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"
24 Line::Line(Vector p1, Vector p2, Object * p/*= NULL*/): Object(p1, p), endpoint(p2),
25 draggingLine(false), draggingHandle1(false), draggingHandle2(false), //needUpdate(false),
26 length(Vector::Magnitude(p2, p1)), hitPoint1(false), hitPoint2(false), hitLine(false)
32 // If there are any attached Dimensions, we must set the attachment points
33 // to NULL since they will no longer be valid.
34 if (attachedDimension)
36 attachedDimension->SetPoint1(NULL);
37 attachedDimension->SetPoint2(NULL);
39 // IT WOULD BE NICE to have any object points attached to this line automagically
40 // connect to this dimension object at this point, instead of just becoming
44 /*virtual*/ void Line::Draw(QPainter * painter)
46 painter->setPen(QPen(Qt::red, 2.0, Qt::DotLine));
48 if ((state == OSSelected) || ((state == OSInactive) && hitPoint1))
49 painter->drawEllipse(QPointF(position.x, position.y), 4.0, 4.0);
51 if ((state == OSSelected) || ((state == OSInactive) && hitPoint2))
52 painter->drawEllipse(QPointF(endpoint.x, endpoint.y), 4.0, 4.0);
54 if ((state == OSInactive) && !hitLine)
55 painter->setPen(QPen(Qt::black, 1.0, Qt::SolidLine));
57 if (Object::fixedLength && (draggingHandle1 || draggingHandle2))
59 Vector point1 = (draggingHandle1 ? endpoint : position);
60 Vector point2 = (draggingHandle1 ? position : endpoint);
62 Vector current(point2 - point1);
63 Vector v = current.Unit() * length;
64 Vector v2 = point1 + v;
65 painter->drawLine((int)point1.x, (int)point1.y, (int)v2.x, (int)v2.y);
67 if (current.Magnitude() > length)
69 painter->setPen(QPen(QColor(128, 0, 0), 1.0, Qt::DashLine));
70 painter->drawLine((int)v2.x, (int)v2.y, (int)point2.x, (int)point2.y);
74 painter->drawLine((int)position.x, (int)position.y, (int)endpoint.x, (int)endpoint.y);
77 /*virtual*/ Vector Line::Center(void)
79 // Technically, this is the midpoint but who are we to quibble? :-)
80 Vector v((position.x - endpoint.x) / 2.0, (position.y - endpoint.y) / 2.0);
84 /*virtual*/ bool Line::Collided(Vector point)
87 // Actually, we can, since this is a mouse down event here.
88 objectWasDragged = false;
92 There's a small problem here with the implementation: You can have a dimension tied
93 to only one point while at the same time you can have a dimension sitting on this line.
94 Since there's only *one* dimPoint for each point, this can be problematic...
96 We solve this by allowing only *one* Dimension object to be attached to the Line,
97 Arc, etc. and by giving the Dimension object a pointer to our endpoints.
99 Problem still arises when we delete this object; The attached Dimension object will
100 then have bad pointers! What is *should* do is delete the object if and only if this
101 line is not attached to any other object. If it is, then one of those attachment
102 points should be sent to the dimension object (done for position & endpoint).
104 NOTE: The STL vector<T> *does not* take ownership of pointers, therefore is suitable
107 Also: It would be nice to have a preview of the dimension being drawn, with a modifier
108 key to make it draw/show on the other side...
110 TODO: Make Dimension preview with modifier keys for showing on other side
112 // Is the dimension tool active? Let's use it:
115 // User clicked on the line itself (endpoint checks should preceed this one):
116 // (Priorities are taken care of in HitTest()...)
119 if (attachedDimension == NULL)
121 // How to get this object into the top level container???
123 The real question is do we care. I think so, because if this isn't in the top
124 level container, it won't get drawn...
125 But we can fix that by making this object call any attached object's (like
126 a dimension only) Draw() function... :-/
128 attachedDimension = new Dimension(&position, &endpoint, this);
131 parent->Add(attachedDimension);
135 // If there's one already there, tell it to flip sides...
136 attachedDimension->FlipSides();
144 if (state == OSInactive)
146 //printf("Line: pp = %lf, length = %lf, distance = %lf\n", parameterizedPoint, lineSegment.Magnitude(), distance);
147 //printf(" v1.Magnitude = %lf, v2.Magnitude = %lf\n", v1.Magnitude(), v2.Magnitude());
148 //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);
150 //How to translate this into pixels from Document space???
151 //Maybe we need to pass a scaling factor in here from the caller? That would make sense, as
152 //the caller knows about the zoom factor and all that good kinda crap
153 //I think what's needed is an Object class variable/method that can be changed by the TLC and
154 //called in derived classes to properly scale the location to the current zoom level. That *should* work.
156 // ALSO: Need to code a global (read: Object class) variable that tells use whether a modifier
157 // key was pressed in addition to the mouse click, so we can do stuff like, say, hold
158 // down CTRL and be able to do multiple selecting of objects (in that case, we would
159 // keep the Object state from changing).
164 oldPoint = position; //maybe "position"?
165 draggingHandle1 = true;
172 oldPoint = endpoint; //maybe "position"?
173 draggingHandle2 = true;
185 else if (state == OSSelected)
187 // Here we test for collision with handles as well! (SOON!) [I think it works...NOPE]
190 if (v1.Magnitude() < 2.0) // Handle #1
191 else if (v2.Magnitude() < 2.0) // Handle #2
196 // state = OSInactive;
203 // If we got here, we clicked on nothing, so set the object to inactive.
204 // (Once we can read key modifiers, we can override this to allow multiple selection.)
209 /*virtual*/ void Line::PointerMoved(Vector point)
211 // Hit test tells us what we hit (if anything) through boolean variables. It
212 // also tells us whether or not the state changed.
213 needUpdate = HitTest(point);
215 objectWasDragged = (draggingLine | draggingHandle1 | draggingHandle2);
217 if (objectWasDragged)
219 Vector delta = point - oldPoint;
221 if (draggingHandle1 || draggingLine)
224 if (draggingHandle2 || draggingLine)
232 We can't count on any coupling between the dimension object and us, so how do we do this???
233 Also, there may be more than one Dimension object connected to a single endpoint!
236 - Keep track of the state of the connected dimension
237 - Pass the Dimension the point that's being changed and the delta
240 - Pass the point in a notification function (how?)
241 - Pass the point as a reference to the class instance object (&endpoint). This way, the line
242 doesn't have to care about keeping track of Dimensions connected to it. But still have to
243 care about other connected entities (other Lines, Circles, Arcs, Splines, Texts, etc). I
244 think I'd be OK with this.
245 Since the Dimension has a pointer to our object, all we have to do is update our coordinates
246 and the Dimension object will adjust itself on the next repaint. Problem solved, and we don't
247 have to know anything about how many Dimensions are connected to us, or where! \o/
248 The question then becomes, how do we do this kind of coupling???
250 We need to know about connected entities so that we can have them either move in expected ways
251 or constrain the movement of this Line object. This is how we will be a cut above all other CAD
252 software currently out there: the GUI will try to do the right thing, most of the time. :-)
256 // should only do this if "Fixed Length" is set... !!! FIX !!! [DONE]
257 Vector point1 = (draggingHandle1 ? endpoint : position);
258 Vector point2 = (draggingHandle1 ? position : endpoint);
260 Vector current(point2, point1);
261 Vector v = current.Unit() * length;
262 Vector v2 = point1 + v;
265 if (!Object::fixedLength)
268 //If we tell the dimension to flip sides, this is no longer a valid
269 //assumption. !!! FIX !!!
270 //Ideally, we should just send the point that's changing to the Dimension object
271 //and have it figure out which point needs to move... Or is it???
272 // Ideally, we shouldn't have to fuck around with this shit. We need to fix the rendering code
273 // so that we don't have to wait until the dragging is done to correct the position of the
274 // point in question, but we'd need another variable tho.
277 dimPoint1->SetPoint1(draggingHandle1 ? v2 : position);
280 dimPoint2->SetPoint2(draggingHandle2 ? v2 : endpoint);
285 /*virtual*/ void Line::PointerReleased(void)
287 if (draggingHandle1 || draggingHandle2)
289 // Set the length (in case the global state was set to fixed (or not))
290 if (Object::fixedLength)
292 if (draggingHandle1) // startpoint
294 Vector v = Vector(position - endpoint).Unit() * length;
295 position = endpoint + v;
299 // Vector v1 = endpoint - position;
300 Vector v = Vector(endpoint - position).Unit() * length;
301 endpoint = position + v;
306 // Otherwise, we calculate the new length, just in case on the next move
307 // it turns out to have a fixed length. :-)
308 length = Vector(endpoint - position).Magnitude();
312 draggingLine = false;
313 draggingHandle1 = false;
314 draggingHandle2 = false;
316 // hitPoint1 = hitPoint2 = hitLine = false;
318 // Here we check for just a click: If object was clicked and dragged, then
319 // revert to the old state (OSInactive). Otherwise, keep the new state that
321 /*Maybe it would be better to just check for "object was dragged" state and not have to worry
322 about keeping track of old states...
324 if (objectWasDragged)
329 void Line::SetDimensionOnPoint1(Dimension * dimension)
331 dimPoint1 = dimension;
334 dimension->SetPoint1(position);
337 void Line::SetDimensionOnPoint2(Dimension * dimension)
339 dimPoint2 = dimension;
342 dimension->SetPoint2(endpoint);
345 void Line::SetDimensionOnLine(Dimension * dimension/*=NULL*/)
347 // If they don't pass one in, create it for the caller.
348 if (dimension == NULL)
350 dimension = new Dimension(&position, &endpoint, this);
353 parent->Add(dimension);
356 attachedDimension = dimension;
358 // After we set the points here, we don't have to care about them anymore.
361 dimension->SetPoint1(&position);
362 dimension->SetPoint2(&endpoint);
367 bool Line::HitTest(Point point)
371 hitPoint1 = hitPoint2 = hitLine = false;
372 Vector lineSegment = endpoint - position;
373 Vector v1 = point - position;
374 Vector v2 = point - endpoint;
375 double parameterizedPoint = lineSegment.Dot(v1) / lineSegment.Magnitude(), distance;
377 // Geometric interpretation:
378 // The parameterized point on the vector lineSegment is where the perpendicular
379 // intersects lineSegment. If pp < 0, then the perpendicular lies beyond the 1st
380 // endpoint. If pp > length of ls, then the perpendicular lies beyond the 2nd endpoint.
382 if (parameterizedPoint < 0.0)
383 distance = v1.Magnitude();
384 else if (parameterizedPoint > lineSegment.Magnitude())
385 distance = v2.Magnitude();
387 // distance = ?Det?(ls, v1) / |ls|
388 distance = fabs((lineSegment.x * v1.y - v1.x * lineSegment.y) / lineSegment.Magnitude());
390 // Geometric interpretation of the above:
391 // If the segment endpoints are s and e, and the point is p, then the test
392 // for the perpendicular intercepting the segment is equivalent to insisting
393 // that the two dot products {s-e}.{s-p} and {e-s}.{e-p} are both non-negative.
394 // Perpendicular distance from the point to the segment is computed by first
395 // computing the area of the triangle the three points form, then dividing by
396 // the length of the segment. Distances are done just by the Pythagorean
397 // theorem. Twice the area of the triangle formed by three points is the
398 // determinant of the following matrix:
400 // sx sy 1 0 0 1 0 0 0
401 // ex ey 1 ==> ex ey 1 ==> ex ey 0
402 // px py 1 px py 1 px py 0
404 // By translating the start point to the origin, and subtracting row 1 from
405 // all other rows, we end up with the matrix on the right which greatly
406 // simplifies the calculation of the determinant.
408 //How do we determine distance here? Especially if zoomed in or out???
409 #warning "!!! Distances tested for may not be valid if zoomed in or out !!!"
410 if (v1.Magnitude() < 8.0)
412 else if (v2.Magnitude() < 8.0)
414 else if (distance < 5.0)
417 return StateChanged();
420 void Line::SaveState(void)
422 oldHitPoint1 = hitPoint1;
423 oldHitPoint2 = hitPoint2;
424 oldHitLine = hitLine;
427 bool Line::StateChanged(void)
429 if ((hitPoint1 != oldHitPoint1) || (hitPoint2 != oldHitPoint2) || (hitLine != oldHitLine))
436 Intersection of two lines:
438 Find where the lines with equations r = i + j + t (3i - j) and r = -i + s (j) intersect.
440 When they intersect, we can set the equations equal to one another:
442 i + j + t (3i - j) = -i + s (j)
444 Equating coefficients:
445 1 + 3t = -1 and 1 - t = s
446 So t = -2/3 and s = 5/3
448 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 .
451 so, let's say we have two lines, l1 and l2. Points are v0(p0x, p0y), v1(p1x, p1y) for l1
452 and v2(p2x, p2y), v3(p3x, p3y) for l2.
454 d1 = v1 - v0, d2 = v3 - v2
456 Our parametric equations for the line then are:
461 Set r1 = r2, thus we have:
463 v0 + t(d1) = v2 + s(d2)
465 Taking coefficients, we have:
467 p0x + t(d1x) = p2x + s(d2x)
468 p0y + t(d1y) = p2y + s(d2y)
472 t(d1x) - s(d2x) = p2x - p0x
473 t(d1y) - s(d2y) = p2y - p0y
475 Determinant D is ad - bc where the matrix look like:
480 so D = (d1x)(d2y) - (d2x)(d1y)
481 if D = 0, the lines are parallel.
482 Dx = (p2x - p0x)(d2y) - (d2x)(p2y - p0y)
483 Dy = (d1x)(p2y - p0y) - (p2x - p0x)(d1y)
486 We only need to calculate t, as we can then multiply it by d1 to get the intersection point.
488 ---------------------------------------------------------------------------------------------------
490 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:
496 Perp product is equal with dot product of normal of first vector and the second vector, so we need normals:
503 dp1 = n3 . v2 = -by3 * bx2 + bx3 * by2;
504 dp2 = n1 . v2 = -by1 * bx2 + bx1 * by2;
507 crossing vector = v1 * ratio;
511 -----------------------------------
513 So... to code this, let's say we have two Lines: l1 & l2.
515 Vector v1 = l1.endpoint - l1.position;
516 Vector v2 = l2.endpoint - l2.position;
519 Vector normal1(-v1.y, v1.x);
520 Vector normal3(-v3.y, v3.x);
522 double dotProduct1 = v2.Dot(normal1);
523 double dotProduct2 = v2.Dot(normal3);
525 if (dotProduct2 == 0)
526 return ParallelLines;
529 // I think we'd still have to add the intersection to the position point to get the intersection...
530 Point intersection = v1 * (dotProduct1 / dotProduct2);