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/**************************************************************************

 *

 * Copyright 2007 VMware, Inc.

 * All Rights Reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, sub license, and/or sell copies of the Software, and to

 * permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice (including the

 * next paragraph) shall be included in all copies or substantial portions

 * of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.

 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR

 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 *

 **************************************************************************/

/* Authors:  Keith Whitwell 

 */

#include "util/u_math.h"

#include "util/u_memory.h"

#include "pipe/p_defines.h"

#include "pipe/p_shader_tokens.h"

#include "draw_vs.h"

#include "draw_pipe.h"

struct twoside_stage {

   struct draw_stage stage;

   float sign;         /**< +1 or -1 */

   int attrib_front0, attrib_back0;

   int attrib_front1, attrib_back1;

};

static INLINE struct twoside_stage *twoside_stage( struct draw_stage *stage )

{

   return (struct twoside_stage *)stage;

}

/**

 * Copy back color(s) to front color(s).

 */

static INLINE struct vertex_header *

copy_bfc( struct twoside_stage *twoside,

          const struct vertex_header *v,

          unsigned idx )

{

   struct vertex_header *tmp = dup_vert( &twoside->stage, v, idx );

   if (twoside->attrib_back0 >= 0 && twoside->attrib_front0 >= 0) {

      COPY_4FV(tmp->data[twoside->attrib_front0],

               tmp->data[twoside->attrib_back0]);

   }

   if (twoside->attrib_back1 >= 0 && twoside->attrib_front1 >= 0) {

      COPY_4FV(tmp->data[twoside->attrib_front1],

               tmp->data[twoside->attrib_back1]);

   }

   return tmp;

}

/* Twoside tri:

 */

static void twoside_tri( struct draw_stage *stage,

			 struct prim_header *header )

{

   struct twoside_stage *twoside = twoside_stage(stage);

   if (header->det * twoside->sign < 0.0) {

      /* this is a back-facing triangle */

      struct prim_header tmp;

      tmp.det = header->det;

      tmp.flags = header->flags;

      tmp.pad = header->pad;

      /* copy back attribs to front attribs */

      tmp.v[0] = copy_bfc(twoside, header->v[0], 0);

      tmp.v[1] = copy_bfc(twoside, header->v[1], 1);

      tmp.v[2] = copy_bfc(twoside, header->v[2], 2);

      stage->next->tri( stage->next, &tmp );

   }

   else {

      stage->next->tri( stage->next, header );

   }

}

static void twoside_first_tri( struct draw_stage *stage,

			       struct prim_header *header )

{

   struct twoside_stage *twoside = twoside_stage(stage);

   const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;

   uint i;

   twoside->attrib_front0 = -1;

   twoside->attrib_front1 = -1;

   twoside->attrib_back0 = -1;

   twoside->attrib_back1 = -1;

   /* Find which vertex shader outputs are front/back colors */

   for (i = 0; i < vs->info.num_outputs; i++) {

      if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_COLOR) {

         if (vs->info.output_semantic_index[i] == 0)

            twoside->attrib_front0 = i;

         else

            twoside->attrib_front1 = i;

      }

      if (vs->info.output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {

         if (vs->info.output_semantic_index[i] == 0)

            twoside->attrib_back0 = i;

         else

            twoside->attrib_back1 = i;

      }

   }

   /*

    * We'll multiply the primitive's determinant by this sign to determine

    * if the triangle is back-facing (negative).

    * sign = -1 for CCW, +1 for CW

    */

   twoside->sign = stage->draw->rasterizer->front_ccw ? -1.0f : 1.0f;

   stage->tri = twoside_tri;

   stage->tri( stage, header );

}

static void twoside_flush( struct draw_stage *stage, unsigned flags )

{

   stage->tri = twoside_first_tri;

   stage->next->flush( stage->next, flags );

}

static void twoside_reset_stipple_counter( struct draw_stage *stage )

{

   stage->next->reset_stipple_counter( stage->next );

}

static void twoside_destroy( struct draw_stage *stage )

{

   draw_free_temp_verts( stage );

   FREE( stage );

}

/**

 * Create twoside pipeline stage.

 */

struct draw_stage *draw_twoside_stage( struct draw_context *draw )

{

   struct twoside_stage *twoside = CALLOC_STRUCT(twoside_stage);

   if (twoside == NULL)

      goto fail;

   twoside->stage.draw = draw;

   twoside->stage.name = "twoside";

   twoside->stage.next = NULL;

   twoside->stage.point = draw_pipe_passthrough_point;

   twoside->stage.line = draw_pipe_passthrough_line;

   twoside->stage.tri = twoside_first_tri;

   twoside->stage.flush = twoside_flush;

   twoside->stage.reset_stipple_counter = twoside_reset_stipple_counter;

   twoside->stage.destroy = twoside_destroy;

   if (!draw_alloc_temp_verts( &twoside->stage, 3 ))

      goto fail;

   return &twoside->stage;

 fail:

   if (twoside)

      twoside->stage.destroy( &twoside->stage );

   return NULL;

}