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
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   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
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  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/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_PSIZE:
  69          /* fall-through */
  70       case FORMAT_1F:
  71          vinfo->size += 1;
  72          break;
  73       case FORMAT_2F:
  74          vinfo->size += 2;
  75          break;
  76       case FORMAT_3F:
  77          vinfo->size += 3;
  78          break;
  79       case FORMAT_4F:
  80          vinfo->size += 4;
  81          break;
  82       default:
  83          assert(0);
  84       }
  85    }
  86
  87    assert(vinfo->size * 4 <= MAX_VERTEX_SIZE);
  88 }
  89
  90
  91 /**
  92  * Tell the drawing module about the contents of post-transformation vertices.
  93  * Note that the vertex attribute format info isn't used by 'draw'; all
  94  * attributes are handled as float[4].  But when the driver emits vertices
  95  * it'll use that info.
  96  * We _do_ care about the number of attributes and their interpolation modes.
  97  */
  98 void
  99 draw_set_vertex_info( struct draw_context *draw,
 100                       const struct vertex_info *info)
 101 {
 102    assert(info->interp_mode[0] == INTERP_LINEAR); /* should be vert pos */
 103    assert(info->num_attribs <= PIPE_MAX_SHADER_OUTPUTS);
 104
 105    memcpy(&draw->vertex_info, info, sizeof(*info));
 106
 107    /* Need to know vertex size (in words) for vertex copying elsewhere.
 108     * Four words per attribute, plus vertex header (uint) and clip
 109     * position (float[4]).
 110     */
 111    draw->vertex_info.size = draw->vertex_info.num_attribs * 4 + 5;
 112 }
 113
 114
 115 /**
 116  * This function is used to tell the draw module about attributes
 117  * (like colors) that need to be selected based on front/back face
 118  * orientation.
 119  *
 120  * The logic is:
 121  *    if (polygon is back-facing) {
 122  *       vertex->attrib[front0] = vertex->attrib[back0];
 123  *       vertex->attrib[front1] = vertex->attrib[back1];
 124  *    }
 125  *
 126  * \param front0  first attrib to replace if the polygon is back-facing
 127  * \param back0  first attrib to copy if the polygon is back-facing
 128  * \param front1  second attrib to replace if the polygon is back-facing
 129  * \param back1  second attrib to copy if the polygon is back-facing
 130  *
 131  * Pass -1 to disable two-sided attributes.
 132  */
 133 void
 134 draw_set_twoside_attributes(struct draw_context *draw,
 135                             uint front0, uint back0,
 136                             uint front1, uint back1)
 137 {
 138    /* XXX we could alternately pass an array of front/back attribs if there's
 139     * ever need for more than two.  One could imagine a shader extension
 140     * that allows arbitrary attributes to be selected based on polygon
 141     * orientation...
 142     */
 143    draw->attrib_front0 = front0;
 144    draw->attrib_back0 = back0;
 145    draw->attrib_front1 = front1;
 146    draw->attrib_back1 = back1;
 147 }