mesa/src/mesa/pipe/draw/draw_flatshade.c

/**************************************************************************
 * 
 * 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_shader_tokens.h"
#include "draw_private.h"


/** subclass of draw_stage */
struct flat_stage
{
   struct draw_stage stage;

   uint num_color_attribs;
   uint color_attribs[4];  /* front/back primary/secondary colors */
};


static INLINE struct flat_stage *
flat_stage(struct draw_stage *stage)
{
   return (struct flat_stage *) stage;
}


static void flatshade_begin( struct draw_stage *stage )
{
   struct flat_stage *flat = flat_stage(stage);
   const struct pipe_shader_state *vs = stage->draw->vertex_shader->state;
   uint i;

   /* Find which vertex shader outputs are colors, make a list */
   flat->num_color_attribs = 0;
   for (i = 0; i < vs->num_outputs; i++) {
      if (vs->output_semantic_name[i] == TGSI_SEMANTIC_COLOR ||
          vs->output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
         flat->color_attribs[flat->num_color_attribs++] = i;
      }
   }

   stage->next->begin( stage->next );
}


/** Copy all the color attributes from 'src' vertex to 'dst' vertex */
static INLINE void copy_colors( struct draw_stage *stage, 
                                struct vertex_header *dst, 
                                const struct vertex_header *src )
{
   const struct flat_stage *flat = flat_stage(stage);
   uint i;

   /* Look for constant/flat attribs and duplicate from src to dst vertex */
   /* skip attrib[0] which is vert pos */
   for (i = 0; i < flat->num_color_attribs; i++) {
      const uint attr = flat->color_attribs[i];
      memcpy(dst->data[attr], src->data[attr], sizeof(src->data[0]));
   }
}


/**
 * Flatshade tri.  Required for clipping and when unfilled tris are
 * active, otherwise handled by hardware.
 */
static void flatshade_tri( struct draw_stage *stage,
			   struct prim_header *header )
{
   struct prim_header tmp;

   tmp.det = header->det;
   tmp.edgeflags = header->edgeflags;
   tmp.v[0] = dup_vert(stage, header->v[0], 0);
   tmp.v[1] = dup_vert(stage, header->v[1], 1);
   tmp.v[2] = header->v[2];

   copy_colors(stage, tmp.v[0], tmp.v[2]);
   copy_colors(stage, tmp.v[1], tmp.v[2]);
   
   stage->next->tri( stage->next, &tmp );
}


/**
 * Flatshade line.  Required for clipping.
 */
static void flatshade_line( struct draw_stage *stage,
			    struct prim_header *header )
{
   struct prim_header tmp;

   tmp.v[0] = dup_vert(stage, header->v[0], 0);
   tmp.v[1] = header->v[1];

   copy_colors(stage, tmp.v[0], tmp.v[1]);
   
   stage->next->line( stage->next, &tmp );
}


static void flatshade_point( struct draw_stage *stage,
                             struct prim_header *header )
{
   stage->next->point( stage->next, header );
}


static void flatshade_end( struct draw_stage *stage )
{
   stage->next->end( stage->next );
}


static void flatshade_reset_stipple_counter( struct draw_stage *stage )
{
   stage->next->reset_stipple_counter( stage->next );
}


static void flatshade_destroy( struct draw_stage *stage )
{
   draw_free_tmps( stage );
   FREE( stage );
}


/**
 * Create flatshading drawing stage.
 */
struct draw_stage *draw_flatshade_stage( struct draw_context *draw )
{
   struct flat_stage *flatshade = CALLOC_STRUCT(flat_stage);

   draw_alloc_tmps( &flatshade->stage, 2 );

   flatshade->stage.draw = draw;
   flatshade->stage.next = NULL;
   flatshade->stage.begin = flatshade_begin;
   flatshade->stage.point = flatshade_point;
   flatshade->stage.line = flatshade_line;
   flatshade->stage.tri = flatshade_tri;
   flatshade->stage.end = flatshade_end;
   flatshade->stage.reset_stipple_counter = flatshade_reset_stipple_counter;
   flatshade->stage.destroy = flatshade_destroy;

   return &flatshade->stage;
}