/* * Copyright © 2012 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 (including the * next paragraph) 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. */ #ifndef _WESTON_VERTEX_CLIPPING_H #define _WESTON_VERTEX_CLIPPING_H #include #include #include struct clipper_vertex { float x, y; }; struct clipper_quad { struct clipper_vertex polygon[4]; struct clipper_vertex bbox[2]; /* Valid if !axis_aligned. */ bool axis_aligned; }; /* * General purpose clipping function. Compute the boundary vertices of the * intersection of a 'polygon' and a clipping 'box'. 'polygon' points to an * array of 'polygon_len' vertices, less than or equal to 8, defining a convex * polygon of any winding order. 'box' points to an array of 2 vertices where * the values of the 1st vertex are less than or equal to the values of the 2nd * vertex. Up to 16 resulting vertices, using 'polygon' winding order, are * written to 'vertices'. The return value is the number of vertices created. */ int clipper_clip(const struct clipper_vertex *polygon, size_t polygon_len, const struct clipper_vertex box[2], struct clipper_vertex *restrict vertices); /* * Initialize a 'quad' clipping context. 'polygon' points to an array of 4 * vertices defining a convex quadrilateral of any winding order. Call * 'clipper_quad_clip()' to clip an initialized 'quad' to a clipping box. * Clipping is faster if 'polygon' is an axis-aligned rectangle with edges * parallel to the axes of the coordinate space. 'axis_aligned' indicates * whether 'polygon' respects the conditions above. */ void clipper_quad_init(struct clipper_quad *quad, const struct clipper_vertex polygon[4], bool axis_aligned); /* * Compute the boundary vertices of the intersection of a convex quadrilateral * stored into a 'quad' clipping context and a clipping 'box'. 'box' points to * an array of 2 vertices where the values of the 1st vertex are less than or * equal to the values of the 2nd vertex. Either 0 or [3, 8] resulting vertices, * with the same winding order than the 'polygon' passed to * 'clipper_quad_init()', are written to 'vertices'. The return value is the * number of vertices created. */ int clipper_quad_clip(struct clipper_quad *quad, const struct clipper_vertex box[2], struct clipper_vertex *restrict vertices); /* * Utility function calling 'clipper_quad_clip()' but taking a pixman_box32 * pointer as clipping box. */ int clipper_quad_clip_box32(struct clipper_quad *quad, const struct pixman_box32 *box, struct clipper_vertex *restrict vertices); float clipper_float_difference(float a, float b); #endif