> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mentraglass.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Display Glasses

> Build apps for glasses with screens - G1, Vuzix

**Display glasses have screens for showing content but no cameras.** Examples: Even Realities G1, Vuzix Z100. These devices are ideal for information display and heads-up interfaces.

## Common Display Glasses

### Even Realities G1

* **Display**: Green monochrome, 640×200 resolution
* **Microphone**: Yes
* **Speaker**: No (audio through phone)
* **Camera**: No
* **Buttons**: No
* **LEDs**: No

```typescript theme={null}
// G1 capabilities
{
  modelName: "Even Realities G1",
  hasDisplay: true,
  hasCamera: false,
  hasMicrophone: true,
  hasSpeaker: false
}
```

### Vuzix Z100

* **Display**: Green monochrome
* **Microphone**: No
* **Speaker**: No
* **Camera**: No
* **Buttons**: No
* **LEDs**: No

```typescript theme={null}
// Z100 capabilities
{
  modelName: "Vuzix Z100",
  hasDisplay: true,
  hasCamera: false,
  hasMicrophone: false,
  hasSpeaker: false
}
```

## Building for Display Glasses

### Check Display Capabilities

```typescript theme={null}
protected async onSession(session: AppSession, sessionId: string, userId: string) {
  const caps = session.capabilities;
  if (!caps?.hasDisplay) {
    session.logger.warn('No display available');
    return;
  }

  const display = caps.display;
  if (display) {
    session.logger.info('Resolution:', display.resolution);
    session.logger.info('Is color:', display.isColor);
    session.logger.info('Max lines:', display.maxTextLines);
  }
}
```

### Adapt to Display Size

```typescript theme={null}
const maxLines = caps.display?.maxTextLines || 3;

if (maxLines < 5) {
  // Small display - brief message
  session.layouts.showTextWall('Done!');
} else {
  // Larger display - more detail
  session.layouts.showReferenceCard('Complete', 'Task finished successfully');
}
```

### Monochrome Displays

```typescript theme={null}
const isColor = caps.display?.isColor;

if (!isColor) {
  // Monochrome - use high contrast
  session.layouts.showTextWall('Status: Active');
  // Avoid complex graphics
} else {
  // Color display available
  session.layouts.showTextWall('✓ Status: Active');
}
```

## Audio Routing

**Display glasses without speakers route audio to the phone:**

```typescript theme={null}
if (!caps.hasSpeaker) {
  // Audio plays through phone
  await session.audio.speak('Hello!');

  // User hears through phone speaker or Bluetooth headphones
}
```

## Input Methods

**G1 has microphone for voice input:**

```typescript theme={null}
if (caps.hasMicrophone) {
  session.events.onTranscription((data) => {
    if (data.isFinal) {
      session.layouts.showTextWall(data.text);
    }
  });
}
```

**Vuzix has no microphone - use phone for input:**

```typescript theme={null}
// Voice input happens through phone's microphone
session.events.onTranscription((data) => {
  // Still works - uses phone mic
});
```

## Display Best Practices

**Keep text concise:**

```typescript theme={null}
// ✅ Good - readable
session.layouts.showTextWall('Message sent');

// ❌ Avoid - too much text
session.layouts.showTextWall(
  'Your message has been successfully sent to the recipient and they will receive it shortly'
);
```

**Use appropriate layouts:**

```typescript theme={null}
// Simple status
session.layouts.showTextWall('Ready');

// Structured info
session.layouts.showReferenceCard(
  'Weather',
  'Sunny\n72°F\nHumidity: 45%'
);

// Two-part content
session.layouts.showDoubleTextWall({
  topText: 'Question:',
  bottomText: 'What is 2 + 2?'
});
```

**Test on actual hardware:**

* Display sizes vary
* Text may be smaller/larger than expected
* Green monochrome has limited contrast

## Example App

```typescript theme={null}
class DisplayGlassesApp extends AppServer {
  protected async onSession(session: AppSession, sessionId: string, userId: string) {
    const caps = session.capabilities;

    if (!caps?.hasDisplay) {
      session.logger.warn('No display - audio only');
      await session.audio.speak('Welcome');
      return;
    }

    // Show welcome on display
    session.layouts.showTextWall('Voice Assistant Ready');

    // Use microphone if available
    if (caps.hasMicrophone) {
      session.events.onTranscription((data) => {
        if (data.isFinal) {
          this.handleCommand(session, data.text);
        }
      });
    } else {
      // Phone microphone still works
      session.events.onTranscription((data) => {
        if (data.isFinal) {
          this.handleCommand(session, data.text);
        }
      });
    }
  }

  private handleCommand(session: AppSession, text: string) {
    session.layouts.showTextWall(`You said: ${text}`);

    // Speak response if no speaker on glasses
    if (!session.capabilities?.hasSpeaker) {
      session.audio.speak('Processing');
    }
  }
}
```

## Next Steps

<CardGroup cols={2}>
  <Card title="Camera Glasses" icon="camera" href="/app-devs/core-concepts/hardware-capabilities/camera-glasses">
    Mentra Live - camera features
  </Card>

  <Card title="Display & UI" icon="display" href="/app-devs/core-concepts/display/layouts">
    Using layouts and dashboard
  </Card>

  <Card title="Audio" icon="volume" href="/app-devs/core-concepts/speakers/text-to-speech">
    Audio features
  </Card>

  <Card title="Overview" icon="microchip" href="/app-devs/core-concepts/hardware-capabilities/overview">
    Back to overview
  </Card>
</CardGroup>