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27 
28 /* Authors:  Keith Whitwell <keithw@vmware.com>
29  */
30 
31 /**
32  * Notes on wide points and sprite mode:
33  *
34  * In wide point/sprite mode we effectively need to convert each incoming
35  * vertex into four outgoing vertices specifying the corners of a quad.
36  * Since we don't (yet) have geometry shaders, we have to handle this here
37  * in the draw module.
38  *
39  * For sprites, it also means that this is where we have to handle texcoords
40  * for the vertices of the quad.  OpenGL's GL_COORD_REPLACE state specifies
41  * if/how enabled texcoords are automatically generated for sprites.  We pass
42  * that info through gallium in the pipe_rasterizer_state::sprite_coord_mode
43  * array.
44  *
45  * Additionally, GLSL's gl_PointCoord fragment attribute has to be handled
46  * here as well.  This is basically an additional texture/generic attribute
47  * that varies .x from 0 to 1 horizontally across the point and varies .y
48  * vertically from 0 to 1 down the sprite.
49  *
50  * With geometry shaders, the gallium frontends could create a GS to do
51  * most/all of this.
52  */
53 
54 
55 #include "pipe/p_screen.h"
56 #include "pipe/p_context.h"
57 #include "util/u_math.h"
58 #include "util/u_memory.h"
59 #include "pipe/p_defines.h"
60 #include "pipe/p_shader_tokens.h"
61 #include "draw_fs.h"
62 #include "draw_vs.h"
63 #include "draw_pipe.h"
64 
65 
66 struct widepoint_stage {
67    struct draw_stage stage;  /**< base class */
68 
69    float half_point_size;
70 
71    float xbias;
72    float ybias;
73 
74    /** for automatic texcoord generation/replacement */
75    uint num_texcoord_gen;
76    uint texcoord_gen_slot[PIPE_MAX_SHADER_OUTPUTS];
77 
78    /* TGSI_SEMANTIC to which sprite_coord_enable applies */
79    enum tgsi_semantic sprite_coord_semantic;
80 
81    int psize_slot;
82 };
83 
84 
85 
86 static inline struct widepoint_stage *
widepoint_stage(struct draw_stage * stage)87 widepoint_stage( struct draw_stage *stage )
88 {
89    return (struct widepoint_stage *)stage;
90 }
91 
92 
93 /**
94  * Set the vertex texcoords for sprite mode.
95  * Coords may be left untouched or set to a right-side-up or upside-down
96  * orientation.
97  */
set_texcoords(const struct widepoint_stage * wide,struct vertex_header * v,const float tc[4])98 static void set_texcoords(const struct widepoint_stage *wide,
99                           struct vertex_header *v, const float tc[4])
100 {
101    const struct draw_context *draw = wide->stage.draw;
102    const struct pipe_rasterizer_state *rast = draw->rasterizer;
103    const uint texcoord_mode = rast->sprite_coord_mode;
104    uint i;
105 
106    for (i = 0; i < wide->num_texcoord_gen; i++) {
107       const uint slot = wide->texcoord_gen_slot[i];
108       v->data[slot][0] = tc[0];
109       if (texcoord_mode == PIPE_SPRITE_COORD_LOWER_LEFT)
110          v->data[slot][1] = 1.0f - tc[1];
111       else
112          v->data[slot][1] = tc[1];
113       v->data[slot][2] = tc[2];
114       v->data[slot][3] = tc[3];
115    }
116 }
117 
118 
119 /* If there are lots of sprite points (and why wouldn't there be?) it
120  * would probably be more sensible to change hardware setup to
121  * optimize this rather than doing the whole thing in software like
122  * this.
123  */
widepoint_point(struct draw_stage * stage,struct prim_header * header)124 static void widepoint_point( struct draw_stage *stage,
125                              struct prim_header *header )
126 {
127    const struct widepoint_stage *wide = widepoint_stage(stage);
128    const unsigned pos = draw_current_shader_position_output(stage->draw);
129    const boolean sprite = (boolean) stage->draw->rasterizer->point_quad_rasterization;
130    float half_size;
131    float left_adj, right_adj, bot_adj, top_adj;
132 
133    struct prim_header tri;
134 
135    /* four dups of original vertex */
136    struct vertex_header *v0 = dup_vert(stage, header->v[0], 0);
137    struct vertex_header *v1 = dup_vert(stage, header->v[0], 1);
138    struct vertex_header *v2 = dup_vert(stage, header->v[0], 2);
139    struct vertex_header *v3 = dup_vert(stage, header->v[0], 3);
140 
141    float *pos0 = v0->data[pos];
142    float *pos1 = v1->data[pos];
143    float *pos2 = v2->data[pos];
144    float *pos3 = v3->data[pos];
145 
146    /* point size is either per-vertex or fixed size */
147    if (wide->psize_slot >= 0) {
148       half_size = header->v[0]->data[wide->psize_slot][0];
149       half_size *= 0.5f;
150    }
151    else {
152       half_size = wide->half_point_size;
153    }
154 
155    left_adj = -half_size + wide->xbias;
156    right_adj = half_size + wide->xbias;
157    bot_adj = half_size + wide->ybias;
158    top_adj = -half_size + wide->ybias;
159 
160    pos0[0] += left_adj;
161    pos0[1] += top_adj;
162 
163    pos1[0] += left_adj;
164    pos1[1] += bot_adj;
165 
166    pos2[0] += right_adj;
167    pos2[1] += top_adj;
168 
169    pos3[0] += right_adj;
170    pos3[1] += bot_adj;
171 
172    if (sprite) {
173       static const float tex00[4] = { 0, 0, 0, 1 };
174       static const float tex01[4] = { 0, 1, 0, 1 };
175       static const float tex11[4] = { 1, 1, 0, 1 };
176       static const float tex10[4] = { 1, 0, 0, 1 };
177       set_texcoords( wide, v0, tex00 );
178       set_texcoords( wide, v1, tex01 );
179       set_texcoords( wide, v2, tex10 );
180       set_texcoords( wide, v3, tex11 );
181    }
182 
183    tri.det = header->det;  /* only the sign matters */
184    tri.v[0] = v0;
185    tri.v[1] = v2;
186    tri.v[2] = v3;
187    stage->next->tri( stage->next, &tri );
188 
189    tri.v[0] = v0;
190    tri.v[1] = v3;
191    tri.v[2] = v1;
192    stage->next->tri( stage->next, &tri );
193 }
194 
195 
196 static void
widepoint_first_point(struct draw_stage * stage,struct prim_header * header)197 widepoint_first_point(struct draw_stage *stage,
198                       struct prim_header *header)
199 {
200    struct widepoint_stage *wide = widepoint_stage(stage);
201    struct draw_context *draw = stage->draw;
202    struct pipe_context *pipe = draw->pipe;
203    const struct pipe_rasterizer_state *rast = draw->rasterizer;
204    void *r;
205 
206    wide->half_point_size = 0.5f * rast->point_size;
207    wide->xbias = 0.0;
208    wide->ybias = 0.0;
209 
210    if (rast->half_pixel_center) {
211       wide->xbias = 0.125;
212       wide->ybias = -0.125;
213    }
214 
215    /* Disable triangle culling, stippling, unfilled mode etc. */
216    r = draw_get_rasterizer_no_cull(draw, rast);
217    draw->suspend_flushing = TRUE;
218    pipe->bind_rasterizer_state(pipe, r);
219    draw->suspend_flushing = FALSE;
220 
221    /* XXX we won't know the real size if it's computed by the vertex shader! */
222    if ((rast->point_size > draw->pipeline.wide_point_threshold) ||
223        (rast->point_quad_rasterization && draw->pipeline.point_sprite)) {
224       stage->point = widepoint_point;
225    }
226    else {
227       stage->point = draw_pipe_passthrough_point;
228    }
229 
230    draw_remove_extra_vertex_attribs(draw);
231 
232    if (rast->point_quad_rasterization) {
233       const struct draw_fragment_shader *fs = draw->fs.fragment_shader;
234       uint i;
235 
236       assert(fs);
237 
238       wide->num_texcoord_gen = 0;
239 
240       /* Loop over fragment shader inputs looking for the PCOORD input or inputs
241        * for which bit 'k' in sprite_coord_enable is set.
242        */
243       for (i = 0; i < fs->info.num_inputs; i++) {
244          int slot;
245          const enum tgsi_semantic sn = fs->info.input_semantic_name[i];
246          const unsigned si = fs->info.input_semantic_index[i];
247 
248          if (sn == wide->sprite_coord_semantic) {
249             /* Note that sprite_coord_enable is a bitfield of 32 bits. */
250             if (si >= 32 || !(rast->sprite_coord_enable & (1 << si)))
251                continue;
252          } else if (sn != TGSI_SEMANTIC_PCOORD) {
253             continue;
254          }
255 
256          /* OK, this generic attribute needs to be replaced with a
257           * sprite coord (see above).
258           */
259          slot = draw_alloc_extra_vertex_attrib(draw, sn, si);
260 
261          /* add this slot to the texcoord-gen list */
262          wide->texcoord_gen_slot[wide->num_texcoord_gen++] = slot;
263       }
264    }
265 
266    wide->psize_slot = -1;
267    if (rast->point_size_per_vertex) {
268       /* find PSIZ vertex output */
269       wide->psize_slot = draw_find_shader_output(draw, TGSI_SEMANTIC_PSIZE, 0);
270    }
271 
272    stage->point( stage, header );
273 }
274 
275 
widepoint_flush(struct draw_stage * stage,unsigned flags)276 static void widepoint_flush( struct draw_stage *stage, unsigned flags )
277 {
278    struct draw_context *draw = stage->draw;
279    struct pipe_context *pipe = draw->pipe;
280 
281    stage->point = widepoint_first_point;
282    stage->next->flush( stage->next, flags );
283 
284    draw_remove_extra_vertex_attribs(draw);
285 
286    /* restore original rasterizer state */
287    if (draw->rast_handle) {
288       draw->suspend_flushing = TRUE;
289       pipe->bind_rasterizer_state(pipe, draw->rast_handle);
290       draw->suspend_flushing = FALSE;
291    }
292 }
293 
294 
widepoint_reset_stipple_counter(struct draw_stage * stage)295 static void widepoint_reset_stipple_counter( struct draw_stage *stage )
296 {
297    stage->next->reset_stipple_counter( stage->next );
298 }
299 
300 
widepoint_destroy(struct draw_stage * stage)301 static void widepoint_destroy( struct draw_stage *stage )
302 {
303    draw_free_temp_verts( stage );
304    FREE( stage );
305 }
306 
307 
draw_wide_point_stage(struct draw_context * draw)308 struct draw_stage *draw_wide_point_stage( struct draw_context *draw )
309 {
310    struct widepoint_stage *wide = CALLOC_STRUCT(widepoint_stage);
311    if (!wide)
312       goto fail;
313 
314    wide->stage.draw = draw;
315    wide->stage.name = "wide-point";
316    wide->stage.next = NULL;
317    wide->stage.point = widepoint_first_point;
318    wide->stage.line = draw_pipe_passthrough_line;
319    wide->stage.tri = draw_pipe_passthrough_tri;
320    wide->stage.flush = widepoint_flush;
321    wide->stage.reset_stipple_counter = widepoint_reset_stipple_counter;
322    wide->stage.destroy = widepoint_destroy;
323 
324    if (!draw_alloc_temp_verts( &wide->stage, 4 ))
325       goto fail;
326 
327    wide->sprite_coord_semantic =
328       draw->pipe->screen->get_param(draw->pipe->screen, PIPE_CAP_TGSI_TEXCOORD)
329       ?
330       TGSI_SEMANTIC_TEXCOORD : TGSI_SEMANTIC_GENERIC;
331 
332    return &wide->stage;
333 
334  fail:
335    if (wide)
336       wide->stage.destroy( &wide->stage );
337 
338    return NULL;
339 }
340