text: /**************************************************************************
   * 
   * 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 < 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)
  {
     struct softpipe_context *softpipe = qs->softpipe;
  
     softpipe->fs_variant->prepare( softpipe->fs_variant, 
                                    softpipe->fs_machine,
                                    (struct tgsi_sampler **)
                                    softpipe->tgsi.frag_samplers_list );
  
     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;
  }
  