/**
 * @author liulihaocai
 */
class GuiRiseBackground : GuiScreen() {
    override fun initGui() {
        val bufferedImage = ImageIO.read(GuiRiseBackground::class.java.classLoader.getResourceAsStream("assets/minecraft/fdpclient/misc/bg.png"))
        mc.textureManager.loadTexture(ResourceLocation("NMSL"), DynamicTexture(bufferedImage))
    }

    override fun drawBackground(tint: Int) {
        GL11.glDisable(GL11.GL_DEPTH_TEST)
        GL11.glEnable(GL11.GL_BLEND)
        GL11.glDepthMask(false)
        OpenGlHelper.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA, GL11.GL_ONE, GL11.GL_ZERO)
        RenderUtils.glColor(hslRainbow(1))
        mc.textureManager.bindTexture(ResourceLocation("NMSL"))
        drawModalRectWithCustomSizedTexture(0, 0, 0f, 0f, width, height, width.toFloat(), height.toFloat())
        GL11.glDepthMask(true)
        GL11.glDisable(GL11.GL_BLEND)
        GL11.glEnable(GL11.GL_DEPTH_TEST)
    }

    override fun drawScreen(mouseX: Int, mouseY: Int, partialTicks: Float) {
        drawBackground(-1)
    }

    private val startTime=System.currentTimeMillis()

    fun hslRainbow(index: Int,lowest: Float=0.41f,bigest: Float=0.58f,indexOffset: Int=300,timeSplit: Int=5000): Color {
        return Color.getHSBColor((abs(((((System.currentTimeMillis()-startTime).toInt()+index*indexOffset)/timeSplit.toFloat())%2)-1) *(bigest-lowest))+lowest,0.7f,1f)
    }
}

and dont forgot to put the image

idk how 2 add a blur effect, plz add blur if u can :3