OBD:OTLF: Difference between revisions

{{OBDtr| 0x08 | char[20] |00FF00| AD DE      | dead            | unused }}

{{OBDtr| 0x1C | int32   |00FFFF| 03 49 00 00 | 18691            | array size }}

{{OBDtr| 0x00 | int12-20 |FFC8C8| 00 00 00 00 | 0, 0            | bits 0-11 (12 bits) contain the number of gunk quads that intersect this leaf, bits 12-31 (20 bits) contain the index of the gunk quad list; see details below }}

{{OBDtr| 0x04 | int32hb |FFFFC8| FF FF FF FF | -1              | negative x neighbour }}

{{OBDtr| 0x08 | int32hb |C8FFC8| 01 00 00 80 | 1, high bit      | positive x neighbour }}

{{OBDtr| 0x0C | int32hb |C8FFFF| FF FF FF FF | -1              | negative y neighbour }}

{{OBDtr| 0x10 | int32hb |FFC8FF| 02 00 00 80 | 2, high bit      | positive y neighbour }}

{{OBDtr| 0x14 | int32hb |FFC800| FF FF FF FF | -1              | negative z neighbour }}

{{OBDtr| 0x18 | int32hb |C800C8| 04 00 00 80 | 4, high bit      | positive z neighbour }}

{{OBDtr| 0x1C |int9-9-9-5|C87C64| 7F FE FC 39 | 127, 127, 127, 7 | bits 0-8 (9 bits) contain the index of max x, bits 9-17 (9 bits) contain the index of max y, bits 18-26 (9 bits) contain the index of max z and bits 27-31 (5 bits) contain the index of the size of this leaf; see details below }}

{{OBDtr| 0x20 | int8-24  |B0C3D4| 00 00 00 00 | 0, 0            | bits 0-7 (8 bits) intersected BNV count, bits 8-31 (24 bits) BNV list index; see details below }}

:An octtree leaf (OTLF) stores its size and position and the gunk quads that intersect it. The first field contains an index/count pair that is used to access the first [[OBD:IDXA|IDXA]] field that is stored in the [[OBD:AKOT|AKOT]] that owns this leaf. This [[OBD:IDXA|IDXA]] contains the gunk quad numbers that intersect the leaf. In theory there can be at most 4096 gunk quads that intersect a leaf but in practice this number is much lower (max is 462). In addition the threshold limit used to build the octree seems to be 19 gunk quads per leaf. I.e., in Oni's levels, only the smallest leaves (with size 16x16x16) have more than 19 quads; larger leaves containing 20 and more quads are subdivided into "other, smaller boxes".

:If the 8192x8192x8192 environment is subdivided into 16x16x16 cubes in all three directions, the total number of leaves is 512x512x512 = 134,217,728. Theoretically the data structures allow for a densely packed level where each 16x16x16 volume has some quads inside it (theoretically up to 4096, i.e., a maximum of 549,755,813,888 quads per level). In practice, the engine imposes much more modest limitations: a maximum of 262144 quads per level (tentative, to be confirmed), and probably another limitation on the amount of polygons on-screen. Coincidentally, 262144=512x512 quads exactly correspond to a 8192x8192 floor paved (in two directions) with 16x16 quads.