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The coding style has for a long time said to avoid using redundant glib
data types such as gint or gchar etc because we feel that they make the
code look unnecessarily foreign to developers coming from outside of the
Gnome developer community.
Note: When we tried to find the historical rationale for the types we
just found that they were apparently only added for consistent syntax
highlighting which didn't seem that compelling.
Up until now we have been continuing to use some of the platform
specific type such as gint{8,16,32,64} and gsize but this patch switches
us over to using the standard c99 equivalents instead so we can further
ensure that our code looks familiar to the widest range of C developers
who might potentially contribute to Cogl.
So instead of using the gint{8,16,32,64} and guint{8,16,32,64} types this
switches all Cogl code to instead use the int{8,16,32,64}_t and
uint{8,16,32,64}_t c99 types instead.
Instead of gsize we now use size_t
For now we are not going to use the c99 _Bool type and instead we have
introduced a new CoglBool type to use instead of gboolean.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 5967dad2400d32ca6319cef6cb572e81bf2c15f0)
102 lines
4.1 KiB
C
102 lines
4.1 KiB
C
/*
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* Point Inclusion in Polygon Test
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*
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* Copyright (c) 1970-2003, Wm. Randolph Franklin
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* Copyright (C) 2011 Intel Corporation.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimers.
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* 2. Redistributions in binary form must reproduce the above
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* copyright notice in the documentation and/or other materials
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* provided with the distribution.
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* 3. The name of W. Randolph Franklin may not be used to endorse or
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* promote products derived from this Software without specific
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* prior written permission.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* Note:
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* The algorithm for this point_in_poly() function was learnt from:
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* http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
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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 "cogl-util.h"
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#include "cogl-point-in-poly-private.h"
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#include <glib.h>
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/* We've made a notable change to the original algorithm referenced
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* above to make sure we have reliable results for screen aligned
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* rectangles even though there may be some numerical in-precision in
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* how the vertices of the polygon were calculated.
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*
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* We've avoided introducing an epsilon factor to the comparisons
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* since we feel there's a risk of changing some semantics in ways that
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* might not be desirable. One of those is that if you transform two
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* polygons which share an edge and test a point close to that edge
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* then this algorithm will currently give a positive result for only
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* one polygon.
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*
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* Another concern is the way this algorithm resolves the corner case
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* where the horizontal ray being cast to count edge crossings may
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* cross directly through a vertex. The solution is based on the "idea
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* of Simulation of Simplicity" and "pretends to shift the ray
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* infinitesimally down so that it either clearly intersects, or
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* clearly doesn't touch". I'm not familiar with the idea myself so I
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* expect a misplaced epsilon is likely to break that aspect of the
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* algorithm.
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*
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* The simple solution we've gone for is to pixel align the polygon
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* vertices which should eradicate most noise due to in-precision.
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*/
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int
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_cogl_util_point_in_screen_poly (float point_x,
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float point_y,
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void *vertices,
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size_t stride,
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int n_vertices)
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{
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int i, j, c = 0;
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for (i = 0, j = n_vertices - 1; i < n_vertices; j = i++)
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{
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float vert_xi = *(float *)((uint8_t *)vertices + i * stride);
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float vert_xj = *(float *)((uint8_t *)vertices + j * stride);
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float vert_yi = *(float *)((uint8_t *)vertices + i * stride +
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sizeof (float));
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float vert_yj = *(float *)((uint8_t *)vertices + j * stride +
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sizeof (float));
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vert_xi = COGL_UTIL_NEARBYINT (vert_xi);
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vert_xj = COGL_UTIL_NEARBYINT (vert_xj);
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vert_yi = COGL_UTIL_NEARBYINT (vert_yi);
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vert_yj = COGL_UTIL_NEARBYINT (vert_yj);
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if (((vert_yi > point_y) != (vert_yj > point_y)) &&
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(point_x < (vert_xj - vert_xi) * (point_y - vert_yi) /
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(vert_yj - vert_yi) + vert_xi) )
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c = !c;
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}
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return c;
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}
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