public void setPixel(int x, int y, int face, ColorRGBA color) {
        raster.setSlice(face);
        raster.setPixel(x, y, color);
    }
Writes a pixel given the 2-D coordinates and the color
@param x the x tex coord (from 0 to width)
@param y the y tex coord (from 0 to height)
@param face the face to write to
@param color the color to write
jme3-core/src/main/java/com/jme3/environment/util/CubeMapWrapper.java