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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 "main/macros.h"
#include "draw_private.h"
struct offset_stage {
struct prim_stage stage;
GLuint hw_data_offset;
GLfloat scale;
GLfloat units;
};
static INLINE struct offset_stage *offset_stage( struct prim_stage *stage )
{
return (struct offset_stage *)stage;
}
static void offset_begin( struct prim_stage *stage )
{
struct offset_stage *offset = offset_stage(stage);
offset->units = stage->draw->setup.offset_units;
offset->scale = stage->draw->setup.offset_scale;
stage->next->begin( stage->next );
}
/**
* Offset tri Z. Some hardware can handle this, but not usually when
* doing unfilled rendering.
*/
static void do_offset_tri( struct prim_stage *stage,
struct prim_header *header )
{
struct offset_stage *offset = offset_stage(stage);
GLfloat inv_det = 1.0 / header->det;
/* Window coords:
*/
GLfloat *v0 = header->v[0]->data[0];
GLfloat *v1 = header->v[1]->data[0];
GLfloat *v2 = header->v[2]->data[0];
/* edge vectors e = v0 - v2, f = v1 - v2 */
GLfloat ex = v0[0] - v2[2];
GLfloat ey = v0[1] - v2[2];
GLfloat ez = v0[2] - v2[2];
GLfloat fx = v1[0] - v2[2];
GLfloat fy = v1[1] - v2[2];
GLfloat fz = v1[2] - v2[2];
/* (a,b) = cross(e,f).xy */
GLfloat a = ey*fz - ez*fy;
GLfloat b = ez*fx - ex*fz;
GLfloat dzdx = FABSF(a * inv_det);
GLfloat dzdy = FABSF(b * inv_det);
GLfloat zoffset = offset->units + MAX2(dzdx, dzdy) * offset->scale;
/*
* Note: we're applying the offset and clamping per-vertex.
* Ideally, the offset is applied per-fragment prior to fragment shading.
*/
v0[2] = CLAMP(v0[2] + zoffset, 0.0, 1.0);
v1[2] = CLAMP(v1[2] + zoffset, 0.0, 1.0);
v2[2] = CLAMP(v2[2] + zoffset, 0.0, 1.0);
stage->next->tri( stage->next, header );
}
static void offset_tri( struct prim_stage *stage,
struct prim_header *header )
{
struct prim_header tmp;
tmp.det = header->det;
tmp.v[0] = dup_vert(stage, header->v[0], 0);
tmp.v[1] = dup_vert(stage, header->v[1], 1);
tmp.v[2] = dup_vert(stage, header->v[2], 2);
do_offset_tri( stage, &tmp );
}
static void offset_line( struct prim_stage *stage,
struct prim_header *header )
{
stage->next->line( stage->next, header );
}
static void offset_point( struct prim_stage *stage,
struct prim_header *header )
{
stage->next->point( stage->next, header );
}
static void offset_end( struct prim_stage *stage )
{
stage->next->end( stage->next );
}
struct prim_stage *prim_offset( struct draw_context *draw )
{
struct offset_stage *offset = CALLOC_STRUCT(offset_stage);
prim_alloc_tmps( &offset->stage, 3 );
offset->stage.draw = draw;
offset->stage.next = NULL;
offset->stage.begin = offset_begin;
offset->stage.point = offset_point;
offset->stage.line = offset_line;
offset->stage.tri = offset_tri;
offset->stage.end = offset_end;
return &offset->stage;
}
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