72 lines
2.2 KiB
C++
72 lines
2.2 KiB
C++
/*
|
|
* \brief Utilities for calculating bezier curves
|
|
* \date 2017-07-28
|
|
* \author Norman Feske
|
|
*/
|
|
|
|
/*
|
|
* Copyright (C) 2017 Genode Labs GmbH
|
|
*
|
|
* This file is part of the Genode OS framework, which is distributed
|
|
* under the terms of the GNU Affero General Public License version 3.
|
|
*/
|
|
|
|
#ifndef _INCLUDE__GEMS__BEZIER_H_
|
|
#define _INCLUDE__GEMS__BEZIER_H_
|
|
|
|
/**
|
|
* Calculate quadratic bezier curve
|
|
*
|
|
* \param draw_line functor to be called to draw a line segment
|
|
* \param levels number of sub divisions
|
|
*
|
|
* The coordinates are specified in clock-wise order with point 1 being
|
|
* the start and point 3 the end of the curve.
|
|
*/
|
|
template <typename FUNC>
|
|
static inline void bezier(long x1, long y1, long x2, long y2, long x3, long y3,
|
|
FUNC const &draw_line, unsigned levels)
|
|
{
|
|
if (levels-- == 0) {
|
|
draw_line(x1, y1, x3, y3);
|
|
return;
|
|
}
|
|
|
|
long const x12 = (x1 + x2) / 2, y12 = (y1 + y2) / 2,
|
|
x23 = (x2 + x3) / 2, y23 = (y2 + y3) / 2,
|
|
x123 = (x12 + x23) / 2, y123 = (y12 + y23) / 2;
|
|
|
|
bezier(x1, y1, x12, y12, x123, y123, draw_line, levels);
|
|
bezier(x123, y123, x23, y23, x3, y3, draw_line, levels);
|
|
}
|
|
|
|
|
|
/**
|
|
* Calculate cubic bezier curve
|
|
*
|
|
* The arguments correspond to those of the quadratic version but with point 4
|
|
* being the end of the curve.
|
|
*/
|
|
template <typename FUNC>
|
|
static inline void bezier(long x1, long y1, long x2, long y2,
|
|
long x3, long y3, long x4, long y4,
|
|
FUNC const &draw_line, unsigned levels)
|
|
{
|
|
if (levels-- == 0) {
|
|
draw_line(x1, y1, x4, y4);
|
|
return;
|
|
}
|
|
|
|
long const x12 = (x1 + x2) / 2, y12 = (y1 + y2) / 2,
|
|
x23 = (x2 + x3) / 2, y23 = (y2 + y3) / 2,
|
|
x34 = (x3 + x4) / 2, y34 = (y3 + y4) / 2,
|
|
x123 = (x12 + x23) / 2, y123 = (y12 + y23) / 2,
|
|
x234 = (x23 + x34) / 2, y234 = (y23 + y34) / 2,
|
|
x1234 = (x123 + x234) / 2, y1234 = (y123 + y234) / 2;
|
|
|
|
bezier(x1, y1, x12, y12, x123, y123, x1234, y1234, draw_line, levels);
|
|
bezier(x1234, y1234, x234, y234, x34, y34, x4, y4, draw_line, levels);
|
|
}
|
|
|
|
#endif /* _INCLUDE__GEMS__BEZIER_H_ */
|