isopxl

Documentation

From your first shape to your finished sprite. Updated for version 1.2.

Your first model

isopxl is a small 3D pixel art editor for iPhone. The workflow is simple: Model → Paint → Export. Your library starts with an editable bird so you can try the tools right away.

  1. Open a project from the library. Tap New project to start another project.
  2. In Model, select a face, point, or part and choose a tool.
  3. Switch to Paint to color the model’s surfaces.
  4. In Export, choose Fit or Relative sizing and check the views you want. Tap Export PNG, then choose Save to Files, AirDrop, or another destination in the iOS share sheet.

Projects save automatically. Tap Back to projects to return to the library.

Know your tools

These are the same pixel icons used in the app. Match the picture to the control on your screen. The examples below are a reference, not interactive buttons.

Select / pan
Tap to select. Drag with one finger to pan the view.
Move
Move selected geometry along X, Y, or Z.
Rotate geometry
Rotate selected geometry around an axis. To orbit the view, drag with two fingers.
Scale
Resize your selection uniformly or along one axis.
Extrude
Extend a selected face to add geometry.
Freeform subdivide
Drag a cut between edges or corners of a selected face.
Split selected face
Divide a face around its center.
Grid
Show or hide the modeling grid.
Snap
Turn snapping on or off for the active modeling tool.
Undo
Undo the last edit in this session.
Redo
Redo an undone edit.
Paint on model
Activate painting directly on the 3D surface.
Flat face editor
In Paint, select a face first, then open its flat pixel canvas.
Align to export camera
Match the painting view to the sprite camera.
Main menu
Find shapes, project export, the axis guide, and help.
Export
Open the iOS share sheet to save or send the selected output.

Model: faces, points, and parts

The three selection modes let you work at different levels:

  • Faces: select one surface to move, rotate, scale, extrude, or subdivide.
  • Points: select vertices to reshape the model. Choose X, Y, or Z to move them along an axis.
  • Parts: select a connected shape, then move, rotate, scale, duplicate, or delete it.

Open the main menu’s Add shape submenu for a cube, wedge, cylinder, cone, UV Sphere, or Icosphere. UV Sphere is the new name for Low Poly Sphere. It uses rings of faces; Icosphere uses triangular faces. Newly added shapes are selected so you can position them.

Use the grid to judge shape size

Each square on the modeling grid is 1 × 1 modeling unit. A default cube is 2 units wide, deep, and tall, so its footprint spans two grid squares in each direction. Use it as a starting reference: a cube scaled uniformly to 50% is one grid square wide and deep. Judge other shapes against the same grid to keep their proportions consistent.

With Snap enabled, movement uses quarter-unit steps: four steps cover one grid square. Toggle the Grid tool to show or hide the guide. Zooming changes how large the grid looks on screen, but its spacing stays one modeling unit.

Grid squares are modeling units, not export pixels. For a 64 × 64 sprite, build the proportions you want, then check the Export preview to judge how the shapes read at that size. Fit sizing fits the model to the chosen size; Relative sizing uses a consistent number of pixels per tile. See sprite export sizing for details.

Move, rotate, and scale

Select something, choose a tool and axis, then drag its handle. Rotation uses a ring. Scale offers All for uniform resizing, plus X, Y, and Z for stretching. The + and − buttons also make adjustments.

Snap toggles snapping: movement uses quarter units, rotation uses 15° steps, and scaling uses 10% steps. Turn it off for free adjustments.

Extrude and subdivide

Select a face and use Extrude to extend it. Use the freeform subdivision tool to drag a cut between edges or corners. The separate Split selected face action divides a face around its center. Painted textures stay attached as you edit.

Work with whole shapes

Select connected part and Select whole model are in the main menu. Join all shapes groups your existing shapes for selection; it does not perform a Boolean union or remove internal faces.

Undo and redo let you revisit changes during the current editing session.

Paint: color in 3D or on a flat face

Choose Paint on model to paint directly on the model with one finger. Two fingers orbit the model, and pinching zooms. Painting can continue across face boundaries.

Pencil, Line, and Circle paint square surface pixels with the same physical size across the model, including narrow or sloping faces. A starter cube has 16 pixels along each edge. Zooming changes their size on screen; viewing a face at an angle makes its squares look foreshortened. Existing painted details are preserved.

The Draw button, marked with a small pixel corner, shows your last-used Pencil, Line, or Circle tool. When another tool or face selection is active, tap Draw once to resume that drawing tool. Tap Draw while it is active to open the Pencil, Line, and Circle menu. This works on the model and in the flat face editor.

  • Pencil: paint with the selected color.
  • Line: drag from the first endpoint to the second.
  • Circle: drag from the center outward to set the radius of a circle outline.
  • Fill: fill a region on the face you touch.
  • Eraser: restore the opaque base color; it does not cut holes in the model.
  • Picker: sample a color from the model.

Lines and circles preview while you drag and commit when you release. Undo removes the whole shape in one step. Both tools work on the model and in the flat face editor. On the model, shapes project onto visible surfaces; in the flat editor, they stay within the face boundary.

For precise pixel work, choose Select a face, tap a face, then tap Open face pixel editor. The flat editor button becomes available after you select a face. The flat canvas shows the face at its true proportions, viewed from the outside, so left and right match the model. Paint within the outlined face, pinch to zoom, and use two fingers to pan. The same tools and square grid work in both views.

The palette menu includes built-in palettes, your saved palettes, and colors used in the project. Add a color with the picker or a six-digit HEX value. Long-press a swatch to edit or remove it. Editing a built-in palette creates a personal copy.

The small sprite preview follows the export camera. Tap Align to export camera to align the paint view with it.

Import Lospec palettes

Visit Lospec’s palette list in your browser, choose a palette, and choose Open in app. Isopxl downloads the colors into My palettes and selects the palette for your open model.

If no model is open, the palette is saved in My palettes for you to choose later. Opening the same named palette with identical colors reuses the saved copy. Regular PNG and HEX file downloads are not imported through this integration. Downloading a palette requires an internet connection.

Export isometric pixel-art sprites

Choose PNG in Export, then choose a mode under Sprite size.

  • Fit (max px): choose 16, 32, 64, or 128 px as the maximum artwork size. The sprite fits within that limit, and unused canvas margins are trimmed automatically without smoothing or resampling the pixels. The resulting square PNG is trimmed around the artwork; outlines and their surrounding margin can affect the final image dimensions.
  • Relative (px/tile): choose 16, 32, or 64 pixels per tile to keep characters, props, and scenery at the same scale. These values describe the projected width of a ground tile, not the PNG dimensions. One tile spans two model units, matching the starter cube’s footprint. A 32-pixel-wide tile appears as a 32 × 16 diamond in the sprite view.

Image dimensions are automatic in both modes. In Relative mode, the canvas grows to contain every view, including tall models and outlines, without shrinking the model. If the sprite exceeds the 1024-pixel canvas limit, choose fewer pixels per tile.

Relative mode centers the model’s ground footprint at its lowest point. All directions share the same ground anchor and canvas. In Fit mode, the views retain the same model scale, but their trimmed image dimensions can differ. The floor grid and gold ground marker are preview guides and do not appear in exported sprites.

Open More export settings to choose 4, 8, or 16 directions around the model. The default is four. Tap a thumbnail to preview its angle, then use the separate checkbox to include or exclude that view. Select all includes every direction in the current set; Deselect all clears the selection. Select at least one view to export. The direction count is a setting for the current editing session. The single Export PNG button sends a separate transparent PNG for each checked view to the iOS share sheet.

Under Appearance, choose Flat or Shaded and optionally enable Outline. Every direction uses the classic 30° pixel-art camera elevation.

PNG filenames use your project name, the rendered image size, and the view number, such as Oak Tree-64px-view1.png. Rename the project in the library to change the name used for future exports.

The zoom controls change only the preview, not your saved image. Tap Export PNG to open the iOS share sheet with the checked views as separate transparent PNGs. Choose Save to Files, AirDrop, Messages, or another compatible app. The available destinations depend on the apps installed and how many files they support.

Export a textured 3D model

OBJ export is included in the one-time unlock. Choose OBJ, then tap Export OBJ to open the iOS share sheet. Choose Save to Files, AirDrop, or another compatible destination.

The share sheet receives three files: model.obj, model.mtl, and texture.png. No ZIP is created. Save or send all three together and keep them in the same folder when importing into Blender or another compatible 3D tool.

Set texture interpolation to Closest in Blender or Point in Unity for crisp pixel textures. PNG sprite size, tile scale, sprite shading, and outlines do not change the OBJ export.

Save, share, and back up projects

Tap a project’s name in the library to rename it. Use Select to duplicate, share, or delete projects.

Export editable project in the editor menu saves an .isopxl file with the geometry, textures, palette, and export settings. The library’s Share action also creates editable project files. Use Import to open an .isopxl file or a compatible older .json file as a new project.

Projects are stored locally in the app. Keep exported copies of important work in Files or another location you control. Deleted projects are hidden from the library and may remain in local app storage for recovery; there is no in-app Trash screen.

Free exports and the one-time unlock

All modeling and painting tools are available for free. You get three completed PNG export batches. A completed export counts as one batch, whether you export one view or multiple views from a set of 4, 8, or 16 directions. Cancelling the share sheet or a reported export failure does not use an export, and editable project backups do not count.

The one-time purchase unlocks unlimited PNG exports and OBJ export. Open Purchase Isopxl… in the main menu to see the current App Store price.

Already purchased? Choose Restore Purchases in the purchase sheet while signed into the Apple Account used to buy the unlock. An internet connection may be required.