/**

 * $Id$

 *

 * 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 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].maxz = MAX3( 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].maxz = MAX3( 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].maxz = MAX3( 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].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++;

                    }

                }

            }

        }

    }

    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 );

        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 );

    }

}