mirror of
https://github.com/brl/mutter.git
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77ec8774a0
Revert all the work that happened on the master branch.
Sadly, this is the only way to merge the current development branch back
into master.
It is now abundantly clear that I merged the 1.99 branch far too soon,
and that Clutter 2.0 won't happen any time soon, if at all.
Since having the development happen on a separate branch throws a lot of
people into confusion, let's undo the clutter-1.99 → master merge, and
move back the development of Clutter to the master branch.
In order to do so, we need to do some surgery to the Git repository.
First, we do a massive revert in a single commit of all that happened
since the switch to 1.99 and the API version bump done with the
89a2862b05 commit. The history is too long
to be reverted commit by commit without being extremely messy.
425 lines
11 KiB
C
425 lines
11 KiB
C
/*
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* Clutter.
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*
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* An OpenGL based 'interactive canvas' library.
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*
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* Authored By Tomas Frydrych <tf@openedhand.com>
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*
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* Copyright (C) 2007 OpenedHand
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <glib.h>
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#include <string.h>
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#include "clutter-bezier.h"
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#include "clutter-debug.h"
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/*
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* We have some experimental code here to allow for constant velocity
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* movement of actors along the bezier path, this macro enables it.
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*/
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#undef CBZ_L2T_INTERPOLATION
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/****************************************************************************
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* ClutterBezier -- represenation of a cubic bezier curve *
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* (private; a building block for the public bspline object) *
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****************************************************************************/
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/*
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* The t parameter of the bezier is from interval <0,1>, so we can use
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* 14.18 format and special multiplication functions that preserve
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* more of the least significant bits but would overflow if the value
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* is > 1
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*/
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#define CBZ_T_Q 18
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#define CBZ_T_ONE (1 << CBZ_T_Q)
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#define CBZ_T_MUL(x,y) ((((x) >> 3) * ((y) >> 3)) >> 12)
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#define CBZ_T_POW2(x) CBZ_T_MUL (x, x)
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#define CBZ_T_POW3(x) CBZ_T_MUL (CBZ_T_POW2 (x), x)
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#define CBZ_T_DIV(x,y) ((((x) << 9)/(y)) << 9)
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/*
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* Constants for sampling of the bezier
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*/
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#define CBZ_T_SAMPLES 128
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#define CBZ_T_STEP (CBZ_T_ONE / CBZ_T_SAMPLES)
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#define CBZ_L_STEP (CBZ_T_ONE / CBZ_T_SAMPLES)
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typedef gint32 _FixedT;
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/*
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* This is a private type representing a single cubic bezier
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*/
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struct _ClutterBezier
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{
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/*
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* bezier coefficients -- these are calculated using multiplication and
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* addition from integer input, so these are also integers
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*/
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gint ax;
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gint bx;
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gint cx;
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gint dx;
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gint ay;
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gint by;
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gint cy;
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gint dy;
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/* length of the bezier */
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guint length;
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#ifdef CBZ_L2T_INTERPOLATION
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/*
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* coefficients for the L -> t bezier; these are calculated from fixed
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* point input, and more specifically numbers that have been normalised
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* to fit <0,1>, so these are also fixed point, and we can used the
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* _FixedT type here.
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*/
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_FixedT La;
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_FixedT Lb;
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_FixedT Lc;
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/* _FixedT Ld; == 0 */
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#endif
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};
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ClutterBezier *
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_clutter_bezier_new (void)
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{
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return g_slice_new0 (ClutterBezier);
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}
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void
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_clutter_bezier_free (ClutterBezier * b)
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{
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if (G_LIKELY (b))
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{
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g_slice_free (ClutterBezier, b);
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}
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}
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ClutterBezier *
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_clutter_bezier_clone_and_move (const ClutterBezier *b, gint x, gint y)
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{
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ClutterBezier * b2 = _clutter_bezier_new ();
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memcpy (b2, b, sizeof (ClutterBezier));
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b2->dx += x;
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b2->dy += y;
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return b2;
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}
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#ifdef CBZ_L2T_INTERPOLATION
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/*
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* L is relative advance along the bezier curve from interval <0,1>
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*/
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static _FixedT
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_clutter_bezier_L2t (const ClutterBezier *b, _FixedT L)
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{
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_FixedT t = CBZ_T_MUL (b->La, CBZ_T_POW3(L))
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+ CBZ_T_MUL (b->Lb, CBZ_T_POW2(L))
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+ CBZ_T_MUL (b->Lc, L);
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if (t > CBZ_T_ONE)
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t = CBZ_T_ONE;
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else if (t < 0)
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t = 0;
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return t;
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}
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#endif
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static gint
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_clutter_bezier_t2x (const ClutterBezier * b, _FixedT t)
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{
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/*
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* NB -- the int coefficients can be at most 8192 for the multiplication
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* to work in this fashion due to the limits of the 14.18 fixed.
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*/
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return ((b->ax*CBZ_T_POW3(t) + b->bx*CBZ_T_POW2(t) + b->cx*t) >> CBZ_T_Q)
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+ b->dx;
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}
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static gint
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_clutter_bezier_t2y (const ClutterBezier * b, _FixedT t)
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{
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/*
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* NB -- the int coefficients can be at most 8192 for the multiplication
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* to work in this fashion due to the limits of the 14.18 fixed.
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*/
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return ((b->ay*CBZ_T_POW3(t) + b->by*CBZ_T_POW2(t) + b->cy*t) >> CBZ_T_Q)
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+ b->dy;
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}
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/*
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* Advances along the bezier to relative length L and returns the coordinances
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* in knot
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*/
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void
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_clutter_bezier_advance (const ClutterBezier *b, gint L, ClutterKnot * knot)
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{
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#ifdef CBZ_L2T_INTERPOLATION
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_FixedT t = clutter_bezier_L2t (b, L);
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#else
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_FixedT t = L;
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#endif
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knot->x = _clutter_bezier_t2x (b, t);
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knot->y = _clutter_bezier_t2y (b, t);
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CLUTTER_NOTE (MISC, "advancing to relative pt %f: t %f, {%d,%d}",
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(double) L / (double) CBZ_T_ONE,
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(double) t / (double) CBZ_T_ONE,
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knot->x, knot->y);
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}
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void
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_clutter_bezier_init (ClutterBezier *b,
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gint x_0, gint y_0,
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gint x_1, gint y_1,
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gint x_2, gint y_2,
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gint x_3, gint y_3)
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{
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_FixedT t;
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int i;
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int xp = x_0;
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int yp = y_0;
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_FixedT length [CBZ_T_SAMPLES + 1];
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#ifdef CBZ_L2T_INTERPOLATION
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int j, k;
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_FixedT L;
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_FixedT t_equalized [CBZ_T_SAMPLES + 1];
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#endif
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#if 0
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g_debug ("Initializing bezier at {{%d,%d},{%d,%d},{%d,%d},{%d,%d}}",
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x0, y0, x1, y1, x2, y2, x3, y3);
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#endif
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b->dx = x_0;
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b->dy = y_0;
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b->cx = 3 * (x_1 - x_0);
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b->cy = 3 * (y_1 - y_0);
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b->bx = 3 * (x_2 - x_1) - b->cx;
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b->by = 3 * (y_2 - y_1) - b->cy;
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b->ax = x_3 - 3 * x_2 + 3 * x_1 - x_0;
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b->ay = y_3 - 3 * y_2 + 3 * y_1 - y_0;
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#if 0
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g_debug ("Cooeficients {{%d,%d},{%d,%d},{%d,%d},{%d,%d}}",
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b->ax, b->ay, b->bx, b->by, b->cx, b->cy, b->dx, b->dy);
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#endif
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/*
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* Because of the way we do the multiplication in bezeir_t2x,y
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* these coefficients need to be at most 0x1fff; this should be the case,
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* I think, but have added this warning to catch any problems -- if it
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* triggers, we need to change those two functions a bit.
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*/
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if (b->ax > 0x1fff || b->bx > 0x1fff || b->cx > 0x1fff)
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g_warning ("Calculated coefficents will result in multiplication "
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"overflow in clutter_bezier_t2x and clutter_bezier_t2y.");
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/*
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* Sample the bezier with CBZ_T_SAMPLES and calculate length at
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* each point.
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*
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* We are working with integers here, so we use the fast sqrti function.
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*/
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length[0] = 0;
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for (t = CBZ_T_STEP, i = 1; i <= CBZ_T_SAMPLES; ++i, t += CBZ_T_STEP)
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{
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int x = _clutter_bezier_t2x (b, t);
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int y = _clutter_bezier_t2y (b, t);
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guint l = cogl_sqrti ((y - yp)*(y - yp) + (x - xp)*(x - xp));
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l += length[i-1];
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length[i] = l;
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xp = x;
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yp = y;
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}
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b->length = length[CBZ_T_SAMPLES];
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#if 0
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g_debug ("length %d", b->length);
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#endif
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#ifdef CBZ_L2T_INTERPOLATION
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/*
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* Now normalize the length values, converting them into _FixedT
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*/
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for (i = 0; i <= CBZ_T_SAMPLES; ++i)
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{
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length[i] = (length[i] << CBZ_T_Q) / b->length;
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}
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/*
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* Now generate a L -> t table such that the L will equidistant
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* over <0,1>
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*/
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t_equalized[0] = 0;
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for (i = 1, j = 1, L = CBZ_L_STEP; i < CBZ_T_SAMPLES; ++i, L += CBZ_L_STEP)
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{
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_FixedT l1, l2;
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_FixedT d1, d2, d;
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_FixedT t1, t2;
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/* find the band for our L */
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for (k = j; k < CBZ_T_SAMPLES; ++k)
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{
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if (L < length[k])
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break;
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}
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/*
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* Now we know that L is from (length[k-1],length[k]>
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* We remember k-1 in order not to have to iterate over the
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* whole length array in the next iteration of the main loop
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*/
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j = k - 1;
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/*
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* Now interpolate equlised t as a weighted average
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*/
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l1 = length[k-1];
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l2 = length[k];
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d1 = l2 - L;
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d2 = L - l1;
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d = l2 - l1;
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t1 = (k - 1) * CBZ_T_STEP;
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t2 = k * CBZ_T_STEP;
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t_equalized[i] = (t1*d1 + t2*d2)/d;
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if (t_equalized[i] < t_equalized[i-1])
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g_debug ("wrong t: L %f, l1 %f, l2 %f, t1 %f, t2 %f",
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(double) (L)/(double)CBZ_T_ONE,
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(double) (l1)/(double)CBZ_T_ONE,
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(double) (l2)/(double)CBZ_T_ONE,
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(double) (t1)/(double)CBZ_T_ONE,
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(double) (t2)/(double)CBZ_T_ONE);
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}
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t_equalized[CBZ_T_SAMPLES] = CBZ_T_ONE;
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/* We now fit a bezier -- at this stage, do a single fit through our values
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* at 0, 1/3, 2/3 and 1
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*
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* FIXME -- do we need to use a better fitting approach to choose the best
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* beziere. The actual curve we acquire this way is not too bad shapwise,
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* but (probably due to rounding errors) the resulting curve no longer
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* satisfies the necessary condition that for L2 > L1, t2 > t1, which
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* causes oscilation.
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*/
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#if 0
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/*
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* These are the control points we use to calculate the curve coefficients
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* for bezier t(L); these are not needed directly, but are implied in the
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* calculations below.
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*
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* (p0 is 0,0, and p3 is 1,1)
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*/
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p1 = (18 * t_equalized[CBZ_T_SAMPLES/3] -
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9 * t_equalized[2*CBZ_T_SAMPLES/3] +
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2 << CBZ_T_Q) / 6;
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p2 = (18 * t_equalized[2*CBZ_T_SAMPLES/3] -
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9 * t_equalized[CBZ_T_SAMPLES/3] -
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(5 << CBZ_T_Q)) / 6;
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#endif
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b->Lc = (18 * t_equalized[CBZ_T_SAMPLES/3] -
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9 * t_equalized[2*CBZ_T_SAMPLES/3] +
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(2 << CBZ_T_Q)) >> 1;
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b->Lb = (36 * t_equalized[2*CBZ_T_SAMPLES/3] -
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45 * t_equalized[CBZ_T_SAMPLES/3] -
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(9 << CBZ_T_Q)) >> 1;
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b->La = ((27 * (t_equalized[CBZ_T_SAMPLES/3] -
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t_equalized[2*CBZ_T_SAMPLES/3]) +
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(7 << CBZ_T_Q)) >> 1) + CBZ_T_ONE;
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g_debug ("t(1/3) %f, t(2/3) %f",
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(double)t_equalized[CBZ_T_SAMPLES/3]/(double)CBZ_T_ONE,
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(double)t_equalized[2*CBZ_T_SAMPLES/3]/(double)CBZ_T_ONE);
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g_debug ("L -> t coefficients: %f, %f, %f",
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(double)b->La/(double)CBZ_T_ONE,
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(double)b->Lb/(double)CBZ_T_ONE,
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(double)b->Lc/(double)CBZ_T_ONE);
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/*
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* For debugging, you can load these values into a spreadsheet and graph
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* them to see how well the approximation matches the data
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*/
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for (i = 0; i < CBZ_T_SAMPLES; ++i)
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{
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g_print ("%f, %f, %f\n",
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(double)(i*CBZ_T_STEP)/(double)CBZ_T_ONE,
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(double)(t_equalized[i])/(double)CBZ_T_ONE,
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(double)(clutter_bezier_L2t(b,i*CBZ_T_STEP))/(double)CBZ_T_ONE);
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}
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#endif
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}
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/*
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* Moves a control point at indx to location represented by knot
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*/
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void
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_clutter_bezier_adjust (ClutterBezier * b, ClutterKnot * knot, guint indx)
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{
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guint x[4], y[4];
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g_assert (indx < 4);
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x[0] = b->dx;
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y[0] = b->dy;
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x[1] = b->cx / 3 + x[0];
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y[1] = b->cy / 3 + y[0];
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x[2] = b->bx / 3 + b->cx + x[1];
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y[2] = b->by / 3 + b->cy + y[1];
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x[3] = b->ax + x[0] + b->cx + b->bx;
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y[3] = b->ay + y[0] + b->cy + b->by;
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x[indx] = knot->x;
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y[indx] = knot->y;
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_clutter_bezier_init (b, x[0], y[0], x[1], y[1], x[2], y[2], x[3], y[3]);
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}
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guint
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_clutter_bezier_get_length (const ClutterBezier *b)
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{
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return b->length;
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}
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