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729 lines
24 KiB
C
729 lines
24 KiB
C
/* Libart_LGPL - library of basic graphic primitives
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* Copyright (C) 1998-2000 Raph Levien
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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 Library 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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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/* The spiffy antialiased renderer for sorted vector paths. */
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#include <math.h>
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#include "art_misc.h"
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#include "art_rect.h"
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#include "art_svp.h"
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#include "art_svp_render_aa.h"
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struct _ArtSVPRenderAAIter {
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const ArtSVP *svp;
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int x0, x1;
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int y;
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int seg_ix;
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int *active_segs;
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int n_active_segs;
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int *cursor;
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double *seg_x;
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double *seg_dx;
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ArtSVPRenderAAStep *steps;
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int n_steps_max;
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};
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static void
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art_svp_render_insert_active (int i, int *active_segs, int n_active_segs,
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double *seg_x, double *seg_dx)
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{
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int j;
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double x;
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int tmp1, tmp2;
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/* this is a cheap hack to get ^'s sorted correctly */
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x = seg_x[i] + 0.001 * seg_dx[i];
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for (j = 0; j < n_active_segs && seg_x[active_segs[j]] < x; j++);
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tmp1 = i;
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while (j < n_active_segs)
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{
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tmp2 = active_segs[j];
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active_segs[j] = tmp1;
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tmp1 = tmp2;
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j++;
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}
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active_segs[j] = tmp1;
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}
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static void
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art_svp_render_delete_active (int *active_segs, int j, int n_active_segs)
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{
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int k;
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for (k = j; k < n_active_segs; k++)
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active_segs[k] = active_segs[k + 1];
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}
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static int
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art_svp_render_step_compare (const void *s1, const void *s2)
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{
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const ArtSVPRenderAAStep *step1 = s1;
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const ArtSVPRenderAAStep *step2 = s2;
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return step1->x - step2->x;
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}
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#define EPSILON 1e-6
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/* Render the sorted vector path in the given rectangle, antialiased.
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This interface uses a callback for the actual pixel rendering. The
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callback is called y1 - y0 times (once for each scan line). The y
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coordinate is given as an argument for convenience (it could be
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stored in the callback's private data and incremented on each
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call).
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The rendered polygon is represented in a semi-runlength format: a
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start value and a sequence of "steps". Each step has an x
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coordinate and a value delta. The resulting value at position x is
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equal to the sum of the start value and all step delta values for
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which the step x coordinate is less than or equal to x. An
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efficient algorithm will traverse the steps left to right, keeping
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a running sum.
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All x coordinates in the steps are guaranteed to be x0 <= x < x1.
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(This guarantee is a change from the gfonted vpaar renderer, and is
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designed to simplify the callback).
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The value 0x8000 represents 0% coverage by the polygon, while
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0xff8000 represents 100% coverage. This format is designed so that
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>> 16 results in a standard 0x00..0xff value range, with nice
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rounding.
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Status of this routine:
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Basic correctness: OK
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Numerical stability: pretty good, although probably not
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bulletproof.
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Speed: Needs more aggressive culling of bounding boxes. Can
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probably speed up the [x0,x1) clipping of step values. Can do more
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of the step calculation in fixed point.
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Precision: No known problems, although it should be tested
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thoroughly, especially for symmetry.
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*/
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ArtSVPRenderAAIter *
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art_svp_render_aa_iter (const ArtSVP *svp,
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int x0, int y0, int x1, int y1)
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{
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ArtSVPRenderAAIter *iter = art_new (ArtSVPRenderAAIter, 1);
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iter->svp = svp;
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iter->y = y0;
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iter->x0 = x0;
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iter->x1 = x1;
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iter->seg_ix = 0;
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iter->active_segs = art_new (int, svp->n_segs);
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iter->cursor = art_new (int, svp->n_segs);
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iter->seg_x = art_new (double, svp->n_segs);
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iter->seg_dx = art_new (double, svp->n_segs);
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iter->n_steps_max = 256;
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iter->steps = art_new (ArtSVPRenderAAStep, iter->n_steps_max);
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iter->n_active_segs = 0;
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return iter;
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}
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void
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art_svp_render_aa_iter_step (ArtSVPRenderAAIter *iter, int *p_start,
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ArtSVPRenderAAStep **p_steps, int *p_n_steps)
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{
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const ArtSVP *svp = iter->svp;
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int *active_segs = iter->active_segs;
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int n_active_segs = iter->n_active_segs;
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int *cursor = iter->cursor;
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double *seg_x = iter->seg_x;
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double *seg_dx = iter->seg_dx;
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int i = iter->seg_ix;
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int j;
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int x0 = iter->x0;
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int x1 = iter->x1;
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int y = iter->y;
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int seg_index;
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int x;
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ArtSVPRenderAAStep *steps = iter->steps;
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int n_steps;
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int n_steps_max = iter->n_steps_max;
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double y_top, y_bot;
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double x_top, x_bot;
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double x_min, x_max;
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int ix_min, ix_max;
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double delta; /* delta should be int too? */
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int last, this;
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int xdelta;
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double rslope, drslope;
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int start;
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const ArtSVPSeg *seg;
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int curs;
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double dy;
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/* insert new active segments */
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for (; i < svp->n_segs && svp->segs[i].bbox.y0 < y + 1; i++)
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{
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if (svp->segs[i].bbox.y1 > y &&
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svp->segs[i].bbox.x0 < x1)
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{
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seg = &svp->segs[i];
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/* move cursor to topmost vector which overlaps [y,y+1) */
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for (curs = 0; seg->points[curs + 1].y < y; curs++);
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cursor[i] = curs;
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dy = seg->points[curs + 1].y - seg->points[curs].y;
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if (fabs (dy) >= EPSILON)
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seg_dx[i] = (seg->points[curs + 1].x - seg->points[curs].x) /
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dy;
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else
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seg_dx[i] = 1e12;
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seg_x[i] = seg->points[curs].x +
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(y - seg->points[curs].y) * seg_dx[i];
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art_svp_render_insert_active (i, active_segs, n_active_segs++,
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seg_x, seg_dx);
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}
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}
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n_steps = 0;
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/* render the runlengths, advancing and deleting as we go */
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start = 0x8000;
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for (j = 0; j < n_active_segs; j++)
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{
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seg_index = active_segs[j];
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seg = &svp->segs[seg_index];
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curs = cursor[seg_index];
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while (curs != seg->n_points - 1 &&
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seg->points[curs].y < y + 1)
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{
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y_top = y;
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if (y_top < seg->points[curs].y)
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y_top = seg->points[curs].y;
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y_bot = y + 1;
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if (y_bot > seg->points[curs + 1].y)
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y_bot = seg->points[curs + 1].y;
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if (y_top != y_bot) {
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delta = (seg->dir ? 16711680.0 : -16711680.0) *
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(y_bot - y_top);
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x_top = seg_x[seg_index] + (y_top - y) * seg_dx[seg_index];
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x_bot = seg_x[seg_index] + (y_bot - y) * seg_dx[seg_index];
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if (x_top < x_bot)
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{
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x_min = x_top;
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x_max = x_bot;
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}
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else
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{
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x_min = x_bot;
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x_max = x_top;
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}
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ix_min = floor (x_min);
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ix_max = floor (x_max);
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if (ix_min >= x1)
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{
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/* skip; it starts to the right of the render region */
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}
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else if (ix_max < x0)
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/* it ends to the left of the render region */
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start += delta;
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else if (ix_min == ix_max)
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{
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/* case 1, antialias a single pixel */
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if (n_steps + 2 > n_steps_max)
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{
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art_expand (steps, ArtSVPRenderAAStep, n_steps_max);
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iter->steps = steps;
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iter->n_steps_max = n_steps_max;
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}
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xdelta = (ix_min + 1 - (x_min + x_max) * 0.5) * delta;
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steps[n_steps].x = ix_min;
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steps[n_steps].delta = xdelta;
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n_steps++;
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if (ix_min + 1 < x1)
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{
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xdelta = delta - xdelta;
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steps[n_steps].x = ix_min + 1;
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steps[n_steps].delta = xdelta;
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n_steps++;
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}
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}
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else
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{
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/* case 2, antialias a run */
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if (n_steps + ix_max + 2 - ix_min > n_steps_max)
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{
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do
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n_steps_max <<= 1;
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while (n_steps + ix_max + 2 - ix_min > n_steps_max);
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steps = art_renew (steps, ArtSVPRenderAAStep,
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n_steps_max);
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iter->steps = steps;
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iter->n_steps_max = n_steps_max;
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}
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rslope = 1.0 / fabs (seg_dx[seg_index]);
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drslope = delta * rslope;
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last =
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drslope * 0.5 *
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(ix_min + 1 - x_min) * (ix_min + 1 - x_min);
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xdelta = last;
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if (ix_min >= x0)
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{
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steps[n_steps].x = ix_min;
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steps[n_steps].delta = last;
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n_steps++;
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x = ix_min + 1;
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}
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else
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{
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start += last;
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x = x0;
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}
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for (; x < x1 && x < ix_max; x++)
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{
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this = (seg->dir ? 16711680.0 : -16711680.0) * rslope *
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(x + 0.5 - x_min);
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xdelta = this - last;
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last = this;
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steps[n_steps].x = x;
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steps[n_steps].delta = xdelta;
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n_steps++;
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}
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if (x < x1)
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{
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this =
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delta * (1 - 0.5 *
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(x_max - ix_max) * (x_max - ix_max) *
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rslope);
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xdelta = this - last;
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last = this;
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steps[n_steps].x = ix_max;
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steps[n_steps].delta = xdelta;
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n_steps++;
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if (x + 1 < x1)
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{
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xdelta = delta - last;
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steps[n_steps].x = ix_max + 1;
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steps[n_steps].delta = xdelta;
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n_steps++;
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}
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}
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}
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}
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curs++;
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if (curs != seg->n_points - 1 &&
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seg->points[curs].y < y + 1)
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{
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dy = seg->points[curs + 1].y - seg->points[curs].y;
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if (fabs (dy) >= EPSILON)
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seg_dx[seg_index] = (seg->points[curs + 1].x -
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seg->points[curs].x) / dy;
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else
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seg_dx[seg_index] = 1e12;
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seg_x[seg_index] = seg->points[curs].x +
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(y - seg->points[curs].y) * seg_dx[seg_index];
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}
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/* break here, instead of duplicating predicate in while? */
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}
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if (seg->points[curs].y >= y + 1)
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{
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curs--;
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cursor[seg_index] = curs;
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seg_x[seg_index] += seg_dx[seg_index];
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}
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else
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{
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art_svp_render_delete_active (active_segs, j--,
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--n_active_segs);
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}
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}
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/* sort the steps */
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if (n_steps)
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qsort (steps, n_steps, sizeof(ArtSVPRenderAAStep),
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art_svp_render_step_compare);
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*p_start = start;
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*p_steps = steps;
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*p_n_steps = n_steps;
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iter->seg_ix = i;
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iter->n_active_segs = n_active_segs;
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iter->y++;
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}
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void
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art_svp_render_aa_iter_done (ArtSVPRenderAAIter *iter)
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{
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art_free (iter->steps);
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art_free (iter->seg_dx);
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art_free (iter->seg_x);
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art_free (iter->cursor);
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art_free (iter->active_segs);
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art_free (iter);
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}
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#if 0
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/**
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* art_svp_render_aa: Render SVP antialiased.
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* @svp: The #ArtSVP to render.
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* @x0: Left coordinate of destination rectangle.
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* @y0: Top coordinate of destination rectangle.
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* @x1: Right coordinate of destination rectangle.
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* @y1: Bottom coordinate of destination rectangle.
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* @callback: The callback which actually paints the pixels.
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* @callback_data: Private data for @callback.
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*
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* Renders the sorted vector path in the given rectangle, antialiased.
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*
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* This interface uses a callback for the actual pixel rendering. The
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* callback is called @y1 - @y0 times (once for each scan line). The y
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* coordinate is given as an argument for convenience (it could be
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* stored in the callback's private data and incremented on each
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* call).
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*
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* The rendered polygon is represented in a semi-runlength format: a
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* start value and a sequence of "steps". Each step has an x
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* coordinate and a value delta. The resulting value at position x is
|
|
* equal to the sum of the start value and all step delta values for
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* which the step x coordinate is less than or equal to x. An
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* efficient algorithm will traverse the steps left to right, keeping
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* a running sum.
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*
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* All x coordinates in the steps are guaranteed to be @x0 <= x < @x1.
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* (This guarantee is a change from the gfonted vpaar renderer from
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* which this routine is derived, and is designed to simplify the
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* callback).
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*
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* The value 0x8000 represents 0% coverage by the polygon, while
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* 0xff8000 represents 100% coverage. This format is designed so that
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* >> 16 results in a standard 0x00..0xff value range, with nice
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* rounding.
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*
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**/
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void
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art_svp_render_aa (const ArtSVP *svp,
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int x0, int y0, int x1, int y1,
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void (*callback) (void *callback_data,
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int y,
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int start,
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ArtSVPRenderAAStep *steps, int n_steps),
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void *callback_data)
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{
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int *active_segs;
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int n_active_segs;
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int *cursor;
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double *seg_x;
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double *seg_dx;
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int i, j;
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int y;
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int seg_index;
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int x;
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ArtSVPRenderAAStep *steps;
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int n_steps;
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int n_steps_max;
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double y_top, y_bot;
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double x_top, x_bot;
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double x_min, x_max;
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int ix_min, ix_max;
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double delta; /* delta should be int too? */
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int last, this;
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int xdelta;
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double rslope, drslope;
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int start;
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const ArtSVPSeg *seg;
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int curs;
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double dy;
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active_segs = art_new (int, svp->n_segs);
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cursor = art_new (int, svp->n_segs);
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seg_x = art_new (double, svp->n_segs);
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seg_dx = art_new (double, svp->n_segs);
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n_steps_max = 256;
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steps = art_new (ArtSVPRenderAAStep, n_steps_max);
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n_active_segs = 0;
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i = 0;
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/* iterate through the scanlines */
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for (y = y0; y < y1; y++)
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{
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/* insert new active segments */
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for (; i < svp->n_segs && svp->segs[i].bbox.y0 < y + 1; i++)
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{
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if (svp->segs[i].bbox.y1 > y &&
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svp->segs[i].bbox.x0 < x1)
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{
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seg = &svp->segs[i];
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/* move cursor to topmost vector which overlaps [y,y+1) */
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for (curs = 0; seg->points[curs + 1].y < y; curs++);
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cursor[i] = curs;
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dy = seg->points[curs + 1].y - seg->points[curs].y;
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if (fabs (dy) >= EPSILON)
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seg_dx[i] = (seg->points[curs + 1].x - seg->points[curs].x) /
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dy;
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else
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seg_dx[i] = 1e12;
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seg_x[i] = seg->points[curs].x +
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(y - seg->points[curs].y) * seg_dx[i];
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art_svp_render_insert_active (i, active_segs, n_active_segs++,
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seg_x, seg_dx);
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|
}
|
|
}
|
|
|
|
n_steps = 0;
|
|
|
|
/* render the runlengths, advancing and deleting as we go */
|
|
start = 0x8000;
|
|
|
|
for (j = 0; j < n_active_segs; j++)
|
|
{
|
|
seg_index = active_segs[j];
|
|
seg = &svp->segs[seg_index];
|
|
curs = cursor[seg_index];
|
|
while (curs != seg->n_points - 1 &&
|
|
seg->points[curs].y < y + 1)
|
|
{
|
|
y_top = y;
|
|
if (y_top < seg->points[curs].y)
|
|
y_top = seg->points[curs].y;
|
|
y_bot = y + 1;
|
|
if (y_bot > seg->points[curs + 1].y)
|
|
y_bot = seg->points[curs + 1].y;
|
|
if (y_top != y_bot) {
|
|
delta = (seg->dir ? 16711680.0 : -16711680.0) *
|
|
(y_bot - y_top);
|
|
x_top = seg_x[seg_index] + (y_top - y) * seg_dx[seg_index];
|
|
x_bot = seg_x[seg_index] + (y_bot - y) * seg_dx[seg_index];
|
|
if (x_top < x_bot)
|
|
{
|
|
x_min = x_top;
|
|
x_max = x_bot;
|
|
}
|
|
else
|
|
{
|
|
x_min = x_bot;
|
|
x_max = x_top;
|
|
}
|
|
ix_min = floor (x_min);
|
|
ix_max = floor (x_max);
|
|
if (ix_min >= x1)
|
|
{
|
|
/* skip; it starts to the right of the render region */
|
|
}
|
|
else if (ix_max < x0)
|
|
/* it ends to the left of the render region */
|
|
start += delta;
|
|
else if (ix_min == ix_max)
|
|
{
|
|
/* case 1, antialias a single pixel */
|
|
if (n_steps + 2 > n_steps_max)
|
|
art_expand (steps, ArtSVPRenderAAStep, n_steps_max);
|
|
xdelta = (ix_min + 1 - (x_min + x_max) * 0.5) * delta;
|
|
steps[n_steps].x = ix_min;
|
|
steps[n_steps].delta = xdelta;
|
|
n_steps++;
|
|
if (ix_min + 1 < x1)
|
|
{
|
|
xdelta = delta - xdelta;
|
|
steps[n_steps].x = ix_min + 1;
|
|
steps[n_steps].delta = xdelta;
|
|
n_steps++;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* case 2, antialias a run */
|
|
if (n_steps + ix_max + 2 - ix_min > n_steps_max)
|
|
{
|
|
do
|
|
n_steps_max <<= 1;
|
|
while (n_steps + ix_max + 2 - ix_min > n_steps_max);
|
|
steps = art_renew (steps, ArtSVPRenderAAStep,
|
|
n_steps_max);
|
|
}
|
|
rslope = 1.0 / fabs (seg_dx[seg_index]);
|
|
drslope = delta * rslope;
|
|
last =
|
|
drslope * 0.5 *
|
|
(ix_min + 1 - x_min) * (ix_min + 1 - x_min);
|
|
xdelta = last;
|
|
if (ix_min >= x0)
|
|
{
|
|
steps[n_steps].x = ix_min;
|
|
steps[n_steps].delta = last;
|
|
n_steps++;
|
|
x = ix_min + 1;
|
|
}
|
|
else
|
|
{
|
|
start += last;
|
|
x = x0;
|
|
}
|
|
for (; x < x1 && x < ix_max; x++)
|
|
{
|
|
this = (seg->dir ? 16711680.0 : -16711680.0) * rslope *
|
|
(x + 0.5 - x_min);
|
|
xdelta = this - last;
|
|
last = this;
|
|
steps[n_steps].x = x;
|
|
steps[n_steps].delta = xdelta;
|
|
n_steps++;
|
|
}
|
|
if (x < x1)
|
|
{
|
|
this =
|
|
delta * (1 - 0.5 *
|
|
(x_max - ix_max) * (x_max - ix_max) *
|
|
rslope);
|
|
xdelta = this - last;
|
|
last = this;
|
|
steps[n_steps].x = ix_max;
|
|
steps[n_steps].delta = xdelta;
|
|
n_steps++;
|
|
if (x + 1 < x1)
|
|
{
|
|
xdelta = delta - last;
|
|
steps[n_steps].x = ix_max + 1;
|
|
steps[n_steps].delta = xdelta;
|
|
n_steps++;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
curs++;
|
|
if (curs != seg->n_points - 1 &&
|
|
seg->points[curs].y < y + 1)
|
|
{
|
|
dy = seg->points[curs + 1].y - seg->points[curs].y;
|
|
if (fabs (dy) >= EPSILON)
|
|
seg_dx[seg_index] = (seg->points[curs + 1].x -
|
|
seg->points[curs].x) / dy;
|
|
else
|
|
seg_dx[seg_index] = 1e12;
|
|
seg_x[seg_index] = seg->points[curs].x +
|
|
(y - seg->points[curs].y) * seg_dx[seg_index];
|
|
}
|
|
/* break here, instead of duplicating predicate in while? */
|
|
}
|
|
if (seg->points[curs].y >= y + 1)
|
|
{
|
|
curs--;
|
|
cursor[seg_index] = curs;
|
|
seg_x[seg_index] += seg_dx[seg_index];
|
|
}
|
|
else
|
|
{
|
|
art_svp_render_delete_active (active_segs, j--,
|
|
--n_active_segs);
|
|
}
|
|
}
|
|
|
|
/* sort the steps */
|
|
if (n_steps)
|
|
qsort (steps, n_steps, sizeof(ArtSVPRenderAAStep),
|
|
art_svp_render_step_compare);
|
|
|
|
(*callback) (callback_data, y, start, steps, n_steps);
|
|
}
|
|
|
|
art_free (steps);
|
|
|
|
art_free (seg_dx);
|
|
art_free (seg_x);
|
|
art_free (cursor);
|
|
art_free (active_segs);
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* art_svp_render_aa: Render SVP antialiased.
|
|
* @svp: The #ArtSVP to render.
|
|
* @x0: Left coordinate of destination rectangle.
|
|
* @y0: Top coordinate of destination rectangle.
|
|
* @x1: Right coordinate of destination rectangle.
|
|
* @y1: Bottom coordinate of destination rectangle.
|
|
* @callback: The callback which actually paints the pixels.
|
|
* @callback_data: Private data for @callback.
|
|
*
|
|
* Renders the sorted vector path in the given rectangle, antialiased.
|
|
*
|
|
* This interface uses a callback for the actual pixel rendering. The
|
|
* callback is called @y1 - @y0 times (once for each scan line). The y
|
|
* coordinate is given as an argument for convenience (it could be
|
|
* stored in the callback's private data and incremented on each
|
|
* call).
|
|
*
|
|
* The rendered polygon is represented in a semi-runlength format: a
|
|
* start value and a sequence of "steps". Each step has an x
|
|
* coordinate and a value delta. The resulting value at position x is
|
|
* equal to the sum of the start value and all step delta values for
|
|
* which the step x coordinate is less than or equal to x. An
|
|
* efficient algorithm will traverse the steps left to right, keeping
|
|
* a running sum.
|
|
*
|
|
* All x coordinates in the steps are guaranteed to be @x0 <= x < @x1.
|
|
* (This guarantee is a change from the gfonted vpaar renderer from
|
|
* which this routine is derived, and is designed to simplify the
|
|
* callback).
|
|
*
|
|
* The value 0x8000 represents 0% coverage by the polygon, while
|
|
* 0xff8000 represents 100% coverage. This format is designed so that
|
|
* >> 16 results in a standard 0x00..0xff value range, with nice
|
|
* rounding.
|
|
*
|
|
**/
|
|
void
|
|
art_svp_render_aa (const ArtSVP *svp,
|
|
int x0, int y0, int x1, int y1,
|
|
void (*callback) (void *callback_data,
|
|
int y,
|
|
int start,
|
|
ArtSVPRenderAAStep *steps, int n_steps),
|
|
void *callback_data)
|
|
{
|
|
ArtSVPRenderAAIter *iter;
|
|
int y;
|
|
int start;
|
|
ArtSVPRenderAAStep *steps;
|
|
int n_steps;
|
|
|
|
iter = art_svp_render_aa_iter (svp, x0, y0, x1, y1);
|
|
|
|
for (y = y0; y < y1; y++)
|
|
{
|
|
art_svp_render_aa_iter_step (iter, &start, &steps, &n_steps);
|
|
(*callback) (callback_data, y, start, steps, n_steps);
|
|
}
|
|
|
|
art_svp_render_aa_iter_done (iter);
|
|
}
|