readRawByteOutputs(sizePower) {
        return this._renderReadDealloc(WglTexturePool.takeRawByteTex(sizePower));
    }
Renders the result into a float texture, reads the pixels, and returns the result.
This method is slow (because it uses readPixels) and mainly exists for easy testing.
@param {!int} sizePower
@returns {!Uint8Array}