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