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27 
28 /*
29  * Binning code for points
30  */
31 
32 #include "lp_setup_context.h"
33 #include "util/u_math.h"
34 #include "util/u_memory.h"
35 #include "lp_perf.h"
36 #include "lp_rast.h"
37 #include "lp_state_fs.h"
38 #include "lp_state_setup.h"
39 #include "tgsi/tgsi_scan.h"
40 
41 #define NUM_CHANNELS 4
42 
43 struct point_info {
44    /* x,y deltas */
45    int dy01, dy12;
46    int dx01, dx12;
47 
48    const float (*v0)[4];
49 
50    float (*a0)[4];
51    float (*dadx)[4];
52    float (*dady)[4];
53 };
54 
55 
56 /**
57  * Compute a0 for a constant-valued coefficient (GL_FLAT shading).
58  */
59 static void
constant_coef(struct lp_setup_context * setup,struct point_info * info,unsigned slot,const float value,unsigned i)60 constant_coef(struct lp_setup_context *setup,
61               struct point_info *info,
62               unsigned slot,
63               const float value,
64               unsigned i)
65 {
66    info->a0[slot][i] = value;
67    info->dadx[slot][i] = 0.0f;
68    info->dady[slot][i] = 0.0f;
69 }
70 
71 
72 static void
point_persp_coeff(struct lp_setup_context * setup,const struct point_info * info,unsigned slot,unsigned i)73 point_persp_coeff(struct lp_setup_context *setup,
74                   const struct point_info *info,
75                   unsigned slot,
76                   unsigned i)
77 {
78    /*
79     * Fragment shader expects pre-multiplied w for LP_INTERP_PERSPECTIVE. A
80     * better stratergy would be to take the primitive in consideration when
81     * generating the fragment shader key, and therefore avoid the per-fragment
82     * perspective divide.
83     */
84 
85    float w0 = info->v0[0][3];
86 
87    assert(i < 4);
88 
89    info->a0[slot][i] = info->v0[slot][i]*w0;
90    info->dadx[slot][i] = 0.0f;
91    info->dady[slot][i] = 0.0f;
92 }
93 
94 
95 /**
96  * Setup automatic texcoord coefficients (for sprite rendering).
97  * \param slot  the vertex attribute slot to setup
98  * \param i  the attribute channel in [0,3]
99  * \param sprite_coord_origin  one of PIPE_SPRITE_COORD_x
100  * \param perspective  does the shader expects pre-multiplied w, i.e.,
101  *    LP_INTERP_PERSPECTIVE is specified in the shader key
102  */
103 static void
texcoord_coef(struct lp_setup_context * setup,const struct point_info * info,unsigned slot,unsigned i,unsigned sprite_coord_origin,boolean perspective)104 texcoord_coef(struct lp_setup_context *setup,
105               const struct point_info *info,
106               unsigned slot,
107               unsigned i,
108               unsigned sprite_coord_origin,
109               boolean perspective)
110 {
111    float w0 = info->v0[0][3];
112 
113    assert(i < 4);
114 
115    if (i == 0) {
116       float dadx = FIXED_ONE / (float)info->dx12;
117       float dady =  0.0f;
118       float x0 = info->v0[0][0] - setup->pixel_offset;
119       float y0 = info->v0[0][1] - setup->pixel_offset;
120 
121       info->dadx[slot][0] = dadx;
122       info->dady[slot][0] = dady;
123       info->a0[slot][0] = 0.5 - (dadx * x0 + dady * y0);
124 
125       if (perspective) {
126          info->dadx[slot][0] *= w0;
127          info->dady[slot][0] *= w0;
128          info->a0[slot][0] *= w0;
129       }
130    }
131    else if (i == 1) {
132       float dadx = 0.0f;
133       float dady = FIXED_ONE / (float)info->dx12;
134       float x0 = info->v0[0][0] - setup->pixel_offset;
135       float y0 = info->v0[0][1] - setup->pixel_offset;
136 
137       if (sprite_coord_origin == PIPE_SPRITE_COORD_LOWER_LEFT) {
138          dady = -dady;
139       }
140 
141       info->dadx[slot][1] = dadx;
142       info->dady[slot][1] = dady;
143       info->a0[slot][1] = 0.5 - (dadx * x0 + dady * y0);
144 
145       if (perspective) {
146          info->dadx[slot][1] *= w0;
147          info->dady[slot][1] *= w0;
148          info->a0[slot][1] *= w0;
149       }
150    }
151    else if (i == 2) {
152       info->a0[slot][2] = 0.0f;
153       info->dadx[slot][2] = 0.0f;
154       info->dady[slot][2] = 0.0f;
155    }
156    else {
157       info->a0[slot][3] = perspective ? w0 : 1.0f;
158       info->dadx[slot][3] = 0.0f;
159       info->dady[slot][3] = 0.0f;
160    }
161 }
162 
163 
164 /**
165  * Special coefficient setup for gl_FragCoord.
166  * X and Y are trivial
167  * Z and W are copied from position_coef which should have already been computed.
168  * We could do a bit less work if we'd examine gl_FragCoord's swizzle mask.
169  */
170 static void
setup_point_fragcoord_coef(struct lp_setup_context * setup,struct point_info * info,unsigned slot,unsigned usage_mask)171 setup_point_fragcoord_coef(struct lp_setup_context *setup,
172                            struct point_info *info,
173                            unsigned slot,
174                            unsigned usage_mask)
175 {
176    /*X*/
177    if (usage_mask & TGSI_WRITEMASK_X) {
178       info->a0[slot][0] = 0.0;
179       info->dadx[slot][0] = 1.0;
180       info->dady[slot][0] = 0.0;
181    }
182 
183    /*Y*/
184    if (usage_mask & TGSI_WRITEMASK_Y) {
185       info->a0[slot][1] = 0.0;
186       info->dadx[slot][1] = 0.0;
187       info->dady[slot][1] = 1.0;
188    }
189 
190    /*Z*/
191    if (usage_mask & TGSI_WRITEMASK_Z) {
192       constant_coef(setup, info, slot, info->v0[0][2], 2);
193    }
194 
195    /*W*/
196    if (usage_mask & TGSI_WRITEMASK_W) {
197       constant_coef(setup, info, slot, info->v0[0][3], 3);
198    }
199 }
200 
201 
202 /**
203  * Compute the point->coef[] array dadx, dady, a0 values.
204  */
205 static void
setup_point_coefficients(struct lp_setup_context * setup,struct point_info * info)206 setup_point_coefficients( struct lp_setup_context *setup,
207                           struct point_info *info)
208 {
209    const struct lp_setup_variant_key *key = &setup->setup.variant->key;
210    const struct lp_fragment_shader *shader = setup->fs.current.variant->shader;
211    unsigned fragcoord_usage_mask = TGSI_WRITEMASK_XYZ;
212    unsigned slot;
213 
214    /* setup interpolation for all the remaining attributes:
215     */
216    for (slot = 0; slot < key->num_inputs; slot++) {
217       unsigned vert_attr = key->inputs[slot].src_index;
218       unsigned usage_mask = key->inputs[slot].usage_mask;
219       enum lp_interp interp = key->inputs[slot].interp;
220       boolean perspective = !!(interp == LP_INTERP_PERSPECTIVE);
221       unsigned i;
222 
223       if (perspective & usage_mask) {
224          fragcoord_usage_mask |= TGSI_WRITEMASK_W;
225       }
226 
227       switch (interp) {
228       case LP_INTERP_POSITION:
229          /*
230           * The generated pixel interpolators will pick up the coeffs from
231           * slot 0, so all need to ensure that the usage mask is covers all
232           * usages.
233           */
234          fragcoord_usage_mask |= usage_mask;
235          break;
236 
237       case LP_INTERP_LINEAR:
238          /* Sprite tex coords may use linear interpolation someday */
239          /* fall-through */
240       case LP_INTERP_PERSPECTIVE:
241          /* check if the sprite coord flag is set for this attribute.
242           * If so, set it up so it up so x and y vary from 0 to 1.
243           */
244          if (shader->info.base.input_semantic_name[slot] == TGSI_SEMANTIC_GENERIC) {
245             unsigned semantic_index = shader->info.base.input_semantic_index[slot];
246             /* Note that sprite_coord enable is a bitfield of
247              * PIPE_MAX_SHADER_OUTPUTS bits.
248              */
249             if (semantic_index < PIPE_MAX_SHADER_OUTPUTS &&
250                 (setup->sprite_coord_enable & (1 << semantic_index))) {
251                for (i = 0; i < NUM_CHANNELS; i++) {
252                   if (usage_mask & (1 << i)) {
253                      texcoord_coef(setup, info, slot + 1, i,
254                                    setup->sprite_coord_origin,
255                                    perspective);
256                   }
257                }
258                break;
259             }
260          }
261          /* fall-through */
262       case LP_INTERP_CONSTANT:
263          for (i = 0; i < NUM_CHANNELS; i++) {
264             if (usage_mask & (1 << i)) {
265                if (perspective) {
266                   point_persp_coeff(setup, info, slot+1, i);
267                }
268                else {
269                   constant_coef(setup, info, slot+1, info->v0[vert_attr][i], i);
270                }
271             }
272          }
273          break;
274 
275       case LP_INTERP_FACING:
276          for (i = 0; i < NUM_CHANNELS; i++)
277             if (usage_mask & (1 << i))
278                constant_coef(setup, info, slot+1, 1.0, i);
279          break;
280 
281       default:
282          assert(0);
283          break;
284       }
285    }
286 
287    /* The internal position input is in slot zero:
288     */
289    setup_point_fragcoord_coef(setup, info, 0,
290                               fragcoord_usage_mask);
291 }
292 
293 
294 static INLINE int
subpixel_snap(float a)295 subpixel_snap(float a)
296 {
297    return util_iround(FIXED_ONE * a);
298 }
299 
300 
301 static boolean
try_setup_point(struct lp_setup_context * setup,const float (* v0)[4])302 try_setup_point( struct lp_setup_context *setup,
303                  const float (*v0)[4] )
304 {
305    /* x/y positions in fixed point */
306    const struct lp_setup_variant_key *key = &setup->setup.variant->key;
307    const int sizeAttr = setup->psize;
308    const float size
309       = (setup->point_size_per_vertex && sizeAttr > 0) ? v0[sizeAttr][0]
310       : setup->point_size;
311 
312    /* Point size as fixed point integer, remove rounding errors
313     * and gives minimum width for very small points
314     */
315    int fixed_width = MAX2(FIXED_ONE,
316                           (subpixel_snap(size) + FIXED_ONE/2 - 1) & ~(FIXED_ONE-1));
317 
318    const int x0 = subpixel_snap(v0[0][0] - setup->pixel_offset) - fixed_width/2;
319    const int y0 = subpixel_snap(v0[0][1] - setup->pixel_offset) - fixed_width/2;
320 
321    struct lp_scene *scene = setup->scene;
322    struct lp_rast_triangle *point;
323    unsigned bytes;
324    struct u_rect bbox;
325    unsigned nr_planes = 4;
326    struct point_info info;
327 
328 
329    /* Bounding rectangle (in pixels) */
330    {
331       /* Yes this is necessary to accurately calculate bounding boxes
332        * with the two fill-conventions we support.  GL (normally) ends
333        * up needing a bottom-left fill convention, which requires
334        * slightly different rounding.
335        */
336       int adj = (setup->pixel_offset != 0) ? 1 : 0;
337 
338       bbox.x0 = (x0 + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
339       bbox.x1 = (x0 + fixed_width + (FIXED_ONE-1) + adj) >> FIXED_ORDER;
340       bbox.y0 = (y0 + (FIXED_ONE-1)) >> FIXED_ORDER;
341       bbox.y1 = (y0 + fixed_width + (FIXED_ONE-1)) >> FIXED_ORDER;
342 
343       /* Inclusive coordinates:
344        */
345       bbox.x1--;
346       bbox.y1--;
347    }
348 
349    if (!u_rect_test_intersection(&setup->draw_region, &bbox)) {
350       if (0) debug_printf("offscreen\n");
351       LP_COUNT(nr_culled_tris);
352       return TRUE;
353    }
354 
355    u_rect_find_intersection(&setup->draw_region, &bbox);
356 
357    point = lp_setup_alloc_triangle(scene,
358                                    key->num_inputs,
359                                    nr_planes,
360                                    &bytes);
361    if (!point)
362       return FALSE;
363 
364 #ifdef DEBUG
365    point->v[0][0] = v0[0][0];
366    point->v[0][1] = v0[0][1];
367 #endif
368 
369    info.v0 = v0;
370    info.dx01 = 0;
371    info.dx12 = fixed_width;
372    info.dy01 = fixed_width;
373    info.dy12 = 0;
374    info.a0 = GET_A0(&point->inputs);
375    info.dadx = GET_DADX(&point->inputs);
376    info.dady = GET_DADY(&point->inputs);
377 
378    /* Setup parameter interpolants:
379     */
380    setup_point_coefficients(setup, &info);
381 
382    point->inputs.frontfacing = TRUE;
383    point->inputs.disable = FALSE;
384    point->inputs.opaque = FALSE;
385 
386    {
387       struct lp_rast_plane *plane = GET_PLANES(point);
388 
389       plane[0].dcdx = -1;
390       plane[0].dcdy = 0;
391       plane[0].c = 1-bbox.x0;
392       plane[0].eo = 1;
393 
394       plane[1].dcdx = 1;
395       plane[1].dcdy = 0;
396       plane[1].c = bbox.x1+1;
397       plane[1].eo = 0;
398 
399       plane[2].dcdx = 0;
400       plane[2].dcdy = 1;
401       plane[2].c = 1-bbox.y0;
402       plane[2].eo = 1;
403 
404       plane[3].dcdx = 0;
405       plane[3].dcdy = -1;
406       plane[3].c = bbox.y1+1;
407       plane[3].eo = 0;
408    }
409 
410    return lp_setup_bin_triangle(setup, point, &bbox, nr_planes);
411 }
412 
413 
414 static void
lp_setup_point(struct lp_setup_context * setup,const float (* v0)[4])415 lp_setup_point(struct lp_setup_context *setup,
416                const float (*v0)[4])
417 {
418    if (!try_setup_point( setup, v0 ))
419    {
420       if (!lp_setup_flush_and_restart(setup))
421          return;
422 
423       if (!try_setup_point( setup, v0 ))
424          return;
425    }
426 }
427 
428 
429 void
lp_setup_choose_point(struct lp_setup_context * setup)430 lp_setup_choose_point( struct lp_setup_context *setup )
431 {
432    setup->point = lp_setup_point;
433 }
434 
435 
436