• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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 #include "pipe/p_context.h"
32 #include "pipe/p_defines.h"
33 #include "pipe/p_shader_tokens.h"
34 #include "util/u_math.h"
35 #include "util/u_memory.h"
36 #include "draw_private.h"
37 #include "draw_pipe.h"
38 
39 
40 struct wideline_stage {
41    struct draw_stage stage;
42 
43    float half_line_width;
44 };
45 
46 
47 
wideline_stage(struct draw_stage * stage)48 static INLINE struct wideline_stage *wideline_stage( struct draw_stage *stage )
49 {
50    return (struct wideline_stage *)stage;
51 }
52 
53 
54 
55 /**
56  * Draw a wide line by drawing a quad (two triangles).
57  */
wideline_line(struct draw_stage * stage,struct prim_header * header)58 static void wideline_line( struct draw_stage *stage,
59                            struct prim_header *header )
60 {
61    /*const struct wideline_stage *wide = wideline_stage(stage);*/
62    const unsigned pos = draw_current_shader_position_output(stage->draw);
63    const float half_width = 0.5f * stage->draw->rasterizer->line_width;
64 
65    struct prim_header tri;
66 
67    struct vertex_header *v0 = dup_vert(stage, header->v[0], 0);
68    struct vertex_header *v1 = dup_vert(stage, header->v[0], 1);
69    struct vertex_header *v2 = dup_vert(stage, header->v[1], 2);
70    struct vertex_header *v3 = dup_vert(stage, header->v[1], 3);
71 
72    float *pos0 = v0->data[pos];
73    float *pos1 = v1->data[pos];
74    float *pos2 = v2->data[pos];
75    float *pos3 = v3->data[pos];
76 
77    const float dx = fabsf(pos0[0] - pos2[0]);
78    const float dy = fabsf(pos0[1] - pos2[1]);
79 
80    const boolean gl_rasterization_rules =
81       stage->draw->rasterizer->gl_rasterization_rules;
82 
83    /* small tweak to meet GL specification */
84    const float bias = gl_rasterization_rules ? 0.125f : 0.0f;
85 
86    /*
87     * Draw wide line as a quad (two tris) by "stretching" the line along
88     * X or Y.
89     * We need to tweak coords in several ways to be conformant here.
90     */
91 
92    if (dx > dy) {
93       /* x-major line */
94       pos0[1] = pos0[1] - half_width - bias;
95       pos1[1] = pos1[1] + half_width - bias;
96       pos2[1] = pos2[1] - half_width - bias;
97       pos3[1] = pos3[1] + half_width - bias;
98       if (gl_rasterization_rules) {
99          if (pos0[0] < pos2[0]) {
100             /* left to right line */
101             pos0[0] -= 0.5f;
102             pos1[0] -= 0.5f;
103             pos2[0] -= 0.5f;
104             pos3[0] -= 0.5f;
105          }
106          else {
107             /* right to left line */
108             pos0[0] += 0.5f;
109             pos1[0] += 0.5f;
110             pos2[0] += 0.5f;
111             pos3[0] += 0.5f;
112          }
113       }
114    }
115    else {
116       /* y-major line */
117       pos0[0] = pos0[0] - half_width + bias;
118       pos1[0] = pos1[0] + half_width + bias;
119       pos2[0] = pos2[0] - half_width + bias;
120       pos3[0] = pos3[0] + half_width + bias;
121       if (gl_rasterization_rules) {
122          if (pos0[1] < pos2[1]) {
123             /* top to bottom line */
124             pos0[1] -= 0.5f;
125             pos1[1] -= 0.5f;
126             pos2[1] -= 0.5f;
127             pos3[1] -= 0.5f;
128          }
129          else {
130             /* bottom to top line */
131             pos0[1] += 0.5f;
132             pos1[1] += 0.5f;
133             pos2[1] += 0.5f;
134             pos3[1] += 0.5f;
135          }
136       }
137    }
138 
139    tri.det = header->det;  /* only the sign matters */
140    tri.v[0] = v0;
141    tri.v[1] = v2;
142    tri.v[2] = v3;
143    stage->next->tri( stage->next, &tri );
144 
145    tri.v[0] = v0;
146    tri.v[1] = v3;
147    tri.v[2] = v1;
148    stage->next->tri( stage->next, &tri );
149 }
150 
151 
wideline_first_line(struct draw_stage * stage,struct prim_header * header)152 static void wideline_first_line( struct draw_stage *stage,
153                                  struct prim_header *header )
154 {
155    struct draw_context *draw = stage->draw;
156    struct pipe_context *pipe = draw->pipe;
157    const struct pipe_rasterizer_state *rast = draw->rasterizer;
158    void *r;
159 
160    /* Disable triangle culling, stippling, unfilled mode etc. */
161    r = draw_get_rasterizer_no_cull(draw, rast->scissor, rast->flatshade);
162    draw->suspend_flushing = TRUE;
163    pipe->bind_rasterizer_state(pipe, r);
164    draw->suspend_flushing = FALSE;
165 
166    stage->line = wideline_line;
167 
168    wideline_line(stage, header);
169 }
170 
171 
wideline_flush(struct draw_stage * stage,unsigned flags)172 static void wideline_flush( struct draw_stage *stage, unsigned flags )
173 {
174    struct draw_context *draw = stage->draw;
175    struct pipe_context *pipe = draw->pipe;
176 
177    stage->line = wideline_first_line;
178    stage->next->flush( stage->next, flags );
179 
180    /* restore original rasterizer state */
181    if (draw->rast_handle) {
182       draw->suspend_flushing = TRUE;
183       pipe->bind_rasterizer_state(pipe, draw->rast_handle);
184       draw->suspend_flushing = FALSE;
185    }
186 }
187 
188 
wideline_reset_stipple_counter(struct draw_stage * stage)189 static void wideline_reset_stipple_counter( struct draw_stage *stage )
190 {
191    stage->next->reset_stipple_counter( stage->next );
192 }
193 
194 
wideline_destroy(struct draw_stage * stage)195 static void wideline_destroy( struct draw_stage *stage )
196 {
197    draw_free_temp_verts( stage );
198    FREE( stage );
199 }
200 
201 
draw_wide_line_stage(struct draw_context * draw)202 struct draw_stage *draw_wide_line_stage( struct draw_context *draw )
203 {
204    struct wideline_stage *wide = CALLOC_STRUCT(wideline_stage);
205    if (wide == NULL)
206       goto fail;
207 
208    wide->stage.draw = draw;
209    wide->stage.name = "wide-line";
210    wide->stage.next = NULL;
211    wide->stage.point = draw_pipe_passthrough_point;
212    wide->stage.line = wideline_first_line;
213    wide->stage.tri = draw_pipe_passthrough_tri;
214    wide->stage.flush = wideline_flush;
215    wide->stage.reset_stipple_counter = wideline_reset_stipple_counter;
216    wide->stage.destroy = wideline_destroy;
217 
218    if (!draw_alloc_temp_verts( &wide->stage, 4 ))
219       goto fail;
220 
221    return &wide->stage;
222 
223 fail:
224    if (wide)
225       wide->stage.destroy( &wide->stage );
226 
227    return NULL;
228 }
229