public void setMultiTarget(boolean enabled) {
        if (enabled) {
            colorBufIndex = -1;
        } else {
            colorBufIndex = 0;
        }
    }
If enabled, any shaders rendering into this <code>FrameBuffer</code>
will be able to write several results into the renderbuffers
by using the <code>gl_FragData</code> array. Every slot in that
array maps into a color buffer attached to this framebuffer.

@param enabled True to enable MRT (multiple rendering targets).
jme3-core/src/main/java/com/jme3/texture/FrameBuffer.java