src/gallium/drivers/softpipe/sp_quad_fs.c

/**************************************************************************
 * 
 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
 * All Rights Reserved.
 * Copyright 2008 VMware, Inc.  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.
 * 
 **************************************************************************/

/* Vertices are just an array of floats, with all the attributes
 * packed.  We currently assume a layout like:
 *
 * attr[0][0..3] - window position
 * attr[1..n][0..3] - remaining attributes.
 *
 * Attributes are assumed to be 4 floats wide but are packed so that
 * all the enabled attributes run contiguously.
 */

#include "util/u_math.h"
#include "util/u_memory.h"
#include "pipe/p_defines.h"
#include "pipe/p_shader_tokens.h"

#include "sp_context.h"
#include "sp_state.h"
#include "sp_quad.h"
#include "sp_quad_pipe.h"


struct quad_shade_stage
{
   struct quad_stage stage;  /**< base class */

   /* no other fields at this time */
};


/** cast wrapper */
static INLINE struct quad_shade_stage *
quad_shade_stage(struct quad_stage *qs)
{
   return (struct quad_shade_stage *) qs;
}


/**
 * Execute fragment shader for the four fragments in the quad.
 * \return TRUE if quad is alive, FALSE if all four pixels are killed
 */
static INLINE boolean
shade_quad(struct quad_stage *qs, struct quad_header *quad)
{
   struct softpipe_context *softpipe = qs->softpipe;
   struct tgsi_exec_machine *machine = softpipe->fs_machine;

   /* run shader */
   machine->flatshade_color = softpipe->rasterizer->flatshade ? TRUE : FALSE;
   return softpipe->fs_variant->run( softpipe->fs_variant, machine, quad );
}



static void
coverage_quad(struct quad_stage *qs, struct quad_header *quad)
{
   struct softpipe_context *softpipe = qs->softpipe;
   uint cbuf;

   /* loop over colorbuffer outputs */
   for (cbuf = 0; cbuf < softpipe->framebuffer.nr_cbufs; cbuf++) {
      float (*quadColor)[4] = quad->output.color[cbuf];
      unsigned j;
      for (j = 0; j < TGSI_QUAD_SIZE; j++) {
         assert(quad->input.coverage[j] >= 0.0);
         assert(quad->input.coverage[j] <= 1.0);
         quadColor[3][j] *= quad->input.coverage[j];
      }
   }
}


/**
 * Shade/write an array of quads
 * Called via quad_stage::run()
 */
static void
shade_quads(struct quad_stage *qs, 
            struct quad_header *quads[],
            unsigned nr)
{
   struct softpipe_context *softpipe = qs->softpipe;
   struct tgsi_exec_machine *machine = softpipe->fs_machine;
   unsigned i, nr_quads = 0;

   tgsi_exec_set_constant_buffers(machine, PIPE_MAX_CONSTANT_BUFFERS,
                         softpipe->mapped_constants[PIPE_SHADER_FRAGMENT],
                         softpipe->const_buffer_size[PIPE_SHADER_FRAGMENT]);

   machine->InterpCoefs = quads[0]->coef;

   for (i = 0; i < nr; i++) {
      /* Only omit this quad from the output list if all the fragments
       * are killed _AND_ it's not the first quad in the list.
       * The first quad is special in the (optimized) depth-testing code:
       * the quads' Z coordinates are step-wise interpolated with respect
       * to the first quad in the list.
       * For multi-pass algorithms we need to produce exactly the same
       * Z values in each pass.  If interpolation starts with different quads
       * we can get different Z values for the same (x,y).
       */
      if (!shade_quad(qs, quads[i]) && i > 0)
         continue; /* quad totally culled/killed */

      if (/*do_coverage*/ 0)
         coverage_quad( qs, quads[i] );

      quads[nr_quads++] = quads[i];
   }
   
   if (nr_quads)
      qs->next->run(qs->next, quads, nr_quads);
}
   

/**
 * Per-primitive (or per-begin?) setup
 */
static void
shade_begin(struct quad_stage *qs)
{
   qs->next->begin(qs->next);
}


static void
shade_destroy(struct quad_stage *qs)
{
   FREE( qs );
}


struct quad_stage *
sp_quad_shade_stage( struct softpipe_context *softpipe )
{
   struct quad_shade_stage *qss = CALLOC_STRUCT(quad_shade_stage);
   if (!qss)
      goto fail;

   qss->stage.softpipe = softpipe;
   qss->stage.begin = shade_begin;
   qss->stage.run = shade_quads;
   qss->stage.destroy = shade_destroy;

   return &qss->stage;

fail:
   FREE(qss);
   return NULL;
}