8 * create a bh_system with functions filled out for expand, centroid, and swap.
9 * optionally include item_debug and cast_ray functions if needed, otherwise,
12 * create a bh_tree struct with:
13 * user: a pointer back the base of the data you are ordering
14 * system: the system we created above which will deal with the data
16 * call bh_create( bh_tree *bh, u32 item_count, u32 item_size )
19 typedef struct bh_node bh_node
;
20 typedef struct bh_tree bh_tree
;
21 typedef struct bh_system bh_system
;
27 /* if il is 0, this is a leaf */
29 union{ u32 ir
, start
; };
43 void (*expand_bound
)( void *user
, boxf bound
, u32 item_index
);
44 float (*item_centroid
)( void *user
, u32 item_index
, int axis
);
45 void (*item_swap
)( void *user
, u32 ia
, u32 ib
);
50 * item_debug - draw this item quickly usually with lines
51 * cast_ray - shoot a ray against the object, if this is not set,
52 * raycasts will simply return the hit on the bvh node
55 void (*item_debug
)( void *user
, u32 item_index
);
56 int (*cast_ray
)( void *user
, v3f co
, v3f dir
, ray_hit
*hit
);
59 static void bh_update_bounds( bh_tree
*bh
, u32 inode
)
61 bh_node
*node
= &bh
->nodes
[ inode
];
63 box_init_inf( node
->bbx
);
64 for( u32 i
=0; i
<node
->count
; i
++ )
66 u32 idx
= node
->start
+i
;
67 bh
->system
->expand_bound( bh
->user
, node
->bbx
, idx
);
71 static void bh_subdivide( bh_tree
*bh
, u32 inode
)
73 bh_node
*node
= &bh
->nodes
[ inode
];
76 v3_sub( node
->bbx
[1], node
->bbx
[0], extent
);
79 if( extent
[1] > extent
[0] ) axis
= 1;
80 if( extent
[2] > extent
[axis
] ) axis
= 2;
82 float split
= node
->bbx
[0][axis
] + extent
[axis
]*0.5f
;
85 for( u32 t
=0; t
<node
->count
; t
++ )
87 u32 idx
= node
->start
+t
;
88 avg
+= bh
->system
->item_centroid( bh
->user
, idx
, axis
);
90 avg
/= (float)node
->count
;
95 j
= i
+ node
->count
-1;
99 if( bh
->system
->item_centroid( bh
->user
, i
, axis
) < split
)
103 bh
->system
->item_swap( bh
->user
, i
, j
);
108 u32 left_count
= i
- node
->start
;
109 if( left_count
== 0 || left_count
== node
->count
) return;
111 u32 il
= bh
->node_count
++,
112 ir
= bh
->node_count
++;
114 bh_node
*lnode
= &bh
->nodes
[il
],
115 *rnode
= &bh
->nodes
[ir
];
117 lnode
->start
= node
->start
;
118 lnode
->count
= left_count
;
120 rnode
->count
= node
->count
- left_count
;
126 /* TODO: Implement max depth, or stack */
127 bh_update_bounds( bh
, il
);
128 bh_update_bounds( bh
, ir
);
129 bh_subdivide( bh
, il
);
130 bh_subdivide( bh
, ir
);
133 static void bh_create( bh_tree
*bh
, bh_system
*sys
, u32 item_count
)
136 bh
->nodes
= malloc( sys
->item_size
* (item_count
*2-1) );
138 bh_node
*root
= &bh
->nodes
[0];
143 root
->count
= item_count
;
146 bh_update_bounds( bh
, 0 );
147 bh_subdivide( bh
, 0 );
149 bh
->nodes
= realloc( bh
->nodes
, sys
->item_size
* bh
->node_count
);
150 vg_success( "BVH done, size: %u/%u\n", bh
->node_count
, (item_count
*2-1) );
153 static void bh_debug_node( bh_tree
*bh
, u32 inode
, v3f pos
, u32 colour
)
155 bh_node
*node
= &bh
->nodes
[ inode
];
157 if( (pos
[0] >= node
->bbx
[0][0] && pos
[0] <= node
->bbx
[1][0]) &&
158 (pos
[2] >= node
->bbx
[0][2] && pos
[2] <= node
->bbx
[1][2]) )
162 vg_line_boxf( node
->bbx
, colour
);
164 bh_debug_node( bh
, node
->il
, pos
, colour
);
165 bh_debug_node( bh
, node
->ir
, pos
, colour
);
169 vg_line_boxf( node
->bbx
, 0xff00ff00 );
171 if( bh
->system
->item_debug
)
173 for( u32 i
=0; i
<node
->count
; i
++ )
175 u32 idx
= node
->start
+i
;
176 bh
->system
->item_debug( bh
->user
, idx
);
183 static int bh_ray( bh_tree
*bh
, u32 inode
, v3f co
, v3f dir
, ray_hit
*hit
)
190 stack
[1] = bh
->nodes
[0].il
;
191 stack
[2] = bh
->nodes
[0].ir
;
195 bh_node
*inode
= &bh
->nodes
[ stack
[depth
] ];
196 if( ray_aabb( inode
->bbx
, co
, dir
, hit
->dist
) )
200 for( u32 i
=0; i
<inode
->count
; i
++ )
202 u32 idx
= inode
->start
+i
;
204 if( bh
->system
->cast_ray
)
205 count
+= bh
->system
->cast_ray( bh
->user
, co
, dir
, hit
);
214 if( depth
+1 >= vg_list_size(stack
) )
216 vg_error( "Maximum stack reached!\n" );
220 stack
[depth
] = inode
->il
;
221 stack
[depth
+1] = inode
->ir
;
234 static int bh_select( bh_tree
*bh
, boxf box
, u32
*buffer
, int len
)
241 stack
[1] = bh
->nodes
[0].il
;
242 stack
[2] = bh
->nodes
[0].ir
;
246 bh_node
*inode
= &bh
->nodes
[ stack
[depth
] ];
247 if( box_overlap( inode
->bbx
, box
) )
251 if( count
+ inode
->count
>= len
)
253 vg_error( "Maximum buffer reached!\n" );
257 for( u32 i
=0; i
<inode
->count
; i
++ )
258 buffer
[ count
++ ] = inode
->start
+i
;
264 if( depth
+1 >= vg_list_size(stack
) )
266 vg_error( "Maximum stack reached!\n" );
270 stack
[depth
] = inode
->il
;
271 stack
[depth
+1] = inode
->ir
;