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5387aa0e9e
When we implement atlas textures we will probably want to use the spans API to handle texture repeating so it doesn't make sense to leave the code in cogl-texture-2d-sliced.c. Since it's a standalone set of data structures and algorithms it also seems reasonable to split out from cogl-texture.
133 lines
3.6 KiB
C
133 lines
3.6 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2007,2008,2009 Intel Corporation.
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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, 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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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "math.h"
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#include "cogl.h"
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#include "cogl-internal.h"
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#include "cogl-spans.h"
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void
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_cogl_span_iter_update (CoglSpanIter *iter)
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{
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/* Pick current span */
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iter->span = &g_array_index (iter->array, CoglSpan, iter->index);
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/* Offset next position by span size */
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iter->next_pos = iter->pos +
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(float)(iter->span->size - iter->span->waste);
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/* Check if span intersects the area to cover */
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if (iter->next_pos <= iter->cover_start ||
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iter->pos >= iter->cover_end)
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{
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/* Intersection undefined */
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iter->intersects = FALSE;
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return;
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}
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iter->intersects = TRUE;
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/* Clip start position to coverage area */
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if (iter->pos < iter->cover_start)
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iter->intersect_start = iter->cover_start;
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else
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iter->intersect_start = iter->pos;
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/* Clip end position to coverage area */
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if (iter->next_pos > iter->cover_end)
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iter->intersect_end = iter->cover_end;
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else
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iter->intersect_end = iter->next_pos;
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}
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void
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_cogl_span_iter_begin (CoglSpanIter *iter,
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GArray *spans,
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float normalize_factor,
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float cover_start,
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float cover_end)
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{
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float cover_start_normalized;
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iter->index = 0;
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iter->span = NULL;
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iter->array = spans;
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/* We always iterate in a positive direction from the origin. If
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* iter->flipped == TRUE that means whoever is using this API should
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* interpreted the current span as extending in the opposite direction. I.e.
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* it extends to the left if iterating the X axis, or up if the Y axis. */
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if (cover_start > cover_end)
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{
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float tmp = cover_start;
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cover_start = cover_end;
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cover_end = tmp;
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iter->flipped = TRUE;
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}
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else
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iter->flipped = FALSE;
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/* The texture spans cover the normalized texture coordinate space ranging
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* from [0,1] but to help support repeating of sliced textures we allow
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* iteration of any range so we need to relate the start of the range to the
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* nearest point equivalent to 0.
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*/
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cover_start_normalized = cover_start / normalize_factor;
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iter->origin = floorf (cover_start_normalized) * normalize_factor;
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iter->cover_start = cover_start;
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iter->cover_end = cover_end;
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iter->pos = iter->origin;
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/* Update intersection */
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_cogl_span_iter_update (iter);
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}
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void
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_cogl_span_iter_next (CoglSpanIter *iter)
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{
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/* Move current position */
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iter->pos = iter->next_pos;
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/* Pick next slice (wrap when last reached) */
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iter->index = (iter->index + 1) % iter->array->len;
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/* Update intersection */
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_cogl_span_iter_update (iter);
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}
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gboolean
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_cogl_span_iter_end (CoglSpanIter *iter)
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{
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/* End reached when whole area covered */
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return iter->pos >= iter->cover_end;
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}
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