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_*prims

_*prims is a linked list which stores pointers to the primitives. The _*prims linked list is manipulated during the BSP tree generation to allow the tree to point to primitives.

The custom block definitions in the code are:

  • bsp._*prims.__init_non_dynamic__
  • _**prim = bsp._*prims.insert_after
  • bsp._*prims.randomize_order
  • _tmp, _tmp2 = bsp._*prims.pop
  • bsp._*prims.swap
  • bsp._*prims.sanity_check

Custom Block Descriptions#

Each custom block definition in the _*prims page of the Binary Space Partitioning documentation is described in detail in this section.

bsp._*prims.__init_non_dynamic__#


define bsp._*prims.__init_non_dynamic__

initializes the _*prims linked list with non-dynamic primitives from the primitives list.

  1. Starting from the first element in the primitives list, it iterates over the list, skipping elements belonging to dynamic GameObjects.
  2. For each non-dynamic primitive, it adds an entry in the _*prims list containing the primitive index, two pointers to form a doubly linked list, and the side ("FRONT" or "BACK") of the primitive.
    1. If a primitive has a non-zero material, an entry for the "BACK" side of the primitive is also added.
  3. The second element and the last element of the _*prims list are set to "null", and the tail pointer is set to the second-last element of the list.

_*prim = bsp._*prims.insert_after#


define _**prim = bsp._*prims.insert_after \( (*prim) (*elem) (*mem_loc) (Orientation) \)

Inserts a new primitive *prim after a given element *elem in the _*prims list. optionally can specify a memory location *mem_loc for the data to go.

  1. if the _*prims list empty, appends the data at the end of the _*prims list and returns.
  2. If *mem_loc is None:
    1. Add the _*prim and it's Orientation as a new linked list node at the end of the list.
  3. else:
    1. we replace the data slot at *mem_loc with the _*prim and it's Orientation
  4. set the correct links for the linked list such that the new node in the linked list is inserted between *elem and *elems next item.

bsp._*prims.randomize_order#


define bsp._*prims.randomize_order \( (*left) (*right) \)

The bsp._*prims.randomize_order custom block randomizes the order of the primitives in the _*prims list between the left and right indices. It iterates over the primitives, starting from the left index and going up to the right index, and swaps each primitive with another random primitive in the _*prims list.

_tmp, _tmp2 = bsp._*prims.pop#


define _tmp, _tmp2 = bsp._*prims.pop \( (*elem) \)

The _tmp, _tmp2 = bsp._*prims.pop custom block removes a primitive from the _*prims list. The previous and next elements' pointers are updated to skip over the removed element. If the removed element is the last element in the list, the tail pointer is updated. The primitive and its orientation are stored, and the removed element's entries in the _*prims list are cleared.

bsp._*prims.swap#


define bsp._*prims.swap \( *a (*a) *b (*b) \)

The bsp._*prims.swap custom block swaps two primitives in the _*prims list. The primitives and their orientations are swapped using a temporary variable.

bsp._*prims.sanity_check#


define bsp._*prims.sanity_check \( (*left) (*right) \)

The bsp._*prims.sanity_check custom block checks the consistency of the _*prims list between the left and right indices. It iterates over the primitives and checks that each primitive index is a multiple of the size of a primitive. It also checks that the previous and next element pointers for each primitive point to the correct elements. If an inconsistency is detected, a breakpoint is triggered.