@Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        String mrtStr = colorBufIndex >= 0 ? "" + colorBufIndex : "mrt";
        sb.append("FrameBuffer[format=").append(width).append("x").append(height)
                .append("x").append(samples).append(", drawBuf=").append(mrtStr).append("]\n");
        if (depthBuf != null) {
            sb.append("Depth => ").append(depthBuf).append("\n");
        }
        for (RenderBuffer colorBuf : colorBufs) {
            sb.append("Color(").append(colorBuf.slot)
                    .append(") => ").append(colorBuf).append("\n");
        }
        return sb.toString();
    }
@return The number of samples when using a multisample framebuffer, or
1 if this is a single-sampled framebuffer.
jme3-core/src/main/java/com/jme3/texture/FrameBuffer.java