/* * Clutter. * * An OpenGL based 'interactive canvas' library. * * Authored By Tomas Frydrych * * Copyright (C) 2007 OpenedHand * Copyright (C) 2013 Erick Pérez Castellanos * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library. If not, see . */ #include #include #include #include "clutter-bezier.h" #include "clutter-debug.h" /**************************************************************************** * ClutterBezier -- representation of a cubic bezier curve * * (private; a building block for the public bspline object) * ****************************************************************************/ /* * Constants for sampling of the bezier. Float point. */ #define CBZ_T_SAMPLES 128.0 #define CBZ_T_STEP (1.0 / CBZ_T_SAMPLES) /* * This is a private type representing a single cubic bezier */ struct _ClutterBezier { /* bezier coefficients */ gfloat ax; gfloat bx; gfloat cx; gfloat dx; gfloat ay; gfloat by; gfloat cy; gfloat dy; /* length of the bezier */ gfloat length; }; static gfloat _clutter_bezier_t2x (const ClutterBezier *b, gfloat t) { return b->ax * (1 - t) * (1 - t) * (1 - t) + b->bx * (1 - t) * (1 - t) * t + b->cx * (1 - t) * t * t + b->dx * t * t * t; } static gfloat _clutter_bezier_t2y (const ClutterBezier *b, gfloat t) { return b->ay * (1 - t) * (1 - t) * (1 - t) + b->by * (1 - t) * (1 - t) * t + b->cy * (1 - t) * t * t + b->dy * t * t * t; } /* * _clutter_bezier_new: * * Allocate the bezier * * Return value: The new bezier object. */ ClutterBezier * _clutter_bezier_new (void) { return g_slice_new0 (ClutterBezier); } /* * _clutter_bezier_free: * @b: The bezier to free * * Free the object */ void _clutter_bezier_free (ClutterBezier *b) { if (G_LIKELY (b)) g_slice_free (ClutterBezier, b); } /* * _clutter_bezier_clone_and_move: * @b: A #ClutterBezier for cloning * @x: The x coordinates of the new end of the bezier * @y: The y coordinates of the new end of the bezier * * Clone the bezier and move th end-point, leaving both control * points in place. * * Return value: The new bezier object. */ ClutterBezier * _clutter_bezier_clone_and_move (const ClutterBezier *b, gfloat x, gfloat y) { ClutterBezier * b2 = _clutter_bezier_new (); memcpy (b2, b, sizeof (ClutterBezier)); b2->dx += x; b2->dy += y; return b2; } /* * _clutter_bezier_advance: * @b: A #ClutterBezier * @L: A relative length * @knot: The point whith the calculated position * * Advances along the bezier @b to relative length @L and returns the coordinances * in @knot */ void _clutter_bezier_advance (const ClutterBezier *b, gfloat L, ClutterPoint *knot) { gfloat t; t = L; knot->x = _clutter_bezier_t2x (b, t); knot->y = _clutter_bezier_t2y (b, t); CLUTTER_NOTE (MISC, "advancing to relative point {%d,%d} by moving a distance equals to: %f, with t: %f", knot->x, knot->y, L, t); } /* * _clutter_bezier_init: * @b: A #ClutterBezier * @x_0: x coordinates of the start point of the cubic bezier * @y_0: y coordinates of the start point of the cubic bezier * @x_1: x coordinates of the first control point * @y_1: y coordinates of the first control point * @x_2: x coordinates of the second control point * @y_2: y coordinates of the second control point * @x_3: x coordinates of the end point of the cubic bezier * @y_3: y coordinates of the end point of the cubic bezier * * Initialize the data of the bezier object @b. */ void _clutter_bezier_init (ClutterBezier *b, gfloat x_0, gfloat y_0, gfloat x_1, gfloat y_1, gfloat x_2, gfloat y_2, gfloat x_3, gfloat y_3) { gfloat t; gint i; gfloat xp; gfloat yp; CLUTTER_NOTE (MISC, "Initializing bezier at {{%f,%f},{%f,%f},{%f,%f},{%f,%f}}", x_0, y_0, x_1, y_1, x_2, y_2, x_3, y_3); b->ax = x_0; b->ay = y_0; b->bx = 3 * x_1; b->by = 3 * y_1; b->cx = 3 * x_2; b->cy = 3 * y_2; b->dx = x_3; b->dy = y_3; b->length = 0.0; CLUTTER_NOTE (MISC, "Coefficients {{%f,%f},{%f,%f},{%f,%f},{%f,%f}}", b->ax, b->ay, b->bx, b->by, b->cx, b->cy, b->dx, b->dy); xp = b->ax; yp = b->ay; for (t = CBZ_T_STEP, i = 1; i <= CBZ_T_SAMPLES; ++i, t += CBZ_T_STEP) { gfloat x = _clutter_bezier_t2x (b, t); gfloat y = _clutter_bezier_t2y (b, t); b->length += sqrtf ((y - yp)*(y - yp) + (x - xp)*(x - xp)); xp = x; yp = y; } CLUTTER_NOTE (MISC, "length %f", b->length); } /* * _clutter_bezier_adjust: * @b: A #ClutterBezier object * @knot: The new position of the control point @ @indx: The index of the control point you want to move. * * Moves a control point at index @indx to location represented by @knot */ void _clutter_bezier_adjust (ClutterBezier *b, ClutterPoint *knot, guint indx) { gfloat x[4], y[4]; g_assert (indx < 4); x[0] = b->ax; y[0] = b->ay; x[1] = b->bx; y[1] = b->by; x[2] = b->cx; y[2] = b->cy; x[3] = b->dx; y[3] = b->dy; x[indx] = knot->x; y[indx] = knot->y; _clutter_bezier_init (b, x[0], y[0], x[1], y[1], x[2], y[2], x[3], y[3]); } /* * _clutter_bezier_get_length: * @b: A #ClutterBezier * * Return value: Returns the length of the bezier */ gfloat _clutter_bezier_get_length (const ClutterBezier *b) { return b->length; }