Canvas2DMX

Troubleshooting

Quick fixes for common issues when using Canvas2DMX with Processing.

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🖥️ Colors look wrong / always white

Likely: HiDPI scaling or sampling the wrong pixels.

Fix

1. Force 1× pixel scale:

   void settings() { size(400, 300); pixelDensity(1); }
   

2. Confirm mapping on-screen:

   c2d.setShowLocations(true);
   c2d.showLedLocations();
   

3. Make sure you mapped an LED:

   c2d.setLed(0, width/2, height/2);
   

4. Sample after drawing:

   // draw scene...
   int[] colors = c2d.getLedColors();
   c2d.visualize(colors);
   c2d.showLedLocations();
   

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🔌 DMX not connecting (no light output)

Likely: Wrong device selection, drivers, or permissions.

Fix

1. Try alternate initializers (DMX4Artists):

   dmx = new DMXControl(0, 512);                          // first device
   dmx = new DMXControl("SERIAL_NUMBER", 512);            // by serial
   dmx = new DMXControl("/dev/tty.usbserial-XXXX", 512);  // explicit path
   

2. Verify you’re sending:

   if (dmx != null) c2d.sendToDmx((ch, val) -> dmx.sendValue(ch, val));
   

3. OS tips:

   • macOS: System Settings → Privacy & Security (allow serial).
   • Windows: Install FTDI/ENTTEC drivers, check COM port.
   • Linux: Add user to dialout/uucp, check /dev/ttyUSB* perms.

4. Prove data is generated:

   int[] frame = c2d.buildDmxFrame(32);
   println(java.util.Arrays.toString(frame));
   

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📁 Library not showing in Processing

Likely: Wrong install path.

Fix

1. Check Processing Sketchbook Location (Preferences).

2. Ensure the folder exists:

   <Sketchbook>/libraries/canvas2dmx/
   

3. Reinstall & restart Processing:

   ./gradlew deployToProcessingSketchbook
   

   Or set a custom path in gradle.properties:

   sketchbook.dir=/Users/you/Documents/Processing4
   

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🎛️ Fixture colors wrong (e.g., red/green swapped)

Likely: Channel pattern mismatch or dimmer not set.

Fix

c2d.setChannelPattern("rgb");        // or "drgb", "drgbsc", etc.
c2d.setDefaultValue('d', 255);       // full brightness if using dimmer 'd'
c2d.setDefaultValue('s', 0);         // strobe off
c2d.setStartAt(1);                   // DMX is 1-based

Match your fixture’s manual.

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🗺️ Markers off / some LEDs stay black

Likely: Off-canvas mapping or out-of-bounds sample.

Fix

int n = c2d.getMappedLedCount();
for (int i = 0; i < n; i++) {
  int pos = c2d.getLedPixelLocation(i); // -1 = unmapped
  if (pos >= 0) println("LED " + i + " → pixel " + pos);
}

Re-map to valid x,y inside 0..width-1, 0..height-1. Ensure you don’t clear the screen after getLedColors().

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🏃 Low performance / high CPU

Fix

• Map fewer LEDs, simplify drawing.

• Limit frame rate:

  void setup() { frameRate(30); }
  

• Throttle logs:

  if (frameCount % 30 == 0) println("debug...");
  

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🌈 Gamma/brightness feels off

Fix

c2d.setResponse(1.2f);                 // 1.0 = linear
c2d.setTemperature(0.15f);             // -1 warm … +1 cool
float[] curve = {0.0, 0.05, 0.2, 0.5, 0.8, 1.0}; // overrides response()
c2d.setCustomCurve(curve);

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🧪 Verify pipeline without hardware

Log a tiny preview periodically:

if (frameCount % 30 == 0) {
  c2d.sendToDmx((ch, val) -> { if (ch <= 16) println("ch " + ch + " = " + val); });
}

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🆘 Still stuck?

1) First, try the included examples: Basics, StripMapping, InteractiveDemo.

2) If the problem persists, open an issue here:
👉 Open an issue

Please include:

• OS & version: (macOS 14.5 / Windows 11 / Ubuntu 22.04)
• Processing version: (e.g., 4.3)
• Canvas2DMX version: (release tag or library.properties)
• DMX backend: (DMX4Artists version if applicable)
• Controller & connection: (model, serial/COM path, e.g., /dev/tty.usbserial-B001N0ZB)
• Sketchbook path: (Processing Preferences → Sketchbook Location)
• Fixture config: startAt, setChannelPattern(...), any setDefaultValue(...)
• LED mapping details: how many LEDs, mapping method used (strip/ring/grid)
• Minimal reproducible sketch: a short sketch that triggers the issue
• Console output / error messages: copy/paste the relevant lines
• Steps to reproduce: numbered list (what you did, what you expected, what happened)

Tip (no hardware): preview DMX output in console

   // Log the first 16 channels about twice per second
  if (frameCount % 30 == 0) {
    c2d.sendToDmx((ch, val) -> {
      if (ch <= 16) println("ch " + ch + " = " + val);
    });
  }

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📚 Learn More

• Canvas2DMX — repo link
• Getting Started — installation and first sketch
• Troubleshooting — common issues and fixes
• Develop — contributing and building from source
• Release — packaging and Contribution Manager

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📜 License

MIT License © 2025 Studio Jordan Shaw

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