Add support for touch events

[ThomasVille]

Hi and thanks for the work on this crate.

I was wondering if there was any plan on supporting touch events in this crate?

If not, maybe I can work on a PR to add this?

I can already see that in WASM on Firefox I can use one finger to rotate the camera, but I can't pan/move the camera with two fingers.

FYI, here's what Claude Code suggests:

Plan: Add Touch Events Support to Bevy Blendy Cameras

Current State Analysis

The codebase already has partial touch support:

• Touches resource is imported and used in active_viewport_data_system (src/lib.rs:287)
• Basic touch position detection is implemented for viewport detection (src/lib.rs:219-228)
• Touch activation detection exists (src/lib.rs:338-340) but only for initial camera selection
• However, actual touch gesture handling for camera controls is completely missing

Proposed Implementation

1. Extend MouseKeyTracker for Touch Events

File: src/input.rs

• Add touch-specific fields to MouseKeyTracker struct:
  • touch_orbit: Vec2 - single finger orbit gestures
  • touch_pan: Vec2 - two-finger pan gestures
  • touch_zoom: f32 - pinch-to-zoom gestures
  • active_touches: u8 - count of active touches
• Import TouchInput events from Bevy

2. Implement Touch Gesture Recognition

File: src/input.rs - Update mouse_key_tracker_system

• Single touch: Orbit camera (equivalent to middle mouse drag)
• Two touches:
  • Pan camera when moving together
  • Zoom camera when distance changes (pinch gesture)
• Three+ touches: Ignore to avoid conflicts
• Handle touch lifecycle (Started, Moved, Ended, Cancelled)

3. Add Touch Configuration Options

Files: src/orbit.rs and src/fly.rs

• Add touch sensitivity settings:
  • touch_orbit_sensitivity: f32
  • touch_pan_sensitivity: f32
  • touch_zoom_sensitivity: f32
• Add touch enable/disable flags:
  • enable_touch_controls: bool (default: true)

4. Update Camera Controllers

Files: src/orbit.rs and src/fly.rs

• Modify orbit/fly systems to consume touch input from MouseKeyTracker
• Implement touch-specific behavior:
  • Orbit mode: Single finger orbit, two finger pan/zoom
  • Fly mode: Single finger rotate, two finger forward/backward movement

5. Handle Touch-Mouse Conflicts

File: src/input.rs

• Implement priority system: active touches disable mouse input
• Ensure smooth transitions between touch and mouse input
• Reset gesture state when switching input methods

6. Update Dependencies

File: Cargo.toml

• Ensure Bevy touch features are enabled (already included in bevy_window/bevy_winit)

Technical Considerations

• Gesture Detection: Use touch position deltas and distances for pan/zoom calculations
• Multi-touch Handling: Track individual touch IDs to maintain gesture consistency
• Platform Compatibility: Support iOS, Android, and touch-enabled desktop platforms
• Performance: Efficient touch tracking without impacting frame rates
• Backward Compatibility: All existing mouse/keyboard controls remain unchanged

Expected Outcome

Users will be able to:

• Single finger: Orbit camera around focus point
• Two fingers: Pan camera view and pinch-to-zoom
• Seamless switching: Between touch and mouse/keyboard controls
• Full compatibility: On mobile, tablet, and touch-enabled desktop devices

[thmxv]

I have nothing against it. I even would like it to be present for the users of this crate.

The base code is based on bevy_panorbit_camera and has some basic touch support.

The main issue is that I do not have an easy way to test touch screen. The only way for me to do that would be to use an android build on my daily use phone. Maybe there is another way that I am not aware. I just basically never use touchscreen and use my phone only for calling/messaging. I am probably too old :/

Anyway, any contribution is welcome.

I would recommend checking the code of bevy_panorbit_camera and see what they do differently.

[ThomasVille]

I do have a laptop with a touch screen so I can test locally without much hassle.

I can see that bevy_panorbit_camera supports touch controls so it might not be that hard to add:

Default touch controls:

One finger - Orbit
Two fingers - Pan
Pinch - Zoom