======== Geometry Layout Commands ========

The geometry layout commands define how geometric shapes are drawn.  Some geo layouts are contained after the Level data blocks and some are loaded with [[super_mario_64:level_commands#17: Load ROM to Segment|Level Command 0x17]] The first byte of the geo layout command is the command type.  Unlike the level commands, there is no length byte specified in the command.  Most geo layout commands are constant length, however, some depend on the values set.

===== Drawing Layers =====

^ Layer ^ Description ^
| 00 | Unused |
| 01 | Entirely Solid (Blending disabled)|
| 02 | Decals or triangles that draw on top of geometry near the same depth (Lessened depth-range). Blending disabled. |
| 03 | Unused |
| 04 | Transparent pixels, no blending (OpenGL's equivalent is Alphatest). Allows perfect layering with other transparencies around it. |
| 05 | Blending (translucency) enabled. Layering must be handled with the order of drawn faces. |
| 06 | Blending (translucency) enabled. Layering must be handled with the order of drawn faces. This layer is always drawn behind layer 05, usually for shadows. Lessened depth-range. |

===== Geometry Layout Commands =====
==== 00: Branch and Store ====
Branches to segmented address and stores 2 return addresses. This command is not used in the ROM.

''00 00 00 00 [<color darkred>SS SS SS SS</color>]''

| <color darkred>S</color> | Segmented address to branch to |

<code c>
/* Geo Layout 0x00 Rough translation. */
// 0x8038BD80 = Pointer to current Geo layout command
// 0x8038BCB8 = Pointer to array/table to where branch return pointers are stored.
// 0x8038BD7A = Branch depth value.
*(0x8038BCB8 + (0x8038BD7A * 4)) = *0x8038BD80 + 8; // Stores the pointer to the next geo command
*0x8038BD7A += 1; // Increment branch value

*(0x8038BCB8 + (0x8038BD7A * 4)) = (*0x8038BD78 << 16) + *0x8038BD7E; // Store another address
*0x8038BD7A += 1; // Increment branch value
*0x8038BD7E = *0x8038BD7A;

0x8038BD80 = SegmentedToVirtual(0x8038BD80 + 4); // Go to the segmented address.
</code>

Length: 8

----

==== 01: Terminate Geometry Layout ====
The ending command to close.

''01 00 00 00''

Length: 4

----

==== 02: Branch Geometry Layout ====
Branches the current geo layout to another area within a RAM bank.

''02 [<color darkblue>AA</color>] 00 00 [<color darkred>SS SS SS SS</color>]''

| <color darkblue>A</color> | 0 = Jump, 1 = Jump and store return address |
| <color darkred>S</color> | Segmented address to branch to |

Length: 8

----

==== 03: Return From Branch ====
Ends the current geometry layout branch and returns to the area following the 0x02 command.

''03 00 00 00''

Length: 4

----

==== 04: Open Node ====
If you don't understand nodes, this is basically like a sub-folder.

''04 00 00 00''

Length: 4

----

==== 05: Close Node ====
Used at the end of the data within the opened node.

''05 00 00 00''

Length: 4

----

==== 06: Unused ====

----

==== 07: Unused ====

----

==== 08: Set Screen Render Area ====
Only used in geo layout of levels.

''08 00 00 [<color darkgrey>AA</color>] [<color darkred>XX XX</color>] [<color darkgreen>YY YY</color>] [<color darkblue>WW WW</color>] [<color purple>HH HH</color>]''

| <color darkgrey>A</color> | Either 00 (mario face) or 0A (all other levels) |
| <color darkred>X</color> | X position |
| <color darkgreen>Y</color> | Y position |
| <color darkblue>W</color> | Width of screen |
| <color purple>H</color> | Height of screen |

Length: C

----

==== 09: ?? ====
Only used in geo layout of levels.

''09 00 00 [<color darkred>AA</color>]''

| <color darkred>A</color> | Always 0x64 |

Length: 4

----

==== 0A: Set Camera Frustum ====
Set camera frustum properties. Only used in geo layout of levels.

''0A [<color darkgray>AA</color>] [<color darkred>BB BB</color>] [<color darkgreen>NN NN</color>] [<color darkblue>FF FF</color>] {<color purple>EE EE EE EE</color>}''

| <color darkgray>A</color> | Use ASM code defined by <color purple>E</color> |
| <color darkred>B</color> | Camera FOV (0x2D = 45) |
| <color darkgreen>N</color> | Camera Near |
| <color darkblue>F</color> | Camera Far |
| <color purple>E</color> | optional ASM function if <color darkred>A</color> is non-zero (always  8029AA3C) |

Length: 8-C (variable)

----

==== 0B: Start Geo Layout ====
Starts geometry layout with no parameters whatsoever. Seems to use a pre-set render area.

''0B 00 00 00''

Length: 4

----

==== 0C: Enable/Disable Z-Buffer ====

This command is used in level geometry layouts. Z-Buffering is disabled when rendering the skybox, and re-enabled when rendering level geometry.

''0C [<color darkgray>AA</color>] 00 00''

| <color darkgray>A</color> | 0x00 = Disable Z-buffer, 0x01 = Enable Z-buffer |

''[ 0C 01 00 00 ]'' will add the following Fast3D data to the following node:
  E7 00 00 00 00 00 00 00
  B7 00 00 00 00 00 00 01
  // Node's Fast3D commands
  E7 00 00 00 00 00 00 00
  B6 00 00 00 00 00 00 01
  
Length: 4
----

==== 0D: Set Render Range ====
Used in WF, CCM, TTM, SSL levels and some geo layouts. This command will make the following node only render in a certain distance range away from the camera.

''0D 00 00 00 [<color darkred>AA AA</color>] [<color darkgreen>BB BB</color>]''

| <color darkred>A</color> | (s16) Minimum distance value |
| <color darkgreen>B</color> | (s16) Maximum distance value |

Example from "Grassy Level Part" in Whomp's fortress:
  0049E3A8 / 0E000958 [ 20 00 07 D0 ]
  0049E3AC / 0E00095C [ 04 00 00 00 ]
  0049E3B0 / 0E000960    [ 0D 00 00 00 F8 30 1F 40 ]
  0049E3B8 / 0E000968    [ 04 00 00 00 ]
  0049E3BC / 0E00096C       [ 15 01 00 00 07 00 AB A0 ] // Real geometry (Camera is nearby)
  0049E3C4 / 0E000974       [ 15 06 00 00 07 00 AF B8 ]
  0049E3CC / 0E00097C    [ 05 00 00 00 ]
  0049E3D0 / 0E000980    [ 0D 00 00 00 1F 40 4E 20 ]
  0049E3D8 / 0E000988    [ 04 00 00 00 ]
  0049E3DC / 0E00098C       [ 15 01 00 00 07 00 AE C8 ] // Fake geometry (Camera is far away)
  0049E3E4 / 0E000994    [ 05 00 00 00 ]
  0049E3E8 / 0E000998 [ 05 00 00 00 ]
  0049E3EC / 0E00099C [ 01 00 00 00 ]


Length: 8

----

==== 0E: Switch Case ====
Loads ASM in RAM that switches between the receding display lists within the node.

''0E 00 00 [<color darkgray>NN</color>] [<color purple>AA AA AA AA</color>]''

| <color darkgray>N</color> | Number of cases/display lists, starting at 01 |
| <color purple>A</color> | ASM Function |

Length: 8

----

==== 0F: ?? ====

''0F 00 [<color darkgray>TT TT</color>] [<color darkred>XX XX</color>] [<color darkgreen>YY YY</color>] [<color darkblue>ZZ ZZ</color>] [<color red>UU UU</color>] [<color green>VV VV</color>] [<color blue>WW WW</color>] [<color purple>AA AA AA AA</color>]''

| <color darkgray>T</color> | ?? |
| <color darkred>X</color> | ?? (s16) |
| <color darkgreen>Y</color> | ?? (s16) |
| <color darkblue>Z</color> | ?? (s16) |
| <color red>U</color> | ?? (s16) |
| <color green>V</color> | ?? (s16) |
| <color blue>W</color> | ?? (s16) |
| <color purple>A</color> | ASM function. Always 80287D30 (levels) or 00 (menus) |

Length: 0x14

----

==== 10: Translate and Rotate ====
Applies translation & rotation to the following node.

''10 [<color darkgrey>AA</color>] [<color purple>BB BB</color>] [<color darkred>XX XX</color>] [<color darkgreen>YY YY</color>] [<color darkblue>ZZ ZZ</color>] [<color red>RX RX</color>] [<color green>RY RY</color>] [<color blue>RZ RZ</color>]''

| <color darkgrey>A</color> | Branching flag |
| <color purple>B</color> | Used if <color darkgrey>A</color> != 0 |
| <color darkred>X</color> | X translation offset (s16) |
| <color darkgreen>Y</color> | Y translation offset (s16) |
| <color darkblue>Z</color> | Z translation offset (s16) |
| <color red>RX</color> | X rotation (s16) |
| <color green>RY</color> | Y rotation (s16) |
| <color blue>RZ</color> | Z rotation (s16) |

Length: 0x10

----
==== 13: Load Display List ====
Loads display list with drawing layer and offsets the model on X/Y/Z axis.

''13 [<color darkgray>LL</color>] [<color darkred>XX XX</color>] [<color darkgreen>YY YY</color>] [<color darkblue>ZZ ZZ</color>] [<color purple>AA AA AA AA</color>]''

| <color darkgray>L</color> | Drawing layer |
| <color darkred>X</color> | Offset on X axis (s16) |
| <color darkgreen>Y</color> | Offset on Y axis (s16) |
| <color darkblue>Z</color> | Offset on Z axis (s16) |
| <color purple>A</color> | Segmented address with display list \\ If 0x00000000, an invisible rotation joint is created |

Length: C

----

==== 14: Billboard Model ====
Billboards the model without needing the use of 0x21 in the behavior script.

''14 00 00 00 00 00 00 00''

Length: 8

----

==== 15: Load Display List ====
Loads display list with drawing layer and no other properties.

''15 [<color darkgray>LL</color>] 00 00 [<color purple>AA AA AA AA</color>]''

| <color darkgray>L</color> | Drawing layer |
| <color purple>A</color> | Segmented address with display list |

Length: 8

----

==== 16: Start Geo Layout with Shadow ====
Used at start of the geo layout, with shadow type, solidity, and size.

''16 00 00 [<color darkred>AA</color>] 00 [<color darkgreen>BB</color>] [<color darkblue>CC CC</color>]''

| <color darkred>A</color> | Shadow type |
| <color darkgreen>B</color> | Shadow solidity (00=invisible, FF=black) |
| <color darkblue>C</color> | Shadow scale |

Length: 8

----

==== 17: Set Up Object Rendering? ====
Sets up rendering for 3D Objects? Without it, 0x24 objects placed in level do not render.

''17 00 00 00''

Length: 4

----

==== 18: Load Polygons ASM ====
Used in some original objects to point to ASM in RAM, for misc. effects such as vertex rippling. 

The 3rd and 4th bytes are parameters passed into the asm function. Argument register a1 is a pointer to the node data, and the parameters are stored as a word at offset 0x18.

''18 00 [<color purple>XX XX</color>] [<color darkred>AA AA AA AA</color>]''

| <color purple>X</color> | Parameter(s) passed into asm function. **a1->0x18** |
| <color darkred>A</color> | ASM RAM Address |

Length: 8

----

==== 19: Set Background ====
Set background image or color.

''19 00 [<color darkgrey>TT TT</color>] [<color purple>AA AA AA AA</color>]''

| <color darkgrey>T</color> | If <color purple>A</color> == 0, RGBA color, else background ID |
| <color purple>A</color> | ASM function to set the background image, always 0x802763D4 |

Length: 8

Examples:
  [ 19 00 00 00 80 27 63 D4 ] # Bob-Omb's Battlefield
  [ 19 00 00 01 80 27 63 D4 ] # Lethal Lava Land
  [ 19 00 00 02 80 27 63 D4 ] # Wet Dry World
  [ 19 00 00 03 80 27 63 D4 ] # Rainbow Ride
  [ 19 00 00 04 80 27 63 D4 ] # Cool Cool Mountain
  [ 19 00 00 05 80 27 63 D4 ] # Shifting Sand Land
  [ 19 00 00 06 80 27 63 D4 ] # Big Boo's Haunt
  [ 19 00 00 07 80 27 63 D4 ] # Bowser 1 Course
  [ 19 00 00 08 80 27 63 D4 ] # Jolly Roger Bay
  [ 19 00 00 09 80 27 63 D4 ] # Bowser 3 Course
  [ 19 00 00 01 00 00 00 00 ] # Secret Slide, pure black background

----
==== 1A: No Operation ====

Doesn't do anything, nop. This command is never used in any of the scripts.

Length: 8

----

==== 1D: Scale Model ====
Scales the receding data uniformly.

''1D [<color darkred>A</color>][<color darkgreen>B</color>] 00 00 [<color darkblue>SS SS SS SS</color>] {?? ?? ?? ??}''

| <color darkred>A</color> | If MSbit is set, load B and ?? |
| <color darkgreen>B</color> | If MSbit of <color darkred>A</color> is set, use for A2 to 8037B940 |
| <color darkblue>S</color> | Scale percentage (0x10000 = 100%) |
| ?? | optional word used if the MSbit of <color darkred>A</color> is set |

Length: 8-C (variable)

----

==== 1E: No Operation ====

Doesn't do anything, nop. This command is never used in any of the scripts.

Length: 8

----

==== 1F: No Operation ====

Doesn't do anything, nop. This command is never used in any of the scripts.

Length: 0x10

----

==== 20: Start Geo Layout with Render Area ====
Starts the geometry layout with no shadow and a render area.

''20 00 [<color darkred>AA AA</color>]''

| <color darkred>A</color> | Render distance? |

Length: 4

===== See Also =====
[[super_mario_64:level_commands]]

===== References =====
  * http://origami64.net/showthread.php?tid=9
  * http://www.smwcentral.net/?p=viewthread&t=74776
  * https://sites.google.com/site/kazemario64/geo-layout-polygon-commands
  * http://qubedstudios.rustedlogic.net/Mario64_HackingDoc1.5.txt