obj Model

• Compared with vanilla Minecraft JSON models, obj models are much more flexible for authoring. For example, uses them for blocks like the and .

  • Build an obj Model

    • First create an obj model. You can use many tools, such as , , and . Example:

      # Made in Blockbench 4.8.3
      mtllib qqqqoo.mtl
      
      o pyramid
      v 1 -2.220446049250313e-16 1
      v 1 0.9999999999999998 1.0000000000000002
      v 0 0.9999999999999998 1.0000000000000002
      v 0 -2.220446049250313e-16 1
      v 0.5 0.4999999999999999 0.5000000000000001
      vt 0.25 0.75
      vt 0.25 1
      vt 0 1
      vt 0 0.75
      vt 0 0.479471875
      vt 0.25 0.479471875
      vt 0.125 0.65625
      vt 0.1875 0.620096875
      vt 0.4375 0.620096875
      vt 0.3125 0.796875
      vt 0.265625 0.823221875
      vt 0.515625 0.823221875
      vt 0.390625 1
      vt 0.375 0.479471875
      vt 0.625 0.479471875
      vt 0.5 0.65625
      vn 0 -2.220446049250313e-16 1
      vn 0.7071067811865476 1.5700924586837752e-16 -0.7071067811865476
      vn 0 0.7071067811865477 -0.7071067811865475
      vn 0 -0.7071067811865475 -0.7071067811865477
      vn -0.7071067811865476 1.5700924586837752e-16 -0.7071067811865476
      usemtl m_c5b90dae-3a75-90c1-2280-8a6b9dc0fba2
      f 1/1/1 2/2/1 3/3/1 4/4/1
      f 2/5/2 1/6/2 5/7/2
      f 3/8/3 2/9/3 5/10/3
      f 1/11/4 4/12/4 5/13/4
      f 4/14/5 3/15/5 5/16/5

      Exporting also generates an mtl file and a png texture file:

      # Made in Blockbench 4.8.3
      newmtl m_c5b90dae-3a75-90c1-2280-8a6b9dc0fba2
      map_Kd kubejs:block/qqqqoo
      newmtl none

      Make sure usemtl m_c5b90dae-3a75-90c1-2280-8a6b9dc0fba2 in obj matches newmtl m_c5b90dae-3a75-90c1-2280-8a6b9dc0fba2 in mtl. mtllib qqqqoo.mtl in obj points to the mtl file; keeping them at the same level is fine by default.
      map_Kd in mtl specifies the texture path.
      Like vanilla models, place textures in assets/${modid}/textures/block (this tutorial uses a block example, so it is under block; for items, use item).

  • Point to the obj File

    • Vanilla Minecraft cannot load obj files directly, so you need a json model file that points to the obj file.

      {
          "loader": "forge:obj",
          "model": "kubejs:models/block/qqqqoo.obj",
          "flip_v": true,
          "textures": {
              "particle": "kubejs:block/qqqqoo"
          }
      }

      loader specifies the model loader type; here it is set to obj.
      model specifies the path to the obj model.
      flip_v controls texture flipping. Since obj UVs are vertically inverted relative to MC, set it to true.
      textures specifies textures to load; particle is used here for particle texture.

  • Define blockstate

    • When loading an obj model, you must provide a blockstate. It is not auto-generated for obj, so without it the block cannot resolve its model.

      {
          "variants": {
      	      "facing=down": {
      	   	      "model": "kubejs:block/qqqqoo",
      		      "x": 90
      	      },
      	      "facing=east": {
      		      "model": "kubejs:block/qqqqoo",
      		      "y": 90
      	      },
      	      "facing=north": {
      		      "model": "kubejs:block/qqqqoo"
      	      },
      	      "facing=south": {
      	          "model": "kubejs:block/qqqqoo",
      		      "y": 180
      	      },
      	      "facing=up": {
      		      "model": "kubejs:block/qqqqoo",
      		      "x": 270
      	      },
      	      "facing=west": {
      		      "model": "kubejs:block/qqqqoo",
      		      "y": 270
      	      }
          }
      }

    • Check Paths

      Place the mtl, obj, and the json model that points to the obj in assets/${modid}/models/block.
      Place the png texture in assets/${modid}/textures/block.
      The blockstate json file should be in assets/${modid}/blockstate.
      These files should be named after the block registry name.
      If the exported model appears offset in-game, adjust it in the modeling tool.

    References