/*
 * Mesa 3-D graphics library
 * Version:  6.5
 *
 * Copyright (C) 1999-2005  Brian Paul   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, sublicense,
 * 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 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL 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 "glheader.h"
#include "g_context.h"
#include "g_headers.h"
#include "g_tile.h"

struct exec_machine {
   const struct setup_coefficient *coef;

   GLfloat attr[FRAG_ATTRIB_MAX][4][QUAD_SIZE];
};


/**
 * Compute quad's attributes values, as constants (GL_FLAT shading).
 */
static INLINE void cinterp( struct exec_machine *exec,
			    GLuint attrib,
			    GLuint i )
{
   GLuint j;

   for (j = 0; j < QUAD_SIZE; j++) {
      exec->attr[attrib][i][j] = exec->coef[attrib].a0[i];
   }
}


/**
 * Compute quad's attribute values by linear interpolation.
 *
 * Push into the fp:
 * 
 *   INPUT[attr] = MAD COEF_A0[attr], COEF_DADX[attr], INPUT_WPOS.xxxx
 *   INPUT[attr] = MAD INPUT[attr],   COEF_DADY[attr], INPUT_WPOS.yyyy
 */
static INLINE void linterp( struct exec_machine *exec,
			    GLuint attrib,
			    GLuint i )
{
   GLuint j;

   for (j = 0; j < QUAD_SIZE; j++) {
      const GLfloat x = exec->attr[FRAG_ATTRIB_WPOS][0][j];
      const GLfloat y = exec->attr[FRAG_ATTRIB_WPOS][1][j];
      exec->attr[attrib][i][j] = (exec->coef[attrib].a0[i] +
				  exec->coef[attrib].dadx[i] * x + 
				  exec->coef[attrib].dady[i] * y);
   }
}


/**
 * Compute quad's attribute values by linear interpolation with
 * perspective correction.
 *
 * Push into the fp:
 * 
 *   INPUT[attr] = MAD COEF_A0[attr], COEF_DADX[attr], INPUT_WPOS.xxxx
 *   INPUT[attr] = MAD INPUT[attr],   COEF_DADY[attr], INPUT_WPOS.yyyy
 *   INPUT[attr] = MUL INPUT[attr],   INPUT_WPOS.wwww
 *
 * (Or should that be 1/w ???)
 */
static INLINE void pinterp( struct exec_machine *exec,
			    GLuint attrib,
			    GLuint i )
{
   GLuint j;

   for (j = 0; j < QUAD_SIZE; j++) {
      const GLfloat x = exec->attr[FRAG_ATTRIB_WPOS][0][j];
      const GLfloat y = exec->attr[FRAG_ATTRIB_WPOS][1][j];
      const GLfloat invW = exec->attr[FRAG_ATTRIB_WPOS][3][j];
      exec->attr[attrib][i][j] = ((exec->coef[attrib].a0[i] +
				   exec->coef[attrib].dadx[i] * x + 
				   exec->coef[attrib].dady[i] * y) * invW);
   }
}



/* This should be done by the fragment shader execution unit (code
 * generated from the decl instructions).  Do it here for now.
 */
void quad_shade( struct generic_context *generic,
		 struct quad_header *quad )
{
   struct exec_machine exec;
   GLfloat fx = quad->x0;
   GLfloat fy = quad->y0;
   GLuint i, j;

   exec.coef = quad->coef;

   /* Position:
    */
   exec.attr[FRAG_ATTRIB_WPOS][0][0] = fx;
   exec.attr[FRAG_ATTRIB_WPOS][0][1] = fx + 1.0;
   exec.attr[FRAG_ATTRIB_WPOS][0][2] = fx;
   exec.attr[FRAG_ATTRIB_WPOS][0][3] = fx + 1.0;

   exec.attr[FRAG_ATTRIB_WPOS][1][0] = fy;
   exec.attr[FRAG_ATTRIB_WPOS][1][1] = fy;
   exec.attr[FRAG_ATTRIB_WPOS][1][2] = fy + 1.0;
   exec.attr[FRAG_ATTRIB_WPOS][1][3] = fy + 1.0;

   /* Z and W are done by linear interpolation:
    * XXX we'll probably have to use integers for Z
    */
   if (generic->need_z) {
      linterp(&exec, 0, 2);
   }

   if (generic->need_w) {
      linterp(&exec, 0, 3);
//      invert(&exec, 0, 3);
   }

   /* Interpolate all the remaining attributes.  This will get pushed
    * into the fragment program's responsibilities at some point.
    */
   for (i = 1; i < quad->nr_attrs; i++) {
#if 1
      for (j = 0; j < NUM_CHANNELS; j++)
	 linterp(&exec, i, j);
#else
      switch (quad->interp[i]) {
      case INTERP_CONSTANT:
	 for (j = 0; j < NUM_CHANNELS; j++)
	    cinterp(&exec, i, j);
	 break;
      
      case INTERP_LINEAR:
	 for (j = 0; j < NUM_CHANNELS; j++)
	    linterp(&exec, i, j);
	 break;

      case INTERP_PERSPECTIVE:
	 for (j = 0; j < NUM_CHANNELS; j++)
	    pinterp(&exec, i, j);
	 break;
      }
#endif
   }

#if 0
   generic->run_fs( tri->fp, quad, &tri->outputs );
#else
   {
      GLuint attr = generic->fp_attr_to_slot[FRAG_ATTRIB_COL0];
      assert(attr);

      memcpy(quad->outputs.color, 
	     exec.attr[attr], 
	     sizeof(quad->outputs.color));
   }
#endif


   if (quad->mask)
      quad_output( generic, quad );
}