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Add a constraint to make line length equal arc length. That's quite 

tricky; can't just use the dot product, since that blows up when
you cross pi radians. A gear shift approach, use either sin or cos,
same kind of thing as the 3d-parallel constraint.

And report a NaN constraint as unconverged, of course.

[git-p4: depot-paths = "//depot/solvespace/": change = 1890]
solver
Jonathan Westhues 2009-01-08 09:22:59 -08:00
parent f9eedb4db7
commit 984956cbc7
8 changed files with 117 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
constraint.cpp
View File

@ -36,6 +36,7 @@ char *Constraint::DescriptionString(void) {
case PERPENDICULAR: s = "perpendicular"; break;
case EQUAL_RADIUS: s = "eq-radius"; break;
case EQUAL_ANGLE: s = "eq-angle"; break;
case EQUAL_LINE_ARC_LEN:s = "eq-line-len-arc-len"; break;
case COMMENT: s = "comment"; break;
default: s = "???"; break;
}
@ -239,6 +240,15 @@ void Constraint::MenuConstrain(int id) {
c.type = EQUAL_RADIUS;
c.entityA = gs.entity[0];
c.entityB = gs.entity[1];
} else if(gs.arcs == 1 && gs.lineSegments == 1 && gs.n == 2) {
c.type = EQUAL_LINE_ARC_LEN;
if(SS.GetEntity(gs.entity[0])->type == Entity::ARC_OF_CIRCLE) {
c.entityA = gs.entity[1];
c.entityB = gs.entity[0];
} else {
c.entityA = gs.entity[0];
c.entityB = gs.entity[1];
}
} else {
Error("Bad selection for equal length / radius constraint. "
"This constraint can apply to:\r\n\r\n"
@ -253,7 +263,9 @@ void Constraint::MenuConstrain(int id) {
"(equal angle between A,B and C,D)\r\n"
" * three line segments or normals "
"(equal angle between A,B and B,C)\r\n"
" * two circles or arcs (equal radius)\r\n");
" * two circles or arcs (equal radius)\r\n"
" * a line segment and an arc "
"(line segment length equals arc length)\r\n");
return;
}
if(c.type == EQUAL_ANGLE) {

43
constrainteq.cpp
View File

@ -249,6 +249,49 @@ void Constraint::GenerateReal(IdList<Equation,hEquation> *l) {
break;
}
case EQUAL_LINE_ARC_LEN: {
Entity *line = SS.GetEntity(entityA),
*arc = SS.GetEntity(entityB);
// Get the line length
ExprVector l0 = SS.GetEntity(line->point[0])->PointGetExprs(),
l1 = SS.GetEntity(line->point[1])->PointGetExprs();
Expr *ll = (l1.Minus(l0)).Magnitude();
// And get the arc radius, and the cosine of its angle
Entity *ao = SS.GetEntity(arc->point[0]),
*as = SS.GetEntity(arc->point[1]),
*af = SS.GetEntity(arc->point[2]);
ExprVector aos = (as->PointGetExprs()).Minus(ao->PointGetExprs()),
aof = (af->PointGetExprs()).Minus(ao->PointGetExprs());
Expr *r = aof.Magnitude();
ExprVector n = arc->Normal()->NormalExprsN();
ExprVector u = aos.WithMagnitude(Expr::From(1.0));
ExprVector v = n.Cross(u);
// so in our new csys, we start at (1, 0, 0)
Expr *costheta = aof.Dot(u)->Div(r);
Expr *sintheta = aof.Dot(v)->Div(r);
double thetas, thetaf, dtheta;
arc->ArcGetAngles(&thetas, &thetaf, &dtheta);
Expr *theta;
if(dtheta < 3*PI/4) {
theta = costheta->ACos();
} else if(dtheta < 5*PI/4) {
// As the angle crosses pi, cos theta is not invertible;
// so use the sine to stop blowing up
theta = Expr::From(PI)->Minus(sintheta->ASin());
} else {
theta = (Expr::From(2*PI))->Minus(costheta->ACos());
}
// And write the equation; r*theta = L
AddEq(l, (r->Times(theta))->Minus(ll), 0);
break;
}
case POINTS_COINCIDENT: {
Entity *a = SS.GetEntity(ptA);
Entity *b = SS.GetEntity(ptB);

56
drawconstraint.cpp
View File

@ -104,6 +104,30 @@ void Constraint::DoEqualLenTicks(Vector a, Vector b, Vector gn) {
LineDrawOrGetDistance(m.Minus(n), m.Plus(n));
}
void Constraint::DoEqualRadiusTicks(hEntity he) {
Entity *circ = SS.GetEntity(he);
Vector center = SS.GetEntity(circ->point[0])->PointGetNum();
double r = circ->CircleGetRadiusNum();
Quaternion q = circ->Normal()->NormalGetNum();
Vector u = q.RotationU(), v = q.RotationV();
double theta;
if(circ->type == Entity::CIRCLE) {
theta = PI/2;
} else if(circ->type == Entity::ARC_OF_CIRCLE) {
double thetaa, thetab, dtheta;
circ->ArcGetAngles(&thetaa, &thetab, &dtheta);
theta = thetaa + dtheta/2;
} else oops();
Vector d = u.ScaledBy(cos(theta)).Plus(v.ScaledBy(sin(theta)));
d = d.ScaledBy(r);
Vector p = center.Plus(d);
Vector tick = d.WithMagnitude(10/SS.GW.scale);
LineDrawOrGetDistance(p.Plus(tick), p.Minus(tick));
}
void Constraint::DoArcForAngle(Vector a0, Vector da, Vector b0, Vector db,
Vector offset, Vector *ref)
{
@ -505,30 +529,22 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
case EQUAL_RADIUS: {
for(int i = 0; i < 2; i++) {
Entity *circ = SS.GetEntity(i == 0 ? entityA : entityB);
Vector center = SS.GetEntity(circ->point[0])->PointGetNum();
double r = circ->CircleGetRadiusNum();
Quaternion q = circ->Normal()->NormalGetNum();
Vector u = q.RotationU(), v = q.RotationV();
double theta;
if(circ->type == Entity::CIRCLE) {
theta = PI/2;
} else if(circ->type == Entity::ARC_OF_CIRCLE) {
double thetaa, thetab, dtheta;
circ->ArcGetAngles(&thetaa, &thetab, &dtheta);
theta = thetaa + dtheta/2;
} else oops();
Vector d = u.ScaledBy(cos(theta)).Plus(v.ScaledBy(sin(theta)));
d = d.ScaledBy(r);
Vector p = center.Plus(d);
Vector tick = d.WithMagnitude(10/SS.GW.scale);
LineDrawOrGetDistance(p.Plus(tick), p.Minus(tick));
DoEqualRadiusTicks(i == 0 ? entityA : entityB);
}
break;
}
case EQUAL_LINE_ARC_LEN: {
Entity *line = SS.GetEntity(entityA);
DoEqualLenTicks(
SS.GetEntity(line->point[0])->PointGetNum(),
SS.GetEntity(line->point[1])->PointGetNum(),
gn);
DoEqualRadiusTicks(entityB);
break;
}
case LENGTH_RATIO:
case EQUAL_LENGTH_LINES: {
Vector a, b;

15
expr.cpp
View File

@ -243,6 +243,8 @@ int Expr::Children(void) {
case SQUARE:
case SIN:
case COS:
case ASIN:
case ACOS:
return 1;
default: oops();
@ -312,6 +314,8 @@ double Expr::Eval(void) {
case SQUARE: { double r = a->Eval(); return r*r; }
case SIN: return sin(a->Eval());
case COS: return cos(a->Eval());
case ACOS: return acos(a->Eval());
case ASIN: return asin(a->Eval());
default: oops();
}
@ -349,6 +353,13 @@ Expr *Expr::PartialWrt(hParam p) {
case SIN: return (a->Cos())->Times(a->PartialWrt(p));
case COS: return ((a->Sin())->Times(a->PartialWrt(p)))->Negate();
case ASIN:
return (From(1)->Div((From(1)->Minus(a->Square()))->Sqrt()))
->Times(a->PartialWrt(p));
case ACOS:
return (From(-1)->Div((From(1)->Minus(a->Square()))->Sqrt()))
->Times(a->PartialWrt(p));
default: oops();
}
}
@ -421,6 +432,8 @@ Expr *Expr::FoldConstants(void) {
case NEGATE:
case SIN:
case COS:
case ASIN:
case ACOS:
if(n->a->op == CONSTANT) {
double nv = n->Eval();
n->op = CONSTANT;
@ -526,6 +539,8 @@ p:
case SQUARE: App("(square "); a->PrintW(); App(")"); break;
case SIN: App("(sin "); a->PrintW(); App(")"); break;
case COS: App("(cos "); a->PrintW(); App(")"); break;
case ASIN: App("(asin "); a->PrintW(); App(")"); break;
case ACOS: App("(acos "); a->PrintW(); App(")"); break;
default: oops();
}

4
expr.h
View File

@ -29,6 +29,8 @@ public:
static const int SQUARE = 106;
static const int SIN = 107;
static const int COS = 108;
static const int ASIN = 109;
static const int ACOS = 110;
// Special helpers for when we're parsing an expression from text.
// Initially, literals (like a constant number) appear in the same
@ -70,6 +72,8 @@ public:
inline Expr *Square(void) { return AnyOp(SQUARE, NULL); }
inline Expr *Sin (void) { return AnyOp(SIN, NULL); }
inline Expr *Cos (void) { return AnyOp(COS, NULL); }
inline Expr *ASin (void) { return AnyOp(ASIN, NULL); }
inline Expr *ACos (void) { return AnyOp(ACOS, NULL); }
Expr *PartialWrt(hParam p);
double Eval(void);

2
sketch.h
View File

@ -458,6 +458,7 @@ public:
static const int EQ_LEN_PT_LINE_D = 52;
static const int EQ_PT_LN_DISTANCES = 53;
static const int EQUAL_ANGLE = 54;
static const int EQUAL_LINE_ARC_LEN = 55;
static const int SYMMETRIC = 60;
static const int SYMMETRIC_HORIZ = 61;
static const int SYMMETRIC_VERT = 62;
@ -527,6 +528,7 @@ public:
void DoLabel(Vector ref, Vector *labelPos, Vector gr, Vector gu);
void DoProjectedPoint(Vector *p);
void DoEqualLenTicks(Vector a, Vector b, Vector gn);
void DoEqualRadiusTicks(hEntity he);
double GetDistance(Point2d mp);
Vector GetLabelPos(void);

2
system.cpp
View File

@ -516,7 +516,7 @@ didnt_converge:
(g->solved.remove).Clear();
SS.constraint.ClearTags();
for(i = 0; i < eq.n; i++) {
if(fabs(mat.B.num[i]) > CONVERGE_TOLERANCE) {
if(fabs(mat.B.num[i]) > CONVERGE_TOLERANCE || isnan(mat.B.num[i])) {
// This constraint is unsatisfied.
if(!mat.eq[i].isFromConstraint()) continue;

3
textwin.cpp
View File

@ -343,6 +343,9 @@ void TextWindow::DescribeSelection(void) {
double r = e->CircleGetRadiusNum();
Printf(true, " diameter = %Fi%s", SS.MmToString(r*2));
Printf(false, " radius = %Fi%s", SS.MmToString(r));
double thetas, thetaf, dtheta;
e->ArcGetAngles(&thetas, &thetaf, &dtheta);
Printf(false, " arc len = %Fi%s", SS.MmToString(dtheta*r));
break;
}
case Entity::CIRCLE: {