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/**************************************************************************
*
* Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
* 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 TUNGSTEN GRAPHICS 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 <keith@tungstengraphics.com>
*/
#include "main/imports.h"
#include "pipe/p_defines.h"
#include "draw_private.h"
struct twoside_stage {
struct draw_stage stage;
GLfloat sign; /**< +1 or -1 */
const GLuint *lookup;
};
static INLINE struct twoside_stage *twoside_stage( struct draw_stage *stage )
{
return (struct twoside_stage *)stage;
}
static void twoside_begin( struct draw_stage *stage )
{
struct twoside_stage *twoside = twoside_stage(stage);
/*
* 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->setup.front_winding == PIPE_WINDING_CCW) ? 1 : -1;
stage->next->begin( stage->next );
}
static INLINE void copy_color( GLuint attr_dst,
GLuint attr_src,
struct vertex_header *v )
{
if (attr_dst && attr_src) {
memcpy( v->data[attr_dst],
v->data[attr_src],
sizeof(v->data[0]) );
}
}
static struct vertex_header *copy_bfc( struct twoside_stage *twoside,
const struct vertex_header *v,
GLuint idx )
{
struct vertex_header *tmp = dup_vert( &twoside->stage, v, idx );
copy_color( twoside->lookup[VF_ATTRIB_COLOR0],
twoside->lookup[VF_ATTRIB_BFC0],
tmp );
copy_color( twoside->lookup[VF_ATTRIB_COLOR1],
twoside->lookup[VF_ATTRIB_BFC1],
tmp );
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;
/* copy back colors to front color slots */
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_line( struct draw_stage *stage,
struct prim_header *header )
{
/* pass-through */
stage->next->line( stage->next, header );
}
static void twoside_point( struct draw_stage *stage,
struct prim_header *header )
{
/* pass-through */
stage->next->point( stage->next, header );
}
static void twoside_end( struct draw_stage *stage )
{
/* pass-through */
stage->next->end( stage->next );
}
/**
* Create twoside pipeline stage.
*/
struct draw_stage *draw_twoside_stage( struct draw_context *draw )
{
struct twoside_stage *twoside = CALLOC_STRUCT(twoside_stage);
draw_alloc_tmps( &twoside->stage, 3 );
twoside->stage.draw = draw;
twoside->stage.next = NULL;
twoside->stage.begin = twoside_begin;
twoside->stage.point = twoside_point;
twoside->stage.line = twoside_line;
twoside->stage.tri = twoside_tri;
twoside->stage.end = twoside_end;
twoside->lookup = draw->vf_attr_to_slot;
return &twoside->stage;
}
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