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Diffstat (limited to 'cogl/cogl/cogl-spans.c')
| -rw-r--r-- | cogl/cogl/cogl-spans.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/cogl/cogl/cogl-spans.c b/cogl/cogl/cogl-spans.c new file mode 100644 index 000000000..e7ca67830 --- /dev/null +++ b/cogl/cogl/cogl-spans.c @@ -0,0 +1,183 @@ +/* + * Cogl + * + * A Low Level GPU Graphics and Utilities API + * + * Copyright (C) 2007,2008,2009 Intel Corporation. + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, + * modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + * + * + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "math.h" + +#include "cogl-util.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); +} + +CoglBool +_cogl_span_iter_end (CoglSpanIter *iter) +{ + /* End reached when whole area covered */ + return iter->pos >= iter->cover_end; +} + + |