float alpha = 0.5F;
int x1 = x + drawAreaSizeX;
int y1 = y + drawAreaSizeY;
GlStateManager.enableBlend();
GlStateManager.enableAlpha();
GlStateManager.disableTexture2D();
GlStateManager.color(0, 0, 0, alpha);
Tessellator tessellator = Tessellator.getInstance();
BufferBuilder bufferBuilder = tessellator.getBuffer();
bufferBuilder.begin(GL11.GL_QUADS, DefaultVertexFormats.POSITION_TEX);
bufferBuilder.pos(x, y1, 0).color(0, 0, 0, alpha).endVertex();
bufferBuilder.pos(x1, y1, 0).color(0, 0, 0, alpha).endVertex();
bufferBuilder.pos(x1, y, 0).color(0, 0, 0, alpha).endVertex();
bufferBuilder.pos(x, y, 0).color(0, 0, 0, alpha).endVertex();
tessellator.draw();
GlStateManager.enableTexture2D();
GlStateManager.disableBlend();
GlStateManager.disableAlpha();