1/**************************************************************************
2 *
3 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28/* Authors:  Keith Whitwell <keith@tungstengraphics.com>
29 */
30
31/* Implement line stipple by cutting lines up into smaller lines.
32 * There are hundreds of ways to implement line stipple, this is one
33 * choice that should work in all situations, requires no state
34 * manipulations, but with a penalty in terms of large amounts of
35 * generated geometry.
36 */
37
38
39#include "pipe/p_defines.h"
40#include "pipe/p_shader_tokens.h"
41#include "util/u_math.h"
42#include "util/u_memory.h"
43
44#include "draw/draw_pipe.h"
45
46
47/** Subclass of draw_stage */
48struct stipple_stage {
49   struct draw_stage stage;
50   float counter;
51   uint pattern;
52   uint factor;
53};
54
55
56static INLINE struct stipple_stage *
57stipple_stage(struct draw_stage *stage)
58{
59   return (struct stipple_stage *) stage;
60}
61
62
63/**
64 * Compute interpolated vertex attributes for 'dst' at position 't'
65 * between 'v0' and 'v1'.
66 * XXX using linear interpolation for all attribs at this time.
67 */
68static void
69screen_interp( struct draw_context *draw,
70               struct vertex_header *dst,
71               float t,
72               const struct vertex_header *v0,
73               const struct vertex_header *v1 )
74{
75   uint attr;
76   int num_outputs = draw_current_shader_outputs(draw);
77   for (attr = 0; attr < num_outputs; attr++) {
78      const float *val0 = v0->data[attr];
79      const float *val1 = v1->data[attr];
80      float *newv = dst->data[attr];
81      uint i;
82      for (i = 0; i < 4; i++) {
83         newv[i] = val0[i] + t * (val1[i] - val0[i]);
84      }
85   }
86}
87
88
89static void
90emit_segment(struct draw_stage *stage, struct prim_header *header,
91             float t0, float t1)
92{
93   struct vertex_header *v0new = dup_vert(stage, header->v[0], 0);
94   struct vertex_header *v1new = dup_vert(stage, header->v[1], 1);
95   struct prim_header newprim = *header;
96
97   if (t0 > 0.0) {
98      screen_interp( stage->draw, v0new, t0, header->v[0], header->v[1] );
99      newprim.v[0] = v0new;
100   }
101
102   if (t1 < 1.0) {
103      screen_interp( stage->draw, v1new, t1, header->v[0], header->v[1] );
104      newprim.v[1] = v1new;
105   }
106
107   stage->next->line( stage->next, &newprim );
108}
109
110
111static INLINE unsigned
112stipple_test(int counter, ushort pattern, int factor)
113{
114   int b = (counter / factor) & 0xf;
115   return (1 << b) & pattern;
116}
117
118
119static void
120stipple_line(struct draw_stage *stage, struct prim_header *header)
121{
122   struct stipple_stage *stipple = stipple_stage(stage);
123   struct vertex_header *v0 = header->v[0];
124   struct vertex_header *v1 = header->v[1];
125   const unsigned pos = draw_current_shader_position_output(stage->draw);
126   const float *pos0 = v0->data[pos];
127   const float *pos1 = v1->data[pos];
128   float start = 0;
129   int state = 0;
130
131   float x0 = pos0[0];
132   float x1 = pos1[0];
133   float y0 = pos0[1];
134   float y1 = pos1[1];
135
136   float dx = x0 > x1 ? x0 - x1 : x1 - x0;
137   float dy = y0 > y1 ? y0 - y1 : y1 - y0;
138
139   float length = MAX2(dx, dy);
140   int i;
141
142   if (header->flags & DRAW_PIPE_RESET_STIPPLE)
143      stipple->counter = 0;
144
145
146   /* XXX ToDo: intead of iterating pixel-by-pixel, use a look-up table.
147    */
148   for (i = 0; i < length; i++) {
149      int result = stipple_test( (int) stipple->counter+i,
150                                 (ushort) stipple->pattern, stipple->factor );
151      if (result != state) {
152         /* changing from "off" to "on" or vice versa */
153	 if (state) {
154	    if (start != i) {
155               /* finishing an "on" segment */
156	       emit_segment( stage, header, start / length, i / length );
157            }
158	 }
159	 else {
160            /* starting an "on" segment */
161	    start = (float) i;
162	 }
163	 state = result;
164      }
165   }
166
167   if (state && start < length)
168      emit_segment( stage, header, start / length, 1.0 );
169
170   stipple->counter += length;
171}
172
173
174static void
175reset_stipple_counter(struct draw_stage *stage)
176{
177   struct stipple_stage *stipple = stipple_stage(stage);
178   stipple->counter = 0;
179   stage->next->reset_stipple_counter( stage->next );
180}
181
182static void
183stipple_reset_point(struct draw_stage *stage, struct prim_header *header)
184{
185   struct stipple_stage *stipple = stipple_stage(stage);
186   stipple->counter = 0;
187   stage->next->point(stage->next, header);
188}
189
190static void
191stipple_reset_tri(struct draw_stage *stage, struct prim_header *header)
192{
193   struct stipple_stage *stipple = stipple_stage(stage);
194   stipple->counter = 0;
195   stage->next->tri(stage->next, header);
196}
197
198
199static void
200stipple_first_line(struct draw_stage *stage,
201		   struct prim_header *header)
202{
203   struct stipple_stage *stipple = stipple_stage(stage);
204   struct draw_context *draw = stage->draw;
205
206   stipple->pattern = draw->rasterizer->line_stipple_pattern;
207   stipple->factor = draw->rasterizer->line_stipple_factor + 1;
208
209   stage->line = stipple_line;
210   stage->line( stage, header );
211}
212
213
214static void
215stipple_flush(struct draw_stage *stage, unsigned flags)
216{
217   stage->line = stipple_first_line;
218   stage->next->flush( stage->next, flags );
219}
220
221
222
223
224static void
225stipple_destroy( struct draw_stage *stage )
226{
227   draw_free_temp_verts( stage );
228   FREE( stage );
229}
230
231
232/**
233 * Create line stippler stage
234 */
235struct draw_stage *draw_stipple_stage( struct draw_context *draw )
236{
237   struct stipple_stage *stipple = CALLOC_STRUCT(stipple_stage);
238   if (stipple == NULL)
239      goto fail;
240
241   stipple->stage.draw = draw;
242   stipple->stage.name = "stipple";
243   stipple->stage.next = NULL;
244   stipple->stage.point = stipple_reset_point;
245   stipple->stage.line = stipple_first_line;
246   stipple->stage.tri = stipple_reset_tri;
247   stipple->stage.reset_stipple_counter = reset_stipple_counter;
248   stipple->stage.flush = stipple_flush;
249   stipple->stage.destroy = stipple_destroy;
250
251   if (!draw_alloc_temp_verts( &stipple->stage, 2 ))
252      goto fail;
253
254   return &stipple->stage;
255
256fail:
257   if (stipple)
258      stipple->stage.destroy( &stipple->stage );
259
260   return NULL;
261}
262