src/mesa/pipe/draw/draw_vertex.c

   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,
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  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
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  24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27
  28 /*
  29  * Functions for specifying the post-transformation vertex layout.
  30  *
  31  * Author:
  32  *    Brian Paul
  33  *    Keith Whitwell
  34  */
  35
  36
  37 #include "pipe/p_defines.h"
  38 #include "pipe/p_context.h"
  39 #include "pipe/p_winsys.h"
  40 #include "pipe/p_util.h"
  41
  42 #include "pipe/draw/draw_private.h"
  43 #include "pipe/draw/draw_context.h"
  44 #include "pipe/draw/draw_vertex.h"
  45
  46
  47 static INLINE void
  48 emit_vertex_attr(struct vertex_info *vinfo,
  49                  attrib_format format, interp_mode interp)
  50 {
  51    const uint n = vinfo->num_attribs;
  52    vinfo->interp_mode[n] = interp;
  53    vinfo->format[n] = format;
  54    vinfo->num_attribs++;
  55 }
  56
  57
  58 /**
  59  * Compute the size of a vertex, in dwords/floats, to update the
  60  * vinfo->size field.
  61  */
  62 void
  63 draw_compute_vertex_size(struct vertex_info *vinfo)
  64 {
  65    uint i;
  66
  67    vinfo->size = 0;
  68    for (i = 0; i < vinfo->num_attribs; i++) {
  69       switch (vinfo->format[i]) {
  70       case FORMAT_OMIT:
  71          break;
  72       case FORMAT_4UB:
  73          /* fall-through */
  74       case FORMAT_1F:
  75          vinfo->size += 1;
  76          break;
  77       case FORMAT_2F:
  78          vinfo->size += 2;
  79          break;
  80       case FORMAT_3F:
  81          vinfo->size += 3;
  82          break;
  83       case FORMAT_4F:
  84       case FORMAT_4F_VIEWPORT:
  85          vinfo->size += 4;
  86          break;
  87       default:
  88          assert(0);
  89       }
  90    }
  91 }
  92
  93
  94 /**
  95  * Tell the drawing module about the layout of post-transformation vertices
  96  */
  97 void
  98 draw_set_vertex_attributes( struct draw_context *draw,
  99                             const uint *slot_to_vf_attr,
 100                             const interp_mode *interps,
 101                             unsigned nr_attrs )
 102 {
 103    struct vertex_info *vinfo = &draw->vertex_info;
 104    unsigned i;
 105
 106 #if 0
 107    assert(slot_to_vf_attr[0] == TGSI_ATTRIB_POS);
 108 #endif
 109
 110    memset(vinfo, 0, sizeof(*vinfo));
 111
 112    /*
 113     * First three attribs are always the same: header, clip pos, winpos
 114     */
 115    emit_vertex_attr(vinfo, FORMAT_1F, INTERP_NONE);
 116    emit_vertex_attr(vinfo, FORMAT_4F, INTERP_LINEAR);
 117    emit_vertex_attr(vinfo, FORMAT_4F_VIEWPORT, INTERP_LINEAR);
 118
 119    /*
 120     * Remaining attribs (color, texcoords, etc)
 121     */
 122    for (i = 1; i < nr_attrs; i++) {
 123       emit_vertex_attr(vinfo, FORMAT_4F, interps[i]);
 124    }
 125
 126    draw_compute_vertex_size(vinfo);
 127 }
 128
 129
 130 /**
 131  * This function is used to tell the draw module about attributes
 132  * (like colors) that need to be selected based on front/back face
 133  * orientation.
 134  *
 135  * The logic is:
 136  *    if (polygon is back-facing) {
 137  *       vertex->attrib[front0] = vertex->attrib[back0];
 138  *       vertex->attrib[front1] = vertex->attrib[back1];
 139  *    }
 140  *
 141  * \param front0  first attrib to replace if the polygon is back-facing
 142  * \param back0  first attrib to copy if the polygon is back-facing
 143  * \param front1  second attrib to replace if the polygon is back-facing
 144  * \param back1  second attrib to copy if the polygon is back-facing
 145  *
 146  * Pass -1 to disable two-sided attributes.
 147  */
 148 void
 149 draw_set_twoside_attributes(struct draw_context *draw,
 150                             uint front0, uint back0,
 151                             uint front1, uint back1)
 152 {
 153    /* XXX we could alternately pass an array of front/back attribs if there's
 154     * ever need for more than two.  One could imagine a shader extension
 155     * that allows arbitrary attributes to be selected based on polygon
 156     * orientation...
 157     */
 158    draw->attrib_front0 = front0;
 159    draw->attrib_back0 = back0;
 160    draw->attrib_front1 = front1;
 161    draw->attrib_back1 = back1;
 162 }