Custom Dynamic Brush Tilt Curves in GIMP

Configuring custom dynamic brush curves for tablet tilt sensitivity in GIMP allows you to control brush parameters such as size, opacity, and angle based on the physical tilt of your stylus. This guide explains how to set up drawing tablet tilt inputs, access the Paint Dynamics Editor, and manipulate custom response curves to achieve natural and precise brush behavior.

1. Verify Tablet Tilt Support in GIMP

Before creating custom curves, ensure your tablet is configured properly:

  1. Connect your graphics tablet and open GIMP.
  2. Go to Edit > Input Devices.
  3. Select your stylus from the device list.
  4. Set the Mode to Screen.
  5. Confirm that the tilt axes (Tilt X and Tilt Y) are recognized and click Save.

2. Open the Paint Dynamics Dialogs

You need two dockable dialogs to manage and edit dynamics:

  1. Go to Windows > Dockable Dialogs > Paint Dynamics.
  2. Go to Windows > Dockable Dialogs > Paint Dynamics Editor.

3. Create a New Paint Dynamic

GIMP does not allow editing the default, built-in dynamics. You must create a custom profile:

  1. In the Paint Dynamics dialog, click the Create a new dynamics button at the bottom (the blank page icon).
  2. A new dynamics asset will open inside the Paint Dynamics Editor.
  3. Rename the dynamics profile (e.g., "Custom Tilt Shading") at the top of the panel.

4. Map Tilt to Brush Behaviors

In the Paint Dynamics Editor, you will see a matrix with input variables along the top row and output behaviors along the left column:

  1. Locate the Tilt column.
  2. Check the boxes for the parameters you want tilt to influence, such as:
    • Size: Changes brush radius as the pen tilts.
    • Opacity: Adjusts transparency based on angle.
    • Aspect Ratio: Flattens the brush tip when tilting, simulating a flat chisel marker or pencil edge.
    • Angle: Rotates the brush tip along with the stylus direction.

5. Customize the Dynamics Curves

Once a parameter is checked, you can adjust the specific curve mapping:

  1. Check the box labeled Use dynamic curve under the matrix if it appears, or select the specific mapping tab (e.g., Size or Opacity) located below the matrix in the Paint Dynamics Editor.
  2. Select the specific curve corresponding to your input (e.g., the curve for Tilt).
  3. Click and drag the control points on the graph to customize the curve:
    • Linear Slope (Bottom-Left to Top-Right): Gradual, direct increase in the parameter as tilt increases.
    • S-Curve: Smooths out sudden tilt shifts, providing stable behavior at extreme angles and sensitivity in the middle range.
    • Inverted Curve (Top-Left to Bottom-Right): Decreases the output value as the pen tilts further from the vertical position.
  4. Click anywhere along the line to add new control points for fine-tuned responses.

6. Apply and Test the Brush Dynamics

  1. Select the Paintbrush tool (or any other dynamic-compatible painting tool) from the Toolbox.
  2. In the Tool Options panel, locate the Dynamics section.
  3. Click the dynamics icon and select your newly created custom tilt preset.
  4. Draw on the canvas while tilting the stylus at various angles to test the custom response curves.