Files
MagicSetEditor2/src/gfx/bezier.cpp
T
coppro cf91f9c43b Update copryright date to 2010.
git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@1438 0fc631ac-6414-0410-93d0-97cfa31319b6
2010-03-01 23:33:25 +00:00

250 lines
9.5 KiB
C++

//+----------------------------------------------------------------------------+
//| Description: Magic Set Editor - Program to make Magic (tm) cards |
//| Copyright: (C) 2001 - 2010 Twan van Laarhoven and Sean Hunt |
//| License: GNU General Public License 2 or later (see file COPYING) |
//+----------------------------------------------------------------------------+
// ----------------------------------------------------------------------------- : Includes
#include <util/prec.hpp>
#include <util/rotation.hpp>
#include <gfx/bezier.hpp>
#include <gfx/polynomial.hpp>
// ----------------------------------------------------------------------------- : Evaluation
BezierCurve::BezierCurve(const Vector2D& p0, const Vector2D& p1, const Vector2D& p2, const Vector2D& p3) {
// calculate coefficients
c = (p1 - p0) * 3.0;
b = (p2 - p1) * 3.0 - c;
a = (p3 - p0) - c - b;
d = p0;
}
BezierCurve::BezierCurve(const ControlPoint& p0, const ControlPoint& p3) {
// calculate coefficients
c = p0.delta_after * 3.0;
b = (p3.pos + p3.delta_before - p0.pos - p0.delta_after) * 3.0 - c;
a = (p3.pos - p0.pos) - c - b;
d = p0.pos;
}
void deCasteljau(Vector2D a1, Vector2D a2, Vector2D a3, Vector2D a4,
Vector2D& b2, Vector2D& b3, Vector2D& b4c1,
Vector2D& c2, Vector2D& c3, double t)
{
b2 = a1 + (a2 - a1) * t;
Vector2D mid23 = a2 + (a3 - a2) * t;
c3 = a3 + (a4 - a3) * t;
b3 = b2 + (mid23 - b2) * t;
c2 = mid23 + (c3 - mid23) * t;
b4c1 = b3 + (c2 - b3) * t;
}
void deCasteljau(ControlPoint& a, ControlPoint& b, double t, ControlPoint& mid) {
deCasteljau(a.pos, a.delta_after, b.delta_before, b.pos, t, mid);
}
void deCasteljau(const Vector2D& a1, Vector2D& a21, Vector2D& a34, const Vector2D& a4, double t, ControlPoint& out) {
Vector2D half21 = a21 * t;
Vector2D half34 = a34 * (1-t);
Vector2D mid23 = (a1 + a21) * (1-t) + (a34 + a4) * t;
Vector2D mid23h21 = (a1 + half21) * (1-t) + mid23 * t;
Vector2D mid23h34 = (a4 + half34) * t + mid23 * (1-t);
out.pos = mid23h21 * (1-t) + mid23h34 * t;
out.delta_before = mid23h21 - out.pos;
out.delta_after = mid23h34 - out.pos;
a21 = half21;
a34 = half34;
}
// ----------------------------------------------------------------------------- : Drawing
void curve_subdivide(const BezierCurve& c, const Vector2D& p0, const Vector2D& p1, double t0, double t1, const Vector2D& origin, const Matrix2D& m, vector<wxPoint>& out, UInt level) {
if (level <= 0) return;
double midtime = (t0+t1) * 0.5f;
Vector2D midpoint = c.pointAt(midtime);
Vector2D d0 = p0 - midpoint;
Vector2D d1 = midpoint - p1;
// Determine treshold for subdivision, greater angle -> subdivide
// greater size -> subdivide
double treshold = fabs( atan2(d0.x,d0.y) - atan2(d1.x,d1.y)) * (p0-p1).lengthSqr();
bool subdivide = treshold >= .0001;
// subdivide left
curve_subdivide(c, p0, midpoint, t0, midtime, origin, m, out, level - 1);
// add midpoint
if (subdivide) {
out.push_back(origin + midpoint * m);
}
// subdivide right
curve_subdivide(c, midpoint, p1, midtime, t1, origin, m, out, level - 1);
}
void segment_subdivide(const ControlPoint& p0, const ControlPoint& p1, const Vector2D& origin, const Matrix2D& m, vector<wxPoint>& out) {
assert(p0.segment_after == p1.segment_before);
// always the start
out.push_back(origin + p0.pos * m);
if (p0.segment_after == SEGMENT_CURVE) {
// need more points?
BezierCurve curve(p0,p1);
curve_subdivide(curve, p0.pos, p1.pos, 0, 1, origin, m, out, 5);
}
}
// ----------------------------------------------------------------------------- : Bounds
Bounds segment_bounds(const Vector2D& origin, const Matrix2D& m, const ControlPoint& p1, const ControlPoint& p2) {
assert(p1.segment_after == p2.segment_before);
if (p1.segment_after == SEGMENT_LINE) {
return line_bounds (origin, m, p1.pos, p2.pos);
} else {
return bezier_bounds(origin, m, p1, p2);
}
}
Bounds bezier_bounds(const Vector2D& origin, const Matrix2D& m, const ControlPoint& p1, const ControlPoint& p2) {
assert(p1.segment_after == SEGMENT_CURVE);
// Transform the control points
Vector2D r1 = origin + p1.pos * m;
Vector2D r2 = origin + (p1.pos + p1.delta_after) * m;
Vector2D r3 = origin + (p2.pos + p2.delta_before) * m;
Vector2D r4 = origin + p2.pos * m;
// First of all, the corners should be in the bounding box
Bounds bounds(r1);
bounds.update(r4);
// Solve the derivative of the bezier curve to find its extremes
// It's only a quadtratic equation :)
BezierCurve curve(r1,r2,r3,r4);
double roots[4];
UInt count;
count = solve_quadratic(3*curve.a.x, 2*curve.b.x, curve.c.x, roots);
count += solve_quadratic(3*curve.a.y, 2*curve.b.y, curve.c.y, roots + count);
// now check them for min/max
for (UInt i = 0 ; i < count ; ++i) {
double t = roots[i];
if (t >=0 && t <= 1) {
bounds.update(curve.pointAt(t));
}
}
return bounds;
}
Bounds line_bounds(const Vector2D& origin, const Matrix2D& m, const Vector2D& p1, const Vector2D& p2) {
Bounds bounds(origin + p1 * m);
bounds.update(origin + p2 * m);
return bounds;
}
// ----------------------------------------------------------------------------- : Point tests
// Is a point inside a symbol shape?
bool point_in_shape(const Vector2D& pos, const SymbolShape& shape) {
// Step 1. compare bounding box of the part
if (!shape.bounds.contains(pos)) return false;
// Step 2. trace ray outward, count intersections
int count = 0;
size_t size = shape.points.size();
for(size_t i = 0 ; i < size ; ++i) {
ControlPointP p1 = shape.getPoint((int) i);
ControlPointP p2 = shape.getPoint((int) i + 1);
if (p1->segment_after == SEGMENT_LINE) {
count += intersect_line_ray (p1->pos, p2->pos, pos);
} else {
count += intersect_bezier_ray(*p1, *p2, pos);
}
}
return count & 1; // odd number of intersections
}
// ----------------------------------------------------------------------------- : Finding points
bool pos_on_segment(const Vector2D& pos, double range, const ControlPoint& p1, const ControlPoint& p2, Vector2D& pOut, double& tOut) {
if (p1.segment_after == SEGMENT_CURVE) {
return pos_on_bezier(pos, range, p1, p2, pOut, tOut);
} else {
return pos_on_line (pos, range, p1.pos, p2.pos, pOut, tOut);
}
}
bool pos_on_bezier(const Vector2D& pos, double range, const ControlPoint& p1, const ControlPoint& p2, Vector2D& pOut, double& tOut) {
assert(p1.segment_after == SEGMENT_CURVE);
// Find intersections with the horizontal and vertical lines through p0
// theoretically we would need to check in all directions, but this covers enough
BezierCurve curve(p1, p2);
double roots[6];
UInt count;
count = solve_cubic(curve.a.y, curve.b.y, curve.c.y, curve.d.y - pos.y, roots);
count += solve_cubic(curve.a.x, curve.b.x, curve.c.x, curve.d.x - pos.x, roots + count); // append intersections
// take the best intersection point
double bestDistSqr = std::numeric_limits<double>::max(); //infinity
for(UInt i = 0 ; i < count ; ++i) {
double t = roots[i];
if (t >= 0 && t < 1) {
Vector2D pnt = curve.pointAt(t);
double distSqr = (pnt - pos).lengthSqr();
if (distSqr < bestDistSqr) {
bestDistSqr = distSqr;
pOut = pnt;
tOut = t;
}
}
}
return bestDistSqr <= range * range;
}
bool pos_on_line(const Vector2D& pos, double range, const Vector2D& p1, const Vector2D& p2, Vector2D& pOut, double& t) {
Vector2D p21 = p2 - p1;
double p21len = p21.lengthSqr();
if (p21len < 0.00001) return false; // line is too short
t = dot(p21, pos - p1) / p21len; // 'time' on line p1->p2
if (t < 0 || t > 1) return false; // outside segment
pOut = p1 + p21 * t; // point on line
Vector2D dist = pOut - pos; // distance to line
return dist.lengthSqr() <= range * range; // in range?
}
// ----------------------------------------------------------------------------- : Intersection
UInt intersect_bezier_ray(const ControlPoint& p1, const ControlPoint& p2, const Vector2D& pos) {
// Looking only at the y coordinate
// we can use the cubic formula to find roots, points where the horizontal line
// through pos intersects the (extended) curve
BezierCurve curve(p1,p2);
double roots[3];
UInt count = solve_cubic(curve.a.y, curve.b.y, curve.c.y, curve.d.y - pos.y, roots);
// now check if the solutions are left of pos.x
UInt solsInRange = 0;
for(UInt i = 0 ; i < count ; ++i) {
double t = roots[i];
if (t >= 0 && t < 1 && curve.pointAt(t).x < pos.x) {
solsInRange += 1;
}
}
return solsInRange;
}
bool intersect_line_ray(const Vector2D& p1, const Vector2D& p2, const Vector2D& pos) {
// Vector2D intersection = p1 + t * (p2 - p1)
// intersection.y == pos.y
// == p1.y + t * (p2.y - p1.y)
// => t == (pos.y - p1.y) / (p2.y - p1.y)
// intersection.x == p1.x + t * (p2.x - p1.x)
// == p1.x + (pos.y - p1.y) * (p2.x - p1.x) / (p2.y - p1.y)
double dy = p2.y - p1.y;
if (fabs(dy) < 0.0000000001) {
// horizontal line
return (p1.x > pos.x || p2.x > pos.x) && // starts to the left of pos
fabs(p1.y - pos.y) < 0.0000000001; // same y as pos
} else {
double dx = p2.x - p1.x;
double t = (pos.y - p1.y) / dy;
if (t < 0.0 || t >= 1.0) return false;
double intersectX = p1.x + t * dx;
return intersectX <= pos.x; // intersection is left of pos
}
}