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