A color gradient is a special list that defines a range of colors that you can smoothly interpolate between. A simple example is a gradient from red to white:
list("red", "white")
// OR
list(0, "red", 1, "white")Applying a number like 0.2 to this gradient would give you a color that’s 20% of the way from red to white. More complex gradients however are also possible.
The format of a gradient is a list that contains a number (the position along the gradient, from 0 to 1 unless you use values outside that range) followed by a color. You can have as complex a gradient as you like. If you reuse the same number twice in a row, the gradient will have a sudden color change at that point.
It is also possible to skip numbers or colors, and they will be filled in automatically with the previous number or color. The exceptions are at the beginning and ends of the list; at the end of the gradient, the last color is assigned a number 1 by default, and the first is assigned 0. If you skip colors at the beginning, they will be filled in with the first color you use.
Include “loop” anywhere in the list to make this a looped gradient. If you don’t, any numbers outside the gradient’s range will be clamped to that range. E.g., in a normal gradient ranging from 0 to 1, a number of 1.2 is interpreted as 1 without a loop and 0.2 with a loop.
Here are some more examples:
// color wheel; ranges 0 to 6 and loops
list(0, "#f00", 1, "#ff0", 2, "#0f0", 3, "#0ff", 4, "#00f", 5, "#f0f", 6, "#f00", "loop")
// 10% each red, yellow, green, blue, with a 20% transition zone between each
// notice no color follows 0.4 or 0.7, so the previous color is used
list(0.1, "#f00", 0.3, "#ff0", 0.4, 0.6, "#008000", 0.7, 0.9, "#00f")
// green and black stripes
list(0.5, "#008000", 0.5, "#000000", "loop")You can also include “space” in the list, and give it an associated value that describes the color space this gradient uses to interpolate between colors. For instance, "space"=COLORSPACE_HSL will use HSL interpolation instead of the default RGB. See Color space for more information.
// color wheel with a different color space
list(0, "#f00", 3, "#0ff", 6, "#f00", "loop", "space"=COLORSPACE_HSLA)Currently, color gradients are only used by particle effects and the gradient proc. With particles, if you use a gradient the particle’s color is given as a number, and that number is used to look up its real color from the gradient. The number can change over time, thus changing the particle’s color.