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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 "pipe/p_shader_tokens.h"
#include "draw_private.h"
struct twoside_stage {
struct draw_stage stage;
float sign; /**< +1 or -1 */
uint attrib_front0, attrib_back0;
uint attrib_front1, attrib_back1;
};
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);
const struct pipe_shader_state *vs = stage->draw->vertex_shader->state;
uint i;
twoside->attrib_front0 = 0;
twoside->attrib_front1 = 0;
twoside->attrib_back0 = 0;
twoside->attrib_back1 = 0;
/* Find which vertex shader outputs are front/back colors */
for (i = 0; i < vs->num_outputs; i++) {
if (vs->output_semantic_name[i] == TGSI_SEMANTIC_COLOR) {
if (vs->output_semantic_index[i] == 0)
twoside->attrib_front0 = i;
else
twoside->attrib_front1 = i;
}
if (vs->output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
if (vs->output_semantic_index[i] == 0)
twoside->attrib_back0 = i;
else
twoside->attrib_back1 = i;
}
}
if (!twoside->attrib_back0)
twoside->attrib_front0 = 0;
if (!twoside->attrib_back1)
twoside->attrib_front1 = 0;
/*
* 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 );
}
/**
* 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) {
COPY_4FV(tmp->data[twoside->attrib_front0],
tmp->data[twoside->attrib_back0]);
}
if (twoside->attrib_back1) {
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.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 );
}
static void twoside_destroy( struct draw_stage *stage )
{
draw_free_tmps( 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);
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;
twoside->stage.destroy = twoside_destroy;
return &twoside->stage;
}
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