Blockbench Texturing

Create and paint textures for 3D models using Blockbench MCP tools.

When the model should use Minecraft's own textures ("vanilla" or "default" textures, or a named block such as bricks or oak planks), use vanilla textures. It downloads Mojang's originals from the CDN before any painting or generation.

For animated texture sheets, use flipbook textures: generate artwork through the GPT Image 2.5 texture skill, convert measured sprite cells to a vertical strip, and configure one-frame UV dimensions and playback metadata.

Plan UVs Before Texture Detail

Carry forward the user's appearance/performance preference. For performance or balanced designs, allocate shared UV tiles for repeated braces/infills, seat ribs, seams, and mounting details before adding geometry. Paint small fasteners onto existing supporting faces; add aligned PBR maps when the target supports them. Reusing UVs alone does not reduce the geometry already present.

Fix texel density before sizing textures. Choose between tiled faces and a unique atlas; for low-poly glTF, collapse face UVs onto a palette atlas. Confirm whether the target accepts non-square or non-power-of-two images: Minecraft does not, while Hytale and Babylon.js do. Minecraft face UVs do not wrap, so repeat a tile by splitting faces. See real-time asset planning sections 7–9.

Inspect the target's box/per-face UV mode and effective UV dimensions before painting. UV units can differ from image pixels; formats with per_texture_uv_size use each face's texture dimensions. Preserve deliberate mirrored/repeated UV overlaps, and allocate unique space for asymmetric detail. Preview a checker or directional mark for stretching, orientation and seams. Match pixel density to the user's style and viewing distance; Minecraft pixel-art rules do not apply to every format. See format and delivery guidance.

Blockbench's native texture-template workflow can lay out UVs, but create_texture creates/imports an image and does not generate that layout. auto_uv_mesh maps faces and does not pack islands. For packed layouts, use a tool actually advertised by the running bundle or the native template/UV workflow; preserve an existing painted atlas before rearranging it.

Preserve UV Proportions and Material Scale

Read UV scale and distortion guidance before applying detailed materials, sharing swatches across different face sizes, or correcting stretched textures. Compute sampled image pixels per model unit along both face directions using the effective texture's frame and logical UV sizes. A shared material normally needs proportionate UV footprints, not the same full rectangle on every face.

Check both local stretching and scale differences between parts with a reversible checker, then inspect the actual grain/pattern. Prefer proportionate subregions, appropriate trim strips, or verified target-supported tiling. A bounded UV rectangle or larger image does not prove correct scale. Keep deliberate stretching for uniform materials or designed effects; a plain albedo with detailed PBR channels still needs the scale check.

Replace Repeated Geometry with a UV Tile

Use a small number of format-supported panels for repeated rail infills or X braces when the chosen viewing distance tolerates flat detail. Map the pattern onto those panels and keep the holes transparent. Reserve opaque regions for solid surfaces and pad atlas islands without filling intentional holes. Check edge-on views, both sides, filtering/mipmaps, and distant views for disappearing bars, halos, or texture bleed before removing the replaced geometry. Test transparent layers for overdraw; one cutout panel per bar defeats the reduction.

Choose the target's alpha-test/culling behavior explicitly; double-sided rendering and translucent blending have costs. Multiple textures are permitted when the format supports them, but importing images does not complete runtime material wiring. For Bedrock custom blocks, follow material-instance and texture delivery; entity bindings use a different workflow.

Generate a Native Texture Template

For a new atlas, enter a supported Edit mode and establish the intended outliner selection, then open the native action without accepting its defaults:

trigger_action: action="create_texture", confirmDialog=false

Inspect the returned app screenshot/dialog before using fill_dialog. The current native dialog commonly has name, type="template", resolution (pixel density), rearrange_uv, double_use (reuse matching faces), power, and padding. Send only fields present in that host's dialog. Example after inspecting its defaults:

fill_dialog: values="{\"name\":\"atlas\",\"type\":\"template\",\"rearrange_uv\":true}", confirm=true

Choose density, overlap reuse and padding for the target; the template's resolution is not a requested final atlas width. An empty outliner selection may select the whole model, and single-texture formats can process all eligible visible elements even with a partial selection. Check the operation's scope before confirming, especially on painted content. Generation may continue asynchronously: verify list_textures, actual UVs and get_texture after completion before painting. fill_dialog: confirm=false cancels the dialog; it is not a way to fill fields and leave it open. See the native texture generator and official template workflow.

Paint coordinates are image pixels. Pass an explicit texture_id to each paint tool when more than one texture exists. Layers and selections affect native painting; inspect the selected layer and existing selection before painting. layer_name names a new/renamed layer; for most layer actions the tool operates on the currently selected layer rather than resolving an arbitrary layer by name.

Available Tools

Texture Management

Paint Tools

Brush Management

Layers & Selection

UV Tools

Resources

Creating Textures

New Blank Texture

create_texture: name="skin", width=64, height=64, fill_color="#808080", layer_name="base"

Texture with Transparency

create_texture: name="overlay", width=32, height=32, fill_color=[0, 0, 0, 0], layer_name="base"

Separate UV Dimensions from Bitmap Resolution

In a format with per_texture_uv_size=true, create_texture accepts uv_width and uv_height together as positive numbers. Omit both to preserve the native defaults. The pair also works when importing image data; it sets logical UV dimensions after image decoding without resizing the bitmap.

# For an intended Generic Model with per_texture_uv_size=true
create_texture: name="paint_detail", width=128, height=64,
  uv_width=32, uv_height=16, fill_color="#808080", layer_name="base"
list_textures
# Inspect uv_size=[32,16], bitmap_size=[128,64], frame_size=[128,64]

This static image has four pixels per UV unit on each axis. Multiple textures can have different UV sizes in the same project, so use the face's effective texture dimensions for mapping. list_textures exposes uv_size, bitmap_size, and frame_size in the current bundle. Formats with project-wide UV dimensions reject per-texture overrides; inspect and edit the native project UV-size settings instead. Changing logical dimensions can change existing mapping, so preserve the intended pixel density and verify the result.

Apply to Element

create_texture requires layer_name whenever fill_color is supplied. Texture lookups accept a name or UUID; use the UUID from list_textures when names are ambiguous.

apply_texture: id="body", texture="skin", applyTo="all"

Painting

Basic Brush Stroke

paint_with_brush: texture_id="skin", coordinates=[
  {x: 10, y: 10},
  {x: 15, y: 12},
  {x: 20, y: 10}
], brush_settings={color: "#FF0000", size: 3, shape: "circle"}

Soft Brush

paint_with_brush: texture_id="skin", coordinates=[{x: 32, y: 32}],
  brush_settings={color: "#FFFFFF", size: 10, softness: 50, opacity: 128}

Fill Area

paint_fill_tool: texture_id="skin", x=16, y=16, color="#3366FF",
  fill_mode="color_connected", tolerance=0

The native fill API supports exact color matching only; nonzero tolerance is rejected.

Face/element fill modes depend on native geometry/UV context. Texture-pixel coordinates alone do not identify a model face. Use explicit rectangular painting for a known UV rectangle, or establish and verify the native target context before face filling. Inspect the result; a success message alone does not prove that only the intended face changed.

Shapes & Gradients

Draw Rectangle

draw_shape_tool: texture_id="skin", shape="rectangle",
  start={x: 0, y: 0}, end={x: 16, y: 16}, color="#FFCC00"

Draw Hollow Ellipse

draw_shape_tool: texture_id="skin", shape="ellipse_h",
  start={x: 8, y: 8}, end={x: 24, y: 24}, color="#000000", line_width=2

Apply Gradient

gradient_tool: texture_id="skin",
  start={x: 0, y: 0}, end={x: 0, y: 32},
  start_color="#87CEEB", end_color="#1E90FF"

Erasing

eraser_tool: texture_id="skin", coordinates=[{x: 10, y: 10}, {x: 12, y: 12}],
  brush_size=5, shape="circle", opacity=255

Color Picking

color_picker_tool: texture_id="skin", x=16, y=16
# Returns picked color, sets as active

Clone/Copy Brush

copy_brush_tool: texture_id="skin",
  source={x: 0, y: 0}, target={x: 32, y: 0},
  brush_size=8, mode="copy"

Brush Presets

Create Preset

create_brush_preset: name="soft_round", size=8, shape="circle",
  softness=30, opacity=200, color="#FFFFFF"

Load Preset

load_brush_preset: preset_name="soft_round"

Texture Layers

Create Layer

texture_layer_management: texture_id="skin", action="create_layer",
  layer_name="details"

Set Layer Opacity

texture_layer_management: texture_id="skin", action="set_opacity",
  opacity=75  # Operates on the selected layer; layer opacity is 0–100 percent

Merge Down

texture_layer_management: texture_id="skin", action="merge_down"  # Selected layer

Selections

Rectangle Selection

texture_selection: texture_id="skin", action="select_rectangle",
  coordinates={x1: 0, y1: 0, x2: 16, y2: 16}

Add to Selection

texture_selection: texture_id="skin", action="select_ellipse",
  coordinates={x1: 8, y1: 8, x2: 24, y2: 24}, mode="add"

Invert Selection

texture_selection: texture_id="skin", action="invert_selection"

Feather Edges

texture_selection: texture_id="skin", action="feather_selection", radius=2

UV Mapping

Cube UVs

Confirm get_cube_uv and set_cube_uv are advertised by get_capabilities: include_tools=true; older loaded bundles need reloading before these tools are available. Use a cube's actual UUID as id when a group has the same name.

get_cube_uv: id="body_geo"
# → {uuid, name, box_uv, autouv, uv_offset, mirror_uv, faces}
# Each face: uv, rotation, texture, texture_status, effective_texture, uv_size, bitmap_size, frame_size

# Move the atlas origin of an existing box-UV cube
set_cube_uv: id="body_geo", uv_offset=[16, 8], mirror_uv=false

# In an existing per-face-UV cube, edit one rectangle (UV units)
set_cube_uv: id="panel_geo", faces={north: {uv: [0, 0, 8, 4]}}

Choose the example matching the cube's inspected mode; box offsets and face rectangles are different workflows. Changing modes requires an explicit box_uv argument and a format that permits it; native conversion can reset rotations and enable disabled faces. The tool verifies that conversion succeeded and rolls back a refused conversion. Nonzero face rotations require the format's uv_rotation support. Explicit rectangles normally disable automatic remapping; Hytale preserves autouv=1 and requires rectangle extents to match the absolute base face dimensions, swapping width/height for 90/270-degree UV rotation. Matching offsets and mirrors are allowed, while changed extents are rejected before Undo. Hytale quads cannot use box UV. See the Hytale native UV behavior.

Per-face texture accepts an existing texture name/UUID, false for unassigned, or null to disable the face. Single-texture and per-group-texture formats restrict per-face assignments; use their existing global/group workflow. Hytale resolves textures through an attachment collection or the project default even when single_texture=false; the tool rejects non-null per-face assignments there. Reinspect after edits, including effective_texture, uv_size, bitmap_size, and frame_size. Convert UVs to pixels within a frame using frame_size / uv_size on each axis; bitmap_size includes the entire animated atlas. For a frame 64 pixels across 16 UV units, a UV coordinate of 4 is frame X=16.

Auto UV for Mesh

select_mesh_elements: mesh_id="ball", mode="face"  # Select the intended faces
auto_uv_mesh: mesh_id="ball", mode="project"  # project, unwrap, cylinder, sphere

project uses the active preview camera; unwrap creates an independent planar mapping per face and does not pack UV islands. cylinder and sphere use the mesh-local origin and each mapped face's effective UV dimensions, so inspect texture assignments first. Pass explicit returned face keys in faces to target only part of a mesh.

Set Custom UV

Mesh face and vertex keys are generated at runtime; cube direction names are not mesh face IDs. Retain the meshes[] entry returned by place_mesh as shown in the modeling skill, or inspect an existing mesh using get_mesh_info with include_uv=true.

This client orchestration example continues with the quad panel created in the modeling skill. call invokes the named MCP tool, checks isError, and decodes JSON results; variable expressions must be bound to actual returned values before sending tool arguments.

const uvCorners = [[0, 0], [16, 0], [16, 16], [0, 16]];
await call("set_mesh_uv", {
  mesh_id: panel.uuid,
  face_key: panel.face_keys[0],
  uv_mapping: Object.fromEntries(panel.vertex_keys.map((key, index) => [key, uvCorners[index]])),
});

UV values use Blockbench texture units, not normalized 0–1 coordinates. For existing faces, use faces.items[].key and that face's vertices perimeter order from inspection; key the UV map with those exact vertex IDs. Read each page using its independent next_offset until null, without geometry edits between pages. See the modeling skill's readMeshPages helper; add include_uv: true when reading existing UVs. Reinspect after topology changes.

Rotate UV

await call("rotate_mesh_uv", {mesh_id: panel.uuid, angle: "90", faces: [panel.face_keys[0]]});

Paint Settings

paint_settings: pixel_perfect=true, mirror_painting={enabled: true, axis: ["x"]},
  lock_alpha=true

Common Workflows

Paint an Existing Skin Layout

Use the target skin's actual UV template. The following coordinates are only examples for regions already confirmed in that template; a blank image and these strokes do not construct a valid player skin automatically.

# Create texture
create_texture: name="player_skin", width=64, height=64, fill_color="#C4A484", layer_name="base"

# Base colors
draw_shape_tool: texture_id="player_skin", shape="rectangle",
  start={x: 20, y: 20}, end={x: 27, y: 31}, color="#3366CC"

# Details with brush
paint_with_brush: texture_id="player_skin", coordinates=[{x: 10, y: 10}, {x: 12, y: 10}],
  brush_settings={color: "#000000", size: 1}, connect_strokes=false  # Separate eye pixels

# Apply
apply_texture: id="head", texture="player_skin"

Procedural Pattern

# Create base
create_texture: name="pattern", width=32, height=32, fill_color="#FFFFFF", layer_name="base"

# Draw grid
draw_shape_tool: texture_id="pattern", shape="rectangle_h", start={x: 0, y: 0}, end={x: 31, y: 31},
  color="#CCCCCC", line_width=1
draw_shape_tool: texture_id="pattern", shape="rectangle_h", start={x: 8, y: 8}, end={x: 24, y: 24},
  color="#999999", line_width=1

Tips

• Use pixel_perfect=true in paint_settings for clean pixel art
• Enable mirror_painting only after confirming the intended symmetry and native target context; disable it for asymmetric detail
• Use layers for non-destructive editing
• lock_alpha prevents painting outside existing pixels
• Use fill_mode="color_connected" to fill only touching same-color pixels
• Create brush presets for frequently used settings
• paint_with_brush connects points by default; set connect_strokes=false for separate stamps such as eyes or spots
• Inspect both get_texture and the rendered model after meaningful paint changes. For tiling blocks, check a repeated arrangement early; for animated assets, inspect surfaces revealed by poses. These practices follow the Minecraft style guide and Bedrock texturing guide.