1x)(d2y) - (d2x)(d1y)
512 if D = 0, the lines are parallel.
513 Dx = (p2x - p0x)(d2y) - (d2x)(p2y - p0y)
514 Dy = (d1x)(p2y - p0y) - (p2x - p0x)(d1y)
517 We only need to calculate t, as we can then multiply it by d1 to get the intersection point.
519 ---------------------------------------------------------------------------------------------------
521 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:
527 Perp product is equal with dot product of normal of first vector and the second vector, so we need normals:
534 dp1 = n3 . v2 = -by3 * bx2 + bx3 * by2;
535 dp2 = n1 . v2 = -by1 * bx2 + bx1 * by2;
538 crossing vector = v1 * ratio;
542 -----------------------------------
544 So... to code this, let's say we have two Lines: l1 & l2.
546 Vector v1 = l1.endpoint - l1.position;
547 Vector v2 = l2.endpoint - l2.position;
550 Vector normal1(-v1.y, v1.x);
551 Vector normal3(-v3.y, v3.x);
553 double dotProduct1 = v2.Dot(normal1);
554 double dotProduct2 = v2.Dot(normal3);
556 if (dotProduct2 == 0)
557 return ParallelLines;
560 // I think we'd still have to add the intersection to the position point to get the intersection...
561 Point intersection = v1 * (dotProduct1 / dotProduct2);