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f5dac3a5d9
Group all the three config files from clutter/cogl/meta into one and also remove unnused configurations and replace duplicated ones This also fixes Cogl usage of HAS_X11/HAS_XLIB to match the expected build options Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3368>
100 lines
4.1 KiB
C
100 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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#include "config.h"
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#include "cogl/cogl-util.h"
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#include "cogl/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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