code: func (c *RGBA) SetColors(r, g, b, a float64) {
  	c.rgba.red = C.gdouble(r)
  	c.rgba.green = C.gdouble(g)
  	c.rgba.blue = C.gdouble(b)
  	c.rgba.alpha = C.gdouble(a)
  }
docs: // SetColors sets all colors values in the RGBA.