Node Graph Basics¶

The node graph is your workspace in Nodo. Understanding how it works is essential to building procedural models efficiently.

What is a Node Graph?¶

A node graph is a visual representation of operations and data flow:

┌─────────┐     ┌───────────┐     ┌────────┐
│ Input A │────→│ Operation │────→│ Output │
└─────────┘     └───────────┘     └────────┘
       ↓
┌─────────┐
│ Input B │
└─────────┘

Think of it as: A flowchart where: - Nodes = Operations or generators - Connections = Data flowing between nodes - Parameters = Settings that control each node

Node Anatomy¶

Basic Structure¶

┌──────────────────────────┐
│     Node Title           │  ← Node name
├──────────────────────────┤
│  ○ Input 1               │  ← Input ports (left)
│  ○ Input 2               │
├──────────────────────────┤
│  Parameters shown here   │  ← Internal controls
├──────────────────────────┤
│               Output ○   │  ← Output port (right)
└──────────────────────────┘

Node Components¶

1. Title Bar - Node name (double-click to rename) - Node type/category - Status indicators

2. Input Ports (Left Side) - Circles where connections attach - Accept geometry from other nodes - Can have multiple inputs (e.g., Boolean node)

3. Parameters (Middle Section) - Adjustable values (sliders, spinboxes) - Expression mode available (click ≡ button) - Control the node's behavior

4. Output Port (Right Side) - Single circle sending data downstream - Can connect to multiple nodes

Data Flow¶

Left to Right¶

Data flows left → right in Nodo:

Generator → Modifier → Modifier → Output
(Creates)   (Changes)  (Refines)  (Result)

Example:

Sphere → Transform → Subdivide → Final Mesh

Execution Order¶

Nodo automatically determines execution order:

     A
    ↙ ↘
   B   C
    ↘ ↙
     D

Execution: A → B → C → D (parallel paths merge at D)

Key Point: You don't specify order - connections define it!

Node Types¶

1. Generator Nodes¶

Purpose: Create geometry from scratch

Examples: - Sphere, Box, Cylinder, Torus - Grid, Line

Characteristics: - No input ports (create data) - Generate base geometry - Controlled by parameters only

Use: Starting points for any model

2. Modifier Nodes¶

Purpose: Change existing geometry

Examples: - Transform, Extrude, Smooth - Subdivide, Mirror, Bend, Twist

Characteristics: - One input port (geometry to modify) - One output port (modified result) - Chain together for complex effects

Use: Refine and shape geometry

3. Boolean Nodes¶

Purpose: Combine multiple geometries

Examples: - Boolean (Union/Subtract/Intersect) - Merge (Combine without CSG)

Characteristics: - Multiple input ports - Combine or cut geometry - Order matters (A subtract B ≠ B subtract A)

Use: Complex shapes from simple primitives

4. Array Nodes¶

Purpose: Duplicate and distribute

Examples: - Array (linear/grid/circular) - Scatter (random distribution) - Copy to Points (instance at positions)

Characteristics: - Input: geometry to duplicate - Output: many copies - Powerful for patterns

Use: Repetition and instancing

5. Attribute Nodes¶

Purpose: Manage vertex/face data

Examples: - Attribute Create - Attribute Delete - Color

Characteristics: - Modify per-point/face attributes - Enable advanced workflows - Support expressions

Use: Data-driven modeling

6. Group Nodes¶

Purpose: Select and filter geometry

Examples: - Group (select by pattern/expression) - Group Delete (remove selected) - Group Combine (merge selections)

Characteristics: - Create named selections - Filter operations to subsets - Powerful with expressions

Use: Selective operations

Making Connections¶

How to Connect¶

Click and drag from an output port
Release on an input port
Connection appears as a line

Visual:

[Node A] ○────→ ○ [Node B]
        output  input

Connection Rules¶

✅ Can Connect: - Output → Input - One output → Many inputs (branching) - Compatible types (geometry → geometry)

❌ Cannot Connect: - Input → Output (wrong direction) - Input → Input - Output → Output

Disconnecting¶

Click the connection line → Select it
Press Delete or Backspace
Or drag output to empty space

Panning¶

Middle mouse button + drag
Or Space + Left mouse drag

Zooming¶

Mouse wheel scroll
Ctrl + Middle mouse drag

Framing¶

F key - Frame selected node(s)
A key - Frame all nodes

Node Operations¶

Creating Nodes¶

Method 1: Tab Menu 1. Press Tab in graph 2. Type to search (e.g., "sphere") 3. Click or press Enter

Method 2: Right-Click Menu 1. Right-click in graph 2. Navigate categories 3. Select node

Method 3: Keyboard Shortcuts - S - Add Sphere - B - Add Box - T - Add Transform - (See full list in Keyboard Shortcuts)

Selecting Nodes¶

Left-click - Select single node
Ctrl + Left-click - Add to selection
Click + Drag box around nodes - Multi-select
Ctrl + A - Select all

Moving Nodes¶

Left-click and drag node
Or select + arrow keys for precise placement

Deleting Nodes¶

Select node(s)
Press Delete or Backspace
Connections are removed automatically

Duplicating Nodes¶

Select node(s)
Ctrl + D - Duplicate
Connections are NOT copied

Copying Parameters¶

Ctrl + C on parameter value
Ctrl + V on target parameter
Or right-click → Copy/Paste Value

Execution Flow¶

Dependency Chain¶

Each node waits for its inputs:

A ───→ B ───→ C
       ↑
D ─────┘

Execution: A, D → B (when both ready) → C

Live Evaluation¶

Nodo evaluates on-demand:

You change a parameter
Node marks itself "dirty"
All downstream nodes mark dirty
Display node re-executes chain
Viewport updates

Result: Only affected nodes re-execute (efficient!).

Circular Dependencies¶

Not allowed:

A → B → C → A  ❌ Creates infinite loop

Nodo will detect and warn about cycles.

Best Practices¶

1. Organize Your Graph¶

Good Layout:

┌──────┐    ┌───────┐    ┌───────┐
│ Gen  │───→│ Mod 1 │───→│ Mod 2 │───→ Output
└──────┘    └───────┘    └───────┘

Bad Layout:

    ┌─────┐
    │Gen  │
    └──┬──┘
       ↓
    ┌──┴──────┐
    │  Mod    │←──┐
    └─────────┘   │
          ↓       │
       [Tangled mess]

Tips: - Keep flow left → right - Align nodes vertically when possible - Use space to group related nodes

2. Name Your Nodes¶

✅ "base_cylinder", "window_array", "roof_detail"
❌ "cylinder_1", "array_5", "merge_12"

How: Double-click title → Type new name

3. Use Comments¶

Future feature: Sticky notes to annotate graphs

Current: Use descriptive node names as documentation

4. Break Into Sections¶

Conceptual stages:

[Base Geometry] → [Primary Details] → [Secondary Details] → [Finishing]

Visually separate with spacing.

5. Avoid Spaghetti¶

Too many crossing connections = hard to read

Solution: - Rearrange nodes to minimize crossings - Consider using subgraphs (future feature)

Common Patterns¶

Linear Chain¶

A → B → C → D → Output

Use: Sequential operations (build, refine, finish)

Parallel Branches¶

    A
   ↙ ↘
  B   C
   ↘ ↙
    D

Use: Combine separate parts (e.g., base + details)

Scatter-Gather¶

      A
    ↙ ↓ ↘
   B  C  D
    ↘ ↓ ↙
      E

Use: Apply variations, then merge

Feedback Loop (via Parameters)¶

A → B → C
    ↑
    └─ ch("../c/output_value")

Use: One-way parameter references (not geometry cycles)

Graph vs. Timeline¶

Nodo is Spatial, Not Temporal¶

Not Like: - Video editing (timeline-based) - Animation software (keyframe-based)

More Like: - Programming flowcharts - Data processing pipelines - Spreadsheet formulas

Key Difference: - No "playhead" or "current time" - Graph is the complete procedure - Evaluate, don't animate (yet)

Debugging Your Graph¶

Node Not Updating?¶

Check: 1. Is it connected to the output chain? 2. Are inputs valid (connected nodes)? 3. Are parameters in valid ranges? 4. Any error indicators on node?

Unexpected Result?¶

Isolate: 1. Select node producing wrong result 2. Temporarily delete downstream nodes 3. Examine intermediate output 4. Narrow down problem node

Performance Issues?¶

Optimize: 1. Check for accidentally high poly counts 2. Disable expensive nodes while tweaking 3. Use lower resolution for preview 4. Optimize execution order

Advanced Techniques¶

Expression-Driven Graphs¶

Use expressions to automate:

Array Count = ceil($building_height / $floor_height)

Now array adapts to building height automatically!

Graph Parameters¶

Expose controls in Graph Parameters panel:

$master_scale - Controls all size parameters
$detail_level - Switches LOD variants
$random_seed  - Changes all randomization

Cross-Node References¶

Link parameters between nodes:

Cylinder radius = ch("../sphere/radius") * 0.5

Cylinder automatically half of sphere's size!

Keyboard Shortcuts¶

Essential graph shortcuts:

Action	Shortcut
Create Node	Tab
Delete	Delete / Backspace
Duplicate	Ctrl + D
Select All	Ctrl + A
Frame All	A
Frame Selected	F
Pan	MMB drag / Space + LMB
Zoom	Scroll wheel

See Full Shortcuts List

Next Steps¶

Understand Geometry - Geometry Types
Learn Attributes - Attributes
Use Groups - Groups
Try a Workflow - Architectural Modeling

Key Takeaways¶

✅ Node graphs = Visual flowcharts for 3D procedures ✅ Data flows left → right through connections ✅ Nodes = Generators, Modifiers, Booleans, Arrays, etc. ✅ Live evaluation - Changes propagate instantly ✅ Organize for readability (naming, layout, spacing) ✅ Think procedurally - Build generators, not static models

Remember: A good node graph is like good code - readable, organized, and maintainable!