1/**************************************************************************
2 *
3 * Copyright 2007 VMware, Inc.
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 VMWARE 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 <keithw@vmware.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   unsigned counter;
51   ushort pattern;
52   ushort factor;
53   bool rectangular;
54};
55
56
57static inline struct stipple_stage *
58stipple_stage(struct draw_stage *stage)
59{
60   return (struct stipple_stage *) stage;
61}
62
63
64/**
65 * Compute interpolated vertex attributes for 'dst' at position 't'
66 * between 'v0' and 'v1'.
67 * XXX using linear interpolation for all attribs at this time.
68 */
69static void
70screen_interp(struct draw_context *draw,
71              struct vertex_header *dst,
72              float t,
73              const struct vertex_header *v0,
74              const struct vertex_header *v1)
75{
76   uint attr;
77   uint num_outputs = draw_current_shader_outputs(draw);
78   for (attr = 0; attr < num_outputs; attr++) {
79      const float *val0 = v0->data[attr];
80      const float *val1 = v1->data[attr];
81      float *newv = dst->data[attr];
82      uint i;
83      for (i = 0; i < 4; i++) {
84         newv[i] = val0[i] + t * (val1[i] - val0[i]);
85      }
86   }
87}
88
89
90static void
91emit_segment(struct draw_stage *stage, struct prim_header *header,
92             float t0, float t1)
93{
94   struct vertex_header *v0new = dup_vert(stage, header->v[0], 0);
95   struct vertex_header *v1new = dup_vert(stage, header->v[1], 1);
96   struct prim_header newprim = *header;
97
98   if (t0 > 0.0) {
99      screen_interp(stage->draw, v0new, t0, header->v[0], header->v[1]);
100      newprim.v[0] = v0new;
101   }
102
103   if (t1 < 1.0) {
104      screen_interp(stage->draw, v1new, t1, header->v[0], header->v[1]);
105      newprim.v[1] = v1new;
106   }
107
108   stage->next->line(stage->next, &newprim);
109}
110
111
112static inline bool
113stipple_test(unsigned counter, ushort pattern, ushort factor)
114{
115   unsigned b = (counter / factor) & 0xf;
116   return !!((1 << b) & pattern);
117}
118
119
120static void
121stipple_line(struct draw_stage *stage, struct prim_header *header)
122{
123   struct stipple_stage *stipple = stipple_stage(stage);
124   struct vertex_header *v0 = header->v[0];
125   struct vertex_header *v1 = header->v[1];
126   const unsigned pos = draw_current_shader_position_output(stage->draw);
127   const float *pos0 = v0->data[pos];
128   const float *pos1 = v1->data[pos];
129   float start = 0;
130   bool state = 0;
131
132   float x0 = pos0[0];
133   float x1 = pos1[0];
134   float y0 = pos0[1];
135   float y1 = pos1[1];
136
137   float length;
138   int i;
139   int intlength;
140
141   if (header->flags & DRAW_PIPE_RESET_STIPPLE)
142      stipple->counter = 0;
143
144   if (stipple->rectangular) {
145      float dx = x1 - x0;
146      float dy = y1 - y0;
147      length = sqrtf(dx*dx + dy*dy);
148   } else {
149      float dx = x0 > x1 ? x0 - x1 : x1 - x0;
150      float dy = y0 > y1 ? y0 - y1 : y1 - y0;
151      length = MAX2(dx, dy);
152   }
153
154   if (util_is_inf_or_nan(length))
155      intlength = 0;
156   else
157      intlength = ceilf(length);
158
159   /* XXX ToDo: instead of iterating pixel-by-pixel, use a look-up table.
160    */
161   for (i = 0; i < intlength; i++) {
162      bool result = stipple_test(stipple->counter + i,
163                                 stipple->pattern, stipple->factor);
164      if (result != state) {
165         /* changing from "off" to "on" or vice versa */
166         if (state) {
167            /* finishing an "on" segment */
168            emit_segment(stage, header, start / length, i / length);
169         }
170         else {
171            /* starting an "on" segment */
172            start = (float)i;
173         }
174         state = result;
175      }
176   }
177
178   if (state && start < length)
179      emit_segment(stage, header, start / length, 1.0);
180
181   stipple->counter += intlength;
182}
183
184
185static void
186reset_stipple_counter(struct draw_stage *stage)
187{
188   struct stipple_stage *stipple = stipple_stage(stage);
189   stipple->counter = 0;
190   stage->next->reset_stipple_counter(stage->next);
191}
192
193static void
194stipple_reset_point(struct draw_stage *stage, struct prim_header *header)
195{
196   struct stipple_stage *stipple = stipple_stage(stage);
197   stipple->counter = 0;
198   stage->next->point(stage->next, header);
199}
200
201static void
202stipple_reset_tri(struct draw_stage *stage, struct prim_header *header)
203{
204   struct stipple_stage *stipple = stipple_stage(stage);
205   stipple->counter = 0;
206   stage->next->tri(stage->next, header);
207}
208
209
210static void
211stipple_first_line(struct draw_stage *stage,
212                   struct prim_header *header)
213{
214   struct stipple_stage *stipple = stipple_stage(stage);
215   struct draw_context *draw = stage->draw;
216
217   stipple->pattern = draw->rasterizer->line_stipple_pattern;
218   stipple->factor = draw->rasterizer->line_stipple_factor + 1;
219   stipple->rectangular = draw->rasterizer->line_rectangular;
220
221   stage->line = stipple_line;
222   stage->line(stage, header);
223}
224
225
226static void
227stipple_flush(struct draw_stage *stage, unsigned flags)
228{
229   stage->line = stipple_first_line;
230   stage->next->flush(stage->next, flags);
231}
232
233
234static void
235stipple_destroy(struct draw_stage *stage)
236{
237   draw_free_temp_verts(stage);
238   FREE(stage);
239}
240
241
242/**
243 * Create line stippler stage
244 */
245struct draw_stage *
246draw_stipple_stage(struct draw_context *draw)
247{
248   struct stipple_stage *stipple = CALLOC_STRUCT(stipple_stage);
249   if (!stipple)
250      goto fail;
251
252   stipple->stage.draw = draw;
253   stipple->stage.name = "stipple";
254   stipple->stage.next = NULL;
255   stipple->stage.point = stipple_reset_point;
256   stipple->stage.line = stipple_first_line;
257   stipple->stage.tri = stipple_reset_tri;
258   stipple->stage.reset_stipple_counter = reset_stipple_counter;
259   stipple->stage.flush = stipple_flush;
260   stipple->stage.destroy = stipple_destroy;
261
262   if (!draw_alloc_temp_verts(&stipple->stage, 2))
263      goto fail;
264
265   return &stipple->stage;
266
267fail:
268   if (stipple)
269      stipple->stage.destroy(&stipple->stage);
270
271   return NULL;
272}
273