Pencil Code Reference > color names


color names

The CSS standard has 140 named colors (and 10 alternate color names).

Click a color to try it.

These colors can be used when drawing with pen, dot, box, fill, or when using CSS properties. Colors can also be created using numbers, using the rgb and hsl functions.

Transparency and Erasing

It is possible to use semitransparent colors using rgba(r,g,b,a) instead of rgb(r,g,b). r, g, and b stand for "red", "green", and "blue" respectively, and they represent a value from 0 to 255, specifying the intensity of each hue. The fourth number, a, is known as "alpha" and is the opacity of the color.

Alpha of 1 is fully opaque, and anything less than 1 is like painting with watercolor. Alpha 0 is fully transparent. The special color name transparent stands for rgb(0,0,0,0). Drawing with transparent leaves the canvas perfectly unchanged.

Using pen white is like using opaque white paint: it covers any color with white, but it does not return the canvas to its original transparent state.

The turtle drawing functions support a pseudo-color name called erase. When drawing with pen erase, the canvas is erased of color under the turtle and made transparent again. When using erase, the pen is slightly enlarged so that lines can be cleanly erased without leaving stray pixels.