/**

  * $Id$

  *

  * PVR2 renderer routines for depth sorted polygons

  *

  * Copyright (c) 2005 Nathan Keynes.

  *

  * This program is free software; you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation; either version 2 of the License, or

  * (at your option) any later version.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  */

 #include <sys/time.h>

 #include <string.h>

 #include <assert.h>

 #include "pvr2/pvr2.h"

 #include "pvr2/scene.h"

 #include "asic.h"

 #define MIN3( a,b,c ) ((a) < (b) ? ( (a) < (c) ? (a) : (c) ) : ((b) < (c) ? (b) : (c)) )

 #define MAX3( a,b,c ) ((a) > (b) ? ( (a) > (c) ? (a) : (c) ) : ((b) > (c) ? (b) : (c)) )

 struct sort_triangle {

     struct polygon_struct *poly;

     int triangle_num; // triangle number in the poly, from 0

     float maxz;

 };

 #define SENTINEL 0xDEADBEEF

 /**

  * Count the number of triangles in the list starting at the given 

  * pvr memory address.

  */

 int sort_count_triangles( pvraddr_t tile_entry ) {

     uint32_t *tile_list = (uint32_t *)(video_base+tile_entry);

     int count = 0;

     while(1) {

         uint32_t entry = *tile_list++;

         if( entry >> 28 == 0x0F ) {

             break;

         } else if( entry >> 28 == 0x0E ) {

             tile_list = (uint32_t *)(video_base+(entry&0x007FFFFF));

         } else if( entry >> 29 == 0x04 ) { /* Triangle array */

             count += ((entry >> 25) & 0x0F)+1;

         } else if( entry >> 29 == 0x05 ) { /* Quad array */

             count += ((((entry >> 25) & 0x0F)+1)<<1);

         } else { /* Polygon */

             int i;

             for( i=0; i<6; i++ ) {

                 if( entry & (0x40000000>>i) ) {

                     count++;

                 }

             }

         }

     }

     return count;

 }

 /**

  * Extract a triangle list from the tile (basically indexes into the polygon list, plus

  * computing maxz while we go through it

  */

 int sort_extract_triangles( pvraddr_t tile_entry, struct sort_triangle *triangles )

 {

     uint32_t *tile_list = (uint32_t *)(video_base+tile_entry);

     int strip_count;

     struct polygon_struct *poly;

     int count = 0, i;

     while(1) {

         uint32_t entry = *tile_list++;

         switch( entry >> 28 ) {

         case 0x0F:

             return count; // End-of-list

         case 0x0E:

             tile_list = (uint32_t *)(video_base + (entry&0x007FFFFF));

             break;

         case 0x08: case 0x09: case 0x0A: case 0x0B:

             strip_count = ((entry >> 25) & 0x0F)+1;

             poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

             while( strip_count > 0 ) {

                 assert( poly != NULL );

                 for( i=0; i<poly->vertex_count-2; i++ ) { 

                     triangles[count].poly = poly;

                     triangles[count].triangle_num = i;

                     triangles[count].maxz = MAX3( pvr2_scene.vertex_array[poly->vertex_index+i].z,

                             pvr2_scene.vertex_array[poly->vertex_index+i+1].z,

                             pvr2_scene.vertex_array[poly->vertex_index+i+2].z );

                     count++;

                 }

                 poly = poly->next;

                 strip_count--;

             }

             break;

         default:

             if( entry & 0x7E000000 ) {

                 poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

                 for( i=0; i<6; i++ ) {

                     if( entry & (0x40000000>>i) ) {

                         triangles[count].poly = poly;

                         triangles[count].triangle_num = i;

                         triangles[count].maxz = MAX3( pvr2_scene.vertex_array[poly->vertex_index+i].z,

                                 pvr2_scene.vertex_array[poly->vertex_index+i+1].z,

                                 pvr2_scene.vertex_array[poly->vertex_index+i+2].z );

                         count++;

                     }

                 }

             }

         }

     }       

 }

 void sort_render_triangles( struct sort_triangle *triangles, int num_triangles,

                             int render_mode )

 {

     int i;

     for( i=0; i<num_triangles; i++ ) {

         struct polygon_struct *poly = triangles[i].poly;

         if( poly->tex_id != -1 ) {

             glBindTexture(GL_TEXTURE_2D, poly->tex_id);

         }

         render_set_context( poly->context, RENDER_NORMAL );

         glDepthMask(GL_FALSE);

         glDepthFunc(GL_GEQUAL);

         /* Fix cull direction */

         if( triangles[i].triangle_num & 1 ) {

             glCullFace(GL_FRONT);

         } else {

             glCullFace(GL_BACK);

         }

         glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index + triangles[i].triangle_num, 3 );

     }

 }

 int compare_triangles( const void *a, const void *b ) 

 {

     const struct sort_triangle *tri1 = a;

     const struct sort_triangle *tri2 = b;

     return tri2->maxz - tri1->maxz;

 }

 void sort_triangles( struct sort_triangle *triangles, int num_triangles )

 {

     qsort( triangles, num_triangles, sizeof(struct sort_triangle), compare_triangles );

 } 

 void render_autosort_tile( pvraddr_t tile_entry, int render_mode ) 

 {

     int num_triangles = sort_count_triangles(tile_entry);

     if( num_triangles == 0 ) {

         return; /* nothing to do */

     } else if( num_triangles == 1 ) { /* Triangle can hardly overlap with itself */

         gl_render_tilelist(tile_entry);

     } else { /* Ooh boy here we go... */

         struct sort_triangle triangles[num_triangles+1];

         // Reserve space for num_triangles / 2 * 4 vertexes (maximum possible number of

         // quad vertices)

         triangles[num_triangles].poly = (void *)SENTINEL;

         int extracted_triangles = sort_extract_triangles(tile_entry, triangles);

         assert( extracted_triangles == num_triangles );

         sort_triangles( triangles, num_triangles );

         sort_render_triangles(triangles, num_triangles, render_mode);

         glCullFace(GL_BACK);

         assert( triangles[num_triangles].poly == (void *)SENTINEL );

     }

 }