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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009 Intel Corporation.
*
* 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 <http://www.gnu.org/licenses/>.
*
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "math.h"
#include "cogl.h"
#include "cogl-util.h"
#include "cogl-internal.h"
#include "cogl-spans.h"
void
_cogl_span_iter_update (CoglSpanIter *iter)
{
/* Pick current span */
iter->span = &iter->spans[iter->index];
/* Offset next position by span size */
iter->next_pos = iter->pos + iter->span->size - iter->span->waste;
/* Check if span intersects the area to cover */
if (iter->next_pos <= iter->cover_start ||
iter->pos >= iter->cover_end)
{
/* Intersection undefined */
iter->intersects = FALSE;
return;
}
iter->intersects = TRUE;
/* Clip start position to coverage area */
if (iter->pos < iter->cover_start)
iter->intersect_start = iter->cover_start;
else
iter->intersect_start = iter->pos;
/* Clip end position to coverage area */
if (iter->next_pos > iter->cover_end)
iter->intersect_end = iter->cover_end;
else
iter->intersect_end = iter->next_pos;
}
void
_cogl_span_iter_begin (CoglSpanIter *iter,
const CoglSpan *spans,
int n_spans,
float normalize_factor,
float cover_start,
float cover_end,
CoglPipelineWrapMode wrap_mode)
{
/* XXX: If CLAMP_TO_EDGE needs to be emulated then it needs to be
* done at a higher level than here... */
_COGL_RETURN_IF_FAIL (wrap_mode == COGL_PIPELINE_WRAP_MODE_REPEAT ||
wrap_mode == COGL_PIPELINE_WRAP_MODE_MIRRORED_REPEAT);
iter->span = NULL;
iter->spans = spans;
iter->n_spans = n_spans;
/* We always iterate in a positive direction from the origin. If
* iter->flipped == TRUE that means whoever is using this API should
* interpreted the current span as extending in the opposite direction. I.e.
* it extends to the left if iterating the X axis, or up if the Y axis. */
if (cover_start > cover_end)
{
float tmp = cover_start;
cover_start = cover_end;
cover_end = tmp;
iter->flipped = TRUE;
}
else
iter->flipped = FALSE;
/* The texture spans cover the normalized texture coordinate space ranging
* from [0,1] but to help support repeating of sliced textures we allow
* iteration of any range so we need to relate the start of the range to the
* nearest point equivalent to 0.
*/
if (normalize_factor != 1.0)
{
float cover_start_normalized = cover_start / normalize_factor;
iter->origin = floorf (cover_start_normalized) * normalize_factor;
}
else
iter->origin = floorf (cover_start);
iter->wrap_mode = wrap_mode;
if (wrap_mode == COGL_PIPELINE_WRAP_MODE_REPEAT)
iter->index = 0;
else if (wrap_mode == COGL_PIPELINE_WRAP_MODE_MIRRORED_REPEAT)
{
if ((int)iter->origin % 2)
{
iter->index = iter->n_spans - 1;
iter->mirror_direction = -1;
iter->flipped = !iter->flipped;
}
else
{
iter->index = 0;
iter->mirror_direction = 1;
}
}
else
g_warn_if_reached ();
iter->cover_start = cover_start;
iter->cover_end = cover_end;
iter->pos = iter->origin;
/* Update intersection */
_cogl_span_iter_update (iter);
while (iter->next_pos <= iter->cover_start)
_cogl_span_iter_next (iter);
}
void
_cogl_span_iter_next (CoglSpanIter *iter)
{
/* Move current position */
iter->pos = iter->next_pos;
if (iter->wrap_mode == COGL_PIPELINE_WRAP_MODE_REPEAT)
iter->index = (iter->index + 1) % iter->n_spans;
else if (iter->wrap_mode == COGL_PIPELINE_WRAP_MODE_MIRRORED_REPEAT)
{
iter->index += iter->mirror_direction;
if (iter->index == iter->n_spans || iter->index == -1)
{
iter->mirror_direction = -iter->mirror_direction;
iter->index += iter->mirror_direction;
iter->flipped = !iter->flipped;
}
}
else
g_warn_if_reached ();
/* Update intersection */
_cogl_span_iter_update (iter);
}
gboolean
_cogl_span_iter_end (CoglSpanIter *iter)
{
/* End reached when whole area covered */
return iter->pos >= iter->cover_end;
}
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