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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 "pipe/p_util.h"
#include "pipe/p_defines.h"
#include "draw_private.h"
struct twoside_stage {
struct draw_stage stage;
float sign; /**< +1 or -1 */
};
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->rasterizer->front_winding == PIPE_WINDING_CCW) ? -1.0f : 1.0f;
stage->next->begin( stage->next );
}
static INLINE void copy_attrib( unsigned attr_dst,
unsigned attr_src,
struct vertex_header *v )
{
COPY_4FV(v->data[attr_dst], v->data[attr_src]);
}
/**
* Copy back color(s) to front color(s).
*/
static 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 );
const struct draw_context *draw = twoside->stage.draw;
if (draw->attrib_front0 && draw->attrib_back0) {
assert(draw->attrib_back0);
copy_attrib(draw->attrib_front0, draw->attrib_back0, tmp);
}
if (draw->attrib_front1 && draw->attrib_back1) {
assert(draw->attrib_back1);
copy_attrib(draw->attrib_front1, draw->attrib_back1, 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;
tmp.edgeflags = header->edgeflags;
/* 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_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 );
}
static void twoside_reset_stipple_counter( struct draw_stage *stage )
{
stage->next->reset_stipple_counter( 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->stage.reset_stipple_counter = twoside_reset_stipple_counter;
return &twoside->stage;
}
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