led.md

LED

Derived from Device and Solid.

LED {
  MFColor color   [ 1 0 0 ]   # any color
  SFBool  gradual FALSE       # {TRUE, FALSE}
}

Description

The LED node is used to model a light emitting diode (LED). The light produced by an LED can be used for debugging or informational purposes. The resulting color is applied only on the first child of the LED node. If the first child is a Shape node, the emissiveColor field of its Material or PBRAppearance node is altered. If the first child is a Light node, its color field is altered. Otherwise, if the first child is a Group node, a recursive search is applied on this node in order to find which color field must be modified, so every Light, Shape and Group node is altered according to the previous rules. In terms of Light nodes, LED nodes can only accept PointLight and SpotLight nodes as children.

Note that Material and Light nodes that are going to be automatically altered by the LED functionality cannot be USE nodes.

Field Summary

• color: This defines the colors of the LED device. When off, an LED is always black. However, when on it may have different colors as specified by the LED programming interface. By default, the color defines only one color (red), but you can change this and add extra colors that could be selected from the LED programming interface. However, the number of colors defined depends on the value of the gradual field (see below).

• gradual: This defines the type of LED. If set to FALSE, the LED can take any of the color values defined in the color list. If set to TRUE, then the color list should either be empty or contain only one color value. If the color list is empty, then the LED is an RGB LED and can take any color in the R8G8B8 color space (16 million possibilities). If the color list contains a single color, then the LED is monochromatic, and its intensity can be adjusted between 0 (off) and 255 (maximum intensity).

LED Functions

wb_led_set

wb_led_get

%tab-component "language"

%tab "C"

#include <webots/led.h>

void wb_led_set(WbDeviceTag tag, int value);
int wb_led_get(WbDeviceTag tag);

%tab-end

%tab "C++"

#include <webots/LED.hpp>

namespace webots {
  class LED : public Device {
    virtual void set(int value);
    int get() const;
  }
}

%tab-end

%tab "Python"

from controller import LED

class LED (Device):
    def set(self, value):
    def get(self):

%tab-end

%tab "Java"

import com.cyberbotics.webots.controller.LED;

public class LED extends Device {
  public void set(int value);
  public int get();
}

%tab-end

%tab "MATLAB"

wb_led_set(tag, value)
value = wb_led_get(tag)

%tab-end

%end

Description

turn an LED on or off and read its status

The wb_led_set function switches an LED on or off, possibly changing its color. If the value parameter is 0, the LED is turned off. Otherwise, it is turned on.

In the case of a non-gradual LED (gradual field set to FALSE), if the value parameter is 1, the LED is turned on using the first color specified in the color field of the corresponding LED node. If the value parameter is 2, the LED is turned on using the second color specified in the color field of the LED node, and so on. The value parameter should not be greater than the size of the color field of the corresponding LED node.

In the case of a monochromatic LED (gradual field set to TRUE and color field containing exactly one color), the value parameter indicates the intensity of the LED in the range 0 (off) to 255 (maximum intensity).

In the case of an RGB LED (gradual field set to TRUE and color field containing an empty list), the value parameter indicates the RGB color of the LED in the range 0 (off or black) to 0xffffff (white). The format is R8G8B8: The most significant 8 bits (left hand side) indicate the red level (between 0x00 and 0xff). Bits 8 to 15 indicate the green level and the least significant 8 bits (right hand side) indicate the blue level. For example, 0xff0000 is red, 0x00ff00 is green, 0x0000ff is blue, 0xffff00 is yellow, etc.

The wb_led_get function returns the value given as an argument of the last wb_led_set function call.