/**

 * $Id$

 *

 * 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)) )

#define EPSILON 0.0001

struct sort_triangle {

    struct polygon_struct *poly;

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

    /* plane equation */

    float mx, my, mz, d;

    float bounds[6]; /* x1,x2,y1,y2,z1,z2 */

};

#define SENTINEL 0xDEADBEEF

/**

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

 * pvr memory address.

 */

static 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;

}

static void sort_add_triangle( struct sort_triangle *triangle, struct polygon_struct *poly, int index )

{

    struct vertex_struct *vertexes = &pvr2_scene.vertex_array[poly->vertex_index+index];

    triangle->poly = poly;

    triangle->triangle_num = index;

    /* Compute triangle bounding-box */

    triangle->bounds[0] = MIN3(vertexes[0].x,vertexes[1].x,vertexes[2].x);

    triangle->bounds[1] = MAX3(vertexes[0].x,vertexes[1].x,vertexes[2].x);

    triangle->bounds[2] = MIN3(vertexes[0].y,vertexes[1].y,vertexes[2].y);

    triangle->bounds[3] = MAX3(vertexes[0].y,vertexes[1].y,vertexes[2].y);

    triangle->bounds[4] = MIN3(vertexes[0].z,vertexes[1].z,vertexes[2].z);

    triangle->bounds[5] = MAX3(vertexes[0].z,vertexes[1].z,vertexes[2].z);

    /* Compute plane equation */

    float sx = vertexes[1].x - vertexes[0].x;

    float sy = vertexes[1].y - vertexes[0].y;

    float sz = vertexes[1].z - vertexes[0].z;

    float tx = vertexes[2].x - vertexes[0].x;

    float ty = vertexes[2].y - vertexes[0].y;

    float tz = vertexes[2].z - vertexes[0].z;

    triangle->mx = sy*tz - sz*ty;

    triangle->my = sz*tx - sx*tz;

    triangle->mz = sx*ty - sy*tx;

    triangle->d = -vertexes[0].x*triangle->mx - 

                  vertexes[0].y*triangle->my - 

                  vertexes[0].z*triangle->mz;

}

/**

 * 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++ ) {

                    sort_add_triangle( &triangles[count], poly, i );

                    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) ) {

                        sort_add_triangle( &triangles[count], poly, i );

                        count++;

                    }

                }

            }

        }

    }       

}

void sort_render_triangles( struct sort_triangle **triangles, int num_triangles )

{

    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, GL_GEQUAL );

        glDepthMask(GL_FALSE);

        /* 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 );

    }

}

static int sort_triangle_compare( const void *a, const void *b ) 

{

    const struct sort_triangle *tri1 = a;

    const struct sort_triangle *tri2 = b;

    if( tri1->bounds[5] <= tri2->bounds[4] ) 

        return 1; /* tri1 is entirely under tri2 */

    else if( tri2->bounds[5] <= tri1->bounds[4] )

        return -1;  /* tri2 is entirely under tri1 */

    else if( tri1->bounds[1] <= tri2->bounds[0] ||

             tri2->bounds[1] <= tri1->bounds[0] ||

             tri1->bounds[3] <= tri2->bounds[2] ||

             tri2->bounds[3] <= tri1->bounds[2] )

        return 0; /* tri1 and tri2 don't actually overlap at all */

    else { 

        struct vertex_struct *tri1v = &pvr2_scene.vertex_array[tri1->poly->vertex_index + tri1->triangle_num];

        struct vertex_struct *tri2v = &pvr2_scene.vertex_array[tri2->poly->vertex_index + tri2->triangle_num];

        float v[3];

        int i;

        for( i=0; i<3; i++ ) {

            v[i] = tri1->mx * tri2v[i].x + tri1->my * tri2v[i].y + tri1->mz * tri2v[i].z + tri1->d;

            if( v[i] > -EPSILON && v[i] < EPSILON ) v[i] = 0;

        }

        if( v[0] == 0 && v[1] == 0 && v[2] == 0 ) {

            return 0; /* coplanar */

        }

        if( (v[0] >=0 && v[1] >= 0 && v[2] >= 0) ||

            (v[0] <= 0 && v[1] <= 0 && v[2] <= 0) ) {

            /* Tri is on one side of the plane. Pick an arbitrary point to determine which side */

            float t1z = -(tri1->mx * tri2v[0].x + tri1->my * tri2v[0].y + tri1->d) / tri1->mz;

            return tri2v[0].z - t1z;

        }

        /* If the above test failed, then tri2 intersects tri1's plane. This

         * doesn't necessarily mean the triangles intersect (although they may).

         * For now just return 0, and come back to this later as it's a fairly

         * uncommon case in practice. 

         */

        return 0;

    }

}

/**

 * This is pretty much a standard merge sort (Unfortunately can't depend on

 * the system to provide one. Note we can't use quicksort here - the sort

 * must be stable to preserve the order of coplanar triangles.

 */

static void sort_triangles( struct sort_triangle **triangles, int num_triangles, struct sort_triangle **out )

{

    if( num_triangles > 2 ) {

        int l = num_triangles>>1, r=num_triangles-l, i=0,j=0;

        struct sort_triangle *left[l];

        struct sort_triangle *right[r];

        sort_triangles( triangles, l, left );

        sort_triangles( triangles+l, r, right );

        /* Merge */

        while(1) {

            if( sort_triangle_compare(left[i], right[j]) <= 0 ) {

                *out++ = left[i++];

                if( i == l ) {

                    memcpy( out, &right[j], (r-j)*sizeof(struct sort_triangle *) );        

                    break;

                }

            } else {

                *out++ = right[j++];

                if( j == r ) {

                    memcpy( out, &left[i], (l-i)*sizeof(struct sort_triangle *) );

                    break;

                }

            }

        }

    } else if( num_triangles == 2 ) {

        if( sort_triangle_compare(triangles[0], triangles[1]) <= 0 ) {

            out[0] = triangles[0];

            out[1] = triangles[1];

        } else {

            struct sort_triangle *tmp = triangles[0];

            out[0] = triangles[1];

            out[1] = tmp;

        }

    } else {

        out[0] = triangles[0];

    }

} 

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, GL_GEQUAL);

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

        int i;

        struct sort_triangle triangles[num_triangles+1];

        struct sort_triangle *triangle_order[num_triangles+1];

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

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

            triangle_order[i] = &triangles[i];

        }

        int extracted_triangles = sort_extract_triangles(tile_entry, triangles);

        assert( extracted_triangles == num_triangles );

        sort_triangles( triangle_order, num_triangles, triangle_order );

        sort_render_triangles(triangle_order, num_triangles);

        glCullFace(GL_BACK);

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

    }

}