Now we'll add some common utility functions that can be used by any of the patterns:
First we have the Red(), Blue() and Green() functions. These are the inverse of the Neopixel Color() function. They allow us to extract the Red, Blue and Green components of a pixel color.
// Returns the Red component of a 32-bit color
uint8_t Red(uint32_t color)
{
return (color >> 16) & 0xFF;
}
// Returns the Green component of a 32-bit color
uint8_t Green(uint32_t color)
{
return (color >> 8) & 0xFF;
}
// Returns the Blue component of a 32-bit color
uint8_t Blue(uint32_t color)
{
return color & 0xFF;
}
The DimColor() funtion uses Red(), Green() and Blue() to pull apart a color and re-construct a dimmed version of it. It shifts the red, green and blue components of the pixel color one bit to the right - effectively dividing by 2. Since red, green ane blue are 8-bit values, they will fade to black after the 8th call at the latest.
This function is used to create the fading tail effect in the Scanner pattern.
// Return color, dimmed by 75% (used by scanner)
uint32_t DimColor(uint32_t color)
{
uint32_t dimColor = Color(Red(color) >> 1, Green(color) >> 1, Blue(color) >> 1);
return dimColor;
}
Next we have the Wheel() function as used by the RainbowCycle pattern. This is borrowed pretty much as-is from the StrandTest example.
// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos)
{
WheelPos = 255 - WheelPos;
if(WheelPos < 85)
{
return Color(255 - WheelPos * 3, 0, WheelPos * 3);
}
else if(WheelPos < 170)
{
WheelPos -= 85;
return Color(0, WheelPos * 3, 255 - WheelPos * 3);
}
else
{
WheelPos -= 170;
return Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}
}
The Reverse() function will reverse the direction of pattern execution.
// Reverse direction of the pattern
void Reverse()
{
if (Direction == FORWARD)
{
Direction = REVERSE;
Index = TotalSteps-1;
}
else
{
Direction = FORWARD;
Index = 0;
}
}
And finally, we have the ColorSet() function to set all pixels to the same color synchronously. This is used by the Fader pattern.
// Set all pixels to a color (synchronously)
void ColorSet(uint32_t color)
{
for (int i = 0; i < numPixels(); i++)
{
setPixelColor(i, color);
}
show();
}
Page last edited February 08, 2015
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