/**

  * $Id$

  *

  * 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"

 extern char *video_base;

 #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 minz;

 };

 #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 minz 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 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 {

 	    uint32_t poly_addr = entry & 0x000FFFFF;

 	    int is_modified = entry & 0x01000000;

 	    int vertex_length = (entry >> 21) & 0x07;

 	    int context_length = 3;

 	    if( is_modified && pvr2_scene.full_shadow ) {

 		context_length = 5;

 		vertex_length *= 2 ;

 	    }

 	    vertex_length += 3;

 	    if( (entry & 0xE0000000) == 0x80000000 ) {

 		/* Triangle(s) */

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

 		int polygon_length = 3 * vertex_length + context_length;

 		int i;

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

 		    struct polygon_struct *poly = pvr2_scene.buf_to_poly_map[poly_addr];

 		    triangles[count].poly = poly;

 		    triangles[count].triangle_num = 0;

 		    triangles[count].minz = MIN3( pvr2_scene.vertex_array[poly->vertex_index].z,

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

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

 		    poly_addr += polygon_length;

 		    count++;

 		}

 	    } else if( (entry & 0xE0000000) == 0xA0000000 ) {

 		/* Quad(s) */

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

 		int polygon_length = 4 * vertex_length + context_length;

 		int i;

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

 		    struct polygon_struct *poly = pvr2_scene.buf_to_poly_map[poly_addr];

 		    triangles[count].poly = poly;

 		    triangles[count].triangle_num = 0;

 		    triangles[count].minz = MIN3( pvr2_scene.vertex_array[poly->vertex_index].z,

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

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

 		    count++;

 		    triangles[count].poly = poly;

 		    triangles[count].triangle_num = 1;

 		    triangles[count].minz = MIN3( pvr2_scene.vertex_array[poly->vertex_index+1].z,

 						  pvr2_scene.vertex_array[poly->vertex_index+2].z,

 						  pvr2_scene.vertex_array[poly->vertex_index+3].z );

 		    count++;

 		    poly_addr += polygon_length;

 		}

 	    } else {

 		/* Polygon */

 		int i;

 		struct polygon_struct *poly = pvr2_scene.buf_to_poly_map[poly_addr];

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

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

 			triangles[count].poly = poly;

 			triangles[count].triangle_num = i;

 			triangles[count].minz = MIN3( 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++;

 		    }

 		}

 	    }

 	}

     }

     return 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 );

 	glEnable(GL_DEPTH_TEST);

 	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->minz - tri1->minz;

 }

 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;

 	sort_extract_triangles(tile_entry, triangles);

 	sort_triangles( triangles, num_triangles );

 	sort_render_triangles(triangles, num_triangles, render_mode);

 	glCullFace(GL_BACK);

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

     }

 }