src/mesa/tnl/t_vb_cull.c

   1 /*
   2  * Mesa 3-D graphics library
   3  * Version:  6.5
   4  *
   5  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the "Software"),
   9  * to deal in the Software without restriction, including without limitation
  10  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11  * and/or sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included
  15  * in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  21  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  22  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *    Keith Whitwell <keith@tungstengraphics.com>
  26  */
  27
  28
  29 #include "glheader.h"
  30 #include "colormac.h"
  31 #include "context.h"
  32 #include "macros.h"
  33 #include "imports.h"
  34 #include "mtypes.h"
  35
  36 #include "math/m_xform.h"
  37
  38 #include "t_context.h"
  39 #include "t_pipeline.h"
  40
  41
  42
  43 /* EXT_vertex_cull.  Not really a big win, but probably depends on
  44  * your application.  This stage not included in the default pipeline.
  45  */
  46 static GLboolean run_cull_stage( GLcontext *ctx,
  47                                  struct tnl_pipeline_stage *stage )
  48 {
  49    TNLcontext *tnl = TNL_CONTEXT(ctx);
  50    struct vertex_buffer *VB = &tnl->vb;
  51
  52    const GLfloat a = ctx->Transform.CullObjPos[0];
  53    const GLfloat b = ctx->Transform.CullObjPos[1];
  54    const GLfloat c = ctx->Transform.CullObjPos[2];
  55    GLfloat *norm = (GLfloat *)VB->AttribPtr[_TNL_ATTRIB_NORMAL]->data;
  56    GLuint stride = VB->AttribPtr[_TNL_ATTRIB_NORMAL]->stride;
  57    GLuint count = VB->Count;
  58    GLuint i;
  59
  60    if (ctx->VertexProgram._Current ||
  61        !ctx->Transform.CullVertexFlag)
  62       return GL_TRUE;
  63
  64    VB->ClipOrMask &= ~CLIP_CULL_BIT;
  65    VB->ClipAndMask |= CLIP_CULL_BIT;
  66
  67    for (i = 0 ; i < count ; i++) {
  68       GLfloat dp = (norm[0] * a +
  69                     norm[1] * b +
  70                     norm[2] * c);
  71
  72       if (dp < 0) {
  73          VB->ClipMask[i] |= CLIP_CULL_BIT;
  74          VB->ClipOrMask |= CLIP_CULL_BIT;
  75       }
  76       else {
  77          VB->ClipMask[i] &= ~CLIP_CULL_BIT;
  78          VB->ClipAndMask &= ~CLIP_CULL_BIT;
  79       }
  80
  81       STRIDE_F(norm, stride);
  82    }
  83
  84    return !(VB->ClipAndMask & CLIP_CULL_BIT);
  85 }
  86
  87
  88
  89 const struct tnl_pipeline_stage _tnl_vertex_cull_stage =
  90 {
  91    "EXT_cull_vertex",
  92    NULL,                        /* private data */
  93    NULL,                                /* ctr */
  94    NULL,                                /* destructor */
  95    NULL,
  96    run_cull_stage               /* run -- initially set to init */
  97 };