src/gallium/auxiliary/draw/draw_pipe_wide_point.c

   1 /**************************************************************************
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   3  * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
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  27
  28 /* Authors:  Keith Whitwell <keith@tungstengraphics.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 state tracker could create a GS to do
  51  * most/all of this.
  52  */
  53
  54
  55 #include "util/u_math.h"
  56 #include "util/u_memory.h"
  57 #include "pipe/p_defines.h"
  58 #include "pipe/p_shader_tokens.h"
  59 #include "draw_vs.h"
  60 #include "draw_pipe.h"
  61
  62
  63 struct widepoint_stage {
  64    struct draw_stage stage;
  65
  66    float half_point_size;
  67    float point_size_min;
  68    float point_size_max;
  69
  70    float xbias;
  71    float ybias;
  72
  73    uint texcoord_slot[PIPE_MAX_SHADER_OUTPUTS];
  74    uint texcoord_mode[PIPE_MAX_SHADER_OUTPUTS];
  75    uint num_texcoords;
  76
  77    int psize_slot;
  78
  79    int point_coord_fs_input;  /**< input for pointcoord */
  80 };
  81
  82
  83
  84 static INLINE struct widepoint_stage *
  85 widepoint_stage( struct draw_stage *stage )
  86 {
  87    return (struct widepoint_stage *)stage;
  88 }
  89
  90
  91 /**
  92  * Set the vertex texcoords for sprite mode.
  93  * Coords may be left untouched or set to a right-side-up or upside-down
  94  * orientation.
  95  */
  96 static void set_texcoords(const struct widepoint_stage *wide,
  97                           struct vertex_header *v, const float tc[4])
  98 {
  99    uint i;
 100    for (i = 0; i < wide->num_texcoords; i++) {
 101       if (wide->texcoord_mode[i] != PIPE_SPRITE_COORD_NONE) {
 102          uint j = wide->texcoord_slot[i];
 103          v->data[j][0] = tc[0];
 104          if (wide->texcoord_mode[i] == PIPE_SPRITE_COORD_LOWER_LEFT)
 105             v->data[j][1] = 1.0f - tc[1];
 106          else
 107             v->data[j][1] = tc[1];
 108          v->data[j][2] = tc[2];
 109          v->data[j][3] = tc[3];
 110       }
 111    }
 112
 113    if (wide->point_coord_fs_input >= 0) {
 114       /* put gl_PointCoord into the extra vertex slot */
 115       uint slot = wide->stage.draw->extra_shader_outputs.slot;
 116       v->data[slot][0] = tc[0];
 117       v->data[slot][1] = tc[1];
 118       v->data[slot][2] = 0.0F;
 119       v->data[slot][3] = 1.0F;
 120    }
 121 }
 122
 123
 124 /* If there are lots of sprite points (and why wouldn't there be?) it
 125  * would probably be more sensible to change hardware setup to
 126  * optimize this rather than doing the whole thing in software like
 127  * this.
 128  */
 129 static void widepoint_point( struct draw_stage *stage,
 130                              struct prim_header *header )
 131 {
 132    const struct widepoint_stage *wide = widepoint_stage(stage);
 133    const unsigned pos = draw_current_shader_position_output(stage->draw);
 134    const boolean sprite = (boolean) stage->draw->rasterizer->point_sprite;
 135    float half_size;
 136    float left_adj, right_adj, bot_adj, top_adj;
 137
 138    struct prim_header tri;
 139
 140    /* four dups of original vertex */
 141    struct vertex_header *v0 = dup_vert(stage, header->v[0], 0);
 142    struct vertex_header *v1 = dup_vert(stage, header->v[0], 1);
 143    struct vertex_header *v2 = dup_vert(stage, header->v[0], 2);
 144    struct vertex_header *v3 = dup_vert(stage, header->v[0], 3);
 145
 146    float *pos0 = v0->data[pos];
 147    float *pos1 = v1->data[pos];
 148    float *pos2 = v2->data[pos];
 149    float *pos3 = v3->data[pos];
 150
 151    /* point size is either per-vertex or fixed size */
 152    if (wide->psize_slot >= 0) {
 153       half_size = header->v[0]->data[wide->psize_slot][0];
 154
 155       /* XXX: temporary -- do this in the vertex shader??
 156        */
 157       half_size = CLAMP(half_size,
 158                         wide->point_size_min,
 159                         wide->point_size_max);
 160
 161       half_size *= 0.5f;
 162    }
 163    else {
 164       half_size = wide->half_point_size;
 165    }
 166
 167    left_adj = -half_size + wide->xbias;
 168    right_adj = half_size + wide->xbias;
 169    bot_adj = half_size + wide->ybias;
 170    top_adj = -half_size + wide->ybias;
 171
 172    pos0[0] += left_adj;
 173    pos0[1] += top_adj;
 174
 175    pos1[0] += left_adj;
 176    pos1[1] += bot_adj;
 177
 178    pos2[0] += right_adj;
 179    pos2[1] += top_adj;
 180
 181    pos3[0] += right_adj;
 182    pos3[1] += bot_adj;
 183
 184    if (sprite) {
 185       static const float tex00[4] = { 0, 0, 0, 1 };
 186       static const float tex01[4] = { 0, 1, 0, 1 };
 187       static const float tex11[4] = { 1, 1, 0, 1 };
 188       static const float tex10[4] = { 1, 0, 0, 1 };
 189       set_texcoords( wide, v0, tex00 );
 190       set_texcoords( wide, v1, tex01 );
 191       set_texcoords( wide, v2, tex10 );
 192       set_texcoords( wide, v3, tex11 );
 193    }
 194
 195    tri.det = header->det;  /* only the sign matters */
 196    tri.v[0] = v0;
 197    tri.v[1] = v2;
 198    tri.v[2] = v3;
 199    stage->next->tri( stage->next, &tri );
 200
 201    tri.v[0] = v0;
 202    tri.v[1] = v3;
 203    tri.v[2] = v1;
 204    stage->next->tri( stage->next, &tri );
 205 }
 206
 207
 208 static int
 209 find_pntc_input_attrib(struct draw_context *draw)
 210 {
 211    /* Scan the fragment program's input decls to find the pointcoord
 212     * attribute.  The xy components will store the point coord.
 213     */
 214    return 0; /* XXX fix this */
 215 }
 216
 217
 218 static void widepoint_first_point( struct draw_stage *stage,
 219                               struct prim_header *header )
 220 {
 221    struct widepoint_stage *wide = widepoint_stage(stage);
 222    struct draw_context *draw = stage->draw;
 223
 224    wide->half_point_size = 0.5f * draw->rasterizer->point_size;
 225    wide->point_size_min = draw->rasterizer->point_size_min;
 226    wide->point_size_max = draw->rasterizer->point_size_max;
 227    wide->xbias = 0.0;
 228    wide->ybias = 0.0;
 229
 230    if (draw->rasterizer->gl_rasterization_rules) {
 231       wide->xbias = 0.125;
 232    }
 233
 234    /* XXX we won't know the real size if it's computed by the vertex shader! */
 235    if ((draw->rasterizer->point_size > draw->pipeline.wide_point_threshold) ||
 236        (draw->rasterizer->point_sprite && draw->pipeline.point_sprite)) {
 237       stage->point = widepoint_point;
 238    }
 239    else {
 240       stage->point = draw_pipe_passthrough_point;
 241    }
 242
 243    if (draw->rasterizer->point_sprite) {
 244       /* find vertex shader texcoord outputs */
 245       const struct draw_vertex_shader *vs = draw->vs.vertex_shader;
 246       uint i, j = 0;
 247       for (i = 0; i < vs->info.num_outputs; i++) {
 248          if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_GENERIC) {
 249             wide->texcoord_slot[j] = i;
 250             wide->texcoord_mode[j] = draw->rasterizer->sprite_coord_mode[j];
 251             j++;
 252          }
 253       }
 254       wide->num_texcoords = j;
 255
 256       /* find fragment shader PointCoord input */
 257       wide->point_coord_fs_input = find_pntc_input_attrib(draw);
 258
 259       /* setup extra vp output (point coord implemented as a texcoord) */
 260       draw->extra_shader_outputs.semantic_name = TGSI_SEMANTIC_GENERIC;
 261       draw->extra_shader_outputs.semantic_index = 0;
 262       draw->extra_shader_outputs.slot = draw_current_shader_outputs(draw);
 263    }
 264    else {
 265       wide->point_coord_fs_input = -1;
 266       draw->extra_shader_outputs.slot = 0;
 267    }
 268
 269    wide->psize_slot = -1;
 270    if (draw->rasterizer->point_size_per_vertex) {
 271       /* find PSIZ vertex output */
 272       const struct draw_vertex_shader *vs = draw->vs.vertex_shader;
 273       uint i;
 274       for (i = 0; i < vs->info.num_outputs; i++) {
 275          if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_PSIZE) {
 276             wide->psize_slot = i;
 277             break;
 278          }
 279       }
 280    }
 281
 282    stage->point( stage, header );
 283 }
 284
 285
 286 static void widepoint_flush( struct draw_stage *stage, unsigned flags )
 287 {
 288    stage->point = widepoint_first_point;
 289    stage->next->flush( stage->next, flags );
 290    stage->draw->extra_shader_outputs.slot = 0;
 291 }
 292
 293
 294 static void widepoint_reset_stipple_counter( struct draw_stage *stage )
 295 {
 296    stage->next->reset_stipple_counter( stage->next );
 297 }
 298
 299
 300 static void widepoint_destroy( struct draw_stage *stage )
 301 {
 302    draw_free_temp_verts( stage );
 303    FREE( stage );
 304 }
 305
 306
 307 struct draw_stage *draw_wide_point_stage( struct draw_context *draw )
 308 {
 309    struct widepoint_stage *wide = CALLOC_STRUCT(widepoint_stage);
 310    if (wide == NULL)
 311       goto fail;
 312
 313    if (!draw_alloc_temp_verts( &wide->stage, 4 ))
 314       goto fail;
 315
 316    wide->stage.draw = draw;
 317    wide->stage.name = "wide-point";
 318    wide->stage.next = NULL;
 319    wide->stage.point = widepoint_first_point;
 320    wide->stage.line = draw_pipe_passthrough_line;
 321    wide->stage.tri = draw_pipe_passthrough_tri;
 322    wide->stage.flush = widepoint_flush;
 323    wide->stage.reset_stipple_counter = widepoint_reset_stipple_counter;
 324    wide->stage.destroy = widepoint_destroy;
 325
 326    return &wide->stage;
 327
 328  fail:
 329    if (wide)
 330       wide->stage.destroy( &wide->stage );
 331
 332    return NULL;
 333 }