82 lines
2.9 KiB
C
82 lines
2.9 KiB
C
/*
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* Copyright © 2012 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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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial
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* portions of the Software.
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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
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef _WESTON_VERTEX_CLIPPING_H
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#define _WESTON_VERTEX_CLIPPING_H
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#include <stddef.h>
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#include <stdbool.h>
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#include <pixman.h>
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struct clipper_vertex {
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float x, y;
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};
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struct clipper_quad {
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struct clipper_vertex polygon[4];
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struct clipper_vertex bbox[2]; /* Valid if !axis_aligned. */
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bool axis_aligned;
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};
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/*
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* Initialize a 'quad' clipping context. 'polygon' points to an array of 4
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* vertices defining a convex quadrilateral of any winding order. Call
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* 'clipper_quad_clip()' to clip an initialized 'quad' to a clipping box.
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* Clipping is faster if 'polygon' is an axis-aligned rectangle with edges
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* parallel to the axes of the coordinate space. 'axis_aligned' indicates
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* whether 'polygon' respects the conditions above.
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*/
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void
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clipper_quad_init(struct clipper_quad *quad,
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const struct clipper_vertex polygon[4],
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bool axis_aligned);
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/*
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* Compute the boundary vertices of the intersection of a convex quadrilateral
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* stored into a 'quad' clipping context and a clipping 'box'. 'box' points to
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* an array of 2 vertices where the values of the 1st vertex are less than or
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* equal to the values of the 2nd vertex. Either 0 or [3, 8] resulting vertices,
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* with the same winding order than the 'polygon' passed to
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* 'clipper_quad_init()', are written to 'vertices'. The return value is the
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* number of vertices created.
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*/
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int
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clipper_quad_clip(struct clipper_quad *quad,
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const struct clipper_vertex box[2],
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struct clipper_vertex *restrict vertices);
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/*
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* Utility function calling 'clipper_quad_clip()' but taking a pixman_box32
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* pointer as clipping box.
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*/
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int
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clipper_quad_clip_box32(struct clipper_quad *quad,
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const struct pixman_box32 *box,
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struct clipper_vertex *restrict vertices);
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float
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clipper_float_difference(float a, float b);
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#endif
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