fbtrap.c revision 6747b715 
1/*
2 * Copyright © 2004 Keith Packard
3 *
4 * Permission to use, copy, modify, distribute, and sell this software and its
5 * documentation for any purpose is hereby granted without fee, provided that
6 * the above copyright notice appear in all copies and that both that
7 * copyright notice and this permission notice appear in supporting
8 * documentation, and that the name of Keith Packard not be used in
9 * advertising or publicity pertaining to distribution of the software without
10 * specific, written prior permission.  Keith Packard makes no
11 * representations about the suitability of this software for any purpose.  It
12 * is provided "as is" without express or implied warranty.
13 *
14 * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
15 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
16 * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
17 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
18 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
19 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
20 * PERFORMANCE OF THIS SOFTWARE.
21 */
22
23#ifdef HAVE_DIX_CONFIG_H
24#include <dix-config.h>
25#endif
26
27#include "fb.h"
28
29#include "picturestr.h"
30#include "mipict.h"
31#include "renderedge.h"
32#include "fbpict.h"
33
34void
35fbAddTraps (PicturePtr	pPicture,
36	    INT16	x_off,
37	    INT16	y_off,
38	    int		ntrap,
39	    xTrap	*traps)
40{
41    int image_xoff, image_yoff;
42    pixman_image_t *image = image_from_pict (pPicture, FALSE, &image_xoff, &image_yoff);
43
44    if (!image)
45	return;
46
47    pixman_add_traps (image, x_off, y_off, ntrap, (pixman_trap_t *)traps);
48
49    free_pixman_pict (pPicture, image);
50}
51
52void
53fbRasterizeTrapezoid (PicturePtr    pPicture,
54		      xTrapezoid  *trap,
55		      int	    x_off,
56		      int	    y_off)
57{
58    int	mask_xoff, mask_yoff;
59    pixman_image_t *image = image_from_pict (pPicture, FALSE, &mask_xoff, &mask_yoff);
60
61    if (!image)
62	return;
63
64    pixman_rasterize_trapezoid (image, (pixman_trapezoid_t *)trap, x_off, y_off);
65
66    free_pixman_pict (pPicture, image);
67}
68
69static int
70_GreaterY (xPointFixed *a, xPointFixed *b)
71{
72    if (a->y == b->y)
73	return a->x > b->x;
74    return a->y > b->y;
75}
76
77/*
78 * Note that the definition of this function is a bit odd because
79 * of the X coordinate space (y increasing downwards).
80 */
81static int
82_Clockwise (xPointFixed *ref, xPointFixed *a, xPointFixed *b)
83{
84    xPointFixed	ad, bd;
85
86    ad.x = a->x - ref->x;
87    ad.y = a->y - ref->y;
88    bd.x = b->x - ref->x;
89    bd.y = b->y - ref->y;
90
91    return ((xFixed_32_32) bd.y * ad.x - (xFixed_32_32) ad.y * bd.x) < 0;
92}
93
94/* FIXME -- this could be made more efficient */
95void
96fbAddTriangles (PicturePtr  pPicture,
97		INT16	    x_off,
98		INT16	    y_off,
99		int	    ntri,
100		xTriangle *tris)
101{
102    xPointFixed	  *top, *left, *right, *tmp;
103    xTrapezoid	    trap;
104
105    for (; ntri; ntri--, tris++)
106    {
107	top = &tris->p1;
108	left = &tris->p2;
109	right = &tris->p3;
110	if (_GreaterY (top, left)) {
111	    tmp = left; left = top; top = tmp;
112	}
113	if (_GreaterY (top, right)) {
114	    tmp = right; right = top; top = tmp;
115	}
116	if (_Clockwise (top, right, left)) {
117	    tmp = right; right = left; left = tmp;
118	}
119
120	/*
121	 * Two cases:
122	 *
123	 *		+		+
124	 *	       / \             / \
125	 *	      /   \           /   \
126	 *	     /     +         +     \
127	 *      /    --           --    \
128	 *     /   --               --   \
129	 *    / ---                   --- \
130	 *	 +--                         --+
131	 */
132
133	trap.top = top->y;
134	trap.left.p1 = *top;
135	trap.left.p2 = *left;
136	trap.right.p1 = *top;
137	trap.right.p2 = *right;
138	if (right->y < left->y)
139	    trap.bottom = right->y;
140	else
141	    trap.bottom = left->y;
142	fbRasterizeTrapezoid (pPicture, &trap, x_off, y_off);
143	if (right->y < left->y)
144	{
145	    trap.top = right->y;
146	    trap.bottom = left->y;
147	    trap.right.p1 = *right;
148	    trap.right.p2 = *left;
149	}
150	else
151	{
152	    trap.top = left->y;
153	    trap.bottom = right->y;
154	    trap.left.p1 = *left;
155	    trap.left.p2 = *right;
156	}
157	fbRasterizeTrapezoid (pPicture, &trap, x_off, y_off);
158    }
159}
160
161