buffer.begin(GL11.GL_QUADS, DefaultVertexFormat.POSITION_COLOR);
buffer.pos(x, y, 0).color(color1).endVertex();
buffer.pos(x, y + height, 0).color(color2).endVertex();
buffer.pos(x + width, y + height, 0).color(color3).endVertex();
buffer.pos(x + width, y, 0).color(color4).endVertex();
tessellator.draw();