Use this in your slot renderer file.
@Override
public void renderSlot(int index, int x, int y, float slotHeight, Tessellator tessellator)
{
tessellator.startDrawingQuads();
tessellator.addVertexWithUV(x - slotHeight / 2 * 1.3, y + slotHeight / 2 * 1.3, -90.0D, 0.35D...