About

This is library for color manipulations. It allows you to extrude and pack color channels, convert the RGB color model to HSB and vice versa, perform alpha blending, generate color transitions and convert the color to 8-bit format for the OpenComputers palette.

Installation

Source code is available here: You can download library to computer via single command:

wget https://github.com/IgorTimofeev/Color/blob/master/lib/Color.lua /lib/color.lua -f

Working with color channels

color.RGBToInteger( red, green, blue ): int integerColor

Type	Parameter	Description
byte [0; 255]	red	Red color channel
byte [0; 255]	green	Green color channel
byte [0; 255]	blue	Blue color channel

The method packages three color channels and returns a 24-bit integer variable

color.integerToRGB( integerColor ): byte red, byte green, byte blue

Type	Parameter	Description
int	integerColor	Color in 0xRRGGBB format

The method extrudes three color channels from a 24-bit integer variable. The values of the returned data are in the range [0; 255]

Color processing

color.blend( firstColor, secondColor, secondColorTransparency ): int blendedColor

Type	Parameter	Description
int	firstColor	First color
int	secondColor	Second color
float [0.0; 1.0]	secondColorTransparency	Second color transparency

Mix two colors considering the transparency of the second color. For example, if you perform this operation on 0xFF0000 and 0x000000 colors with a 0.5 transparency of second one, the result will be 0x7F0000 (dark red)

color.transition( firstColor, secondColor, position ): int transitionColor

Type	Parameter	Description
int	firstColor	First color
int	secondColor	Second color
float [0.0; 1.0]	position	Position of transition point from first color to second

The method generates a transitive color between first and second ones, based on the transition argument, where the value 0.0 is equivalent to the first color, and 1.0 is the second color. For example, if you perform this operation on 0x000000 and 0xFFFFFF colors with transition position equals 0.5, then the result will be 0x7F7F7F (gray)

Conversion of color models

color.RGBToHSB( red, green, blue ): int hue, float saturation, float brightness

Type	Parameter	Description
byte [0; 255]	red	Red color channel
byte [0; 255]	green	Green color channel
byte [0; 255]	blue	Blue color channel

The method converts three color channels of the RGB color model to the HSB (HSV) color model and returns the corresponding result. The returned hue value is in the range [0; 360], and saturation and brightness - in the range [0.0; 1.0].

For convenience, there is also a method color.integerToHSB(int integerColor): int hue, float saturation, float brightness

color.HSBToRGB( hue, saturation, brightness ): byte red, byte green, byte blue

Type	Parameter	Description
int [0; 360]	hue	Hue
float [0.0; 1.0]	saturation	Saturation
float [0.0; 1.0]	brightness	Brightness

The method converts the parameters of the HSB color model (HSV) into three color channels of the RGB model and returns the corresponding result. For convenience, there is also a method color.HSBToInteger(int hue, float saturation, float brightness): int integerColor

Color compression

color.to8Bit( 24BitColor ): byte 8BitColor

Type	Parameter	Description
int	24BitColor	Color in 0xRRGGBB format

This method refers to 256-color OpenComputers palette and returns the color index that best matches the passed value using the same search method as in gpu.setBackground(color) do. As a result, a variable is returned in the range [0; 255], which can be used to write to a binary file, allowing you to save extra memory. I draw your attention that the method is quite slow, and is not suitable for drawing graphics on the screen in realtime.

color.to24Bit( 8BitColor ): int 24BitColor

Type	Parameter	Description
int	8BitColor	Index of OpenComputers palette

The method allows you to convert the 8-bit index created by the color.to8Bit method to 24 bit integer color value