VertexBuffer Example

float h = 5.0F;
		float radius = 50.0F;
		int segments = 4;
		int subsegments = 8;
		float subsegmentAngle;

		Tessellator tess = Tessellator.getInstance();
		VertexBuffer vtxBuf = tess.getBuffer();
		GlStateManager.pushMatrix();
		GlStateManager.pushAttrib();
		GlStateManager.disableTexture2D();
		GlStateManager.enableBlend();
		GlStateManager.blendFunc(SourceFactor.SRC_ALPHA, DestFactor.SRC_ALPHA);
		GlStateManager.color(0, 128, 128);
		GlStateManager.translate(x, y, 0.0F);
		subsegmentAngle = (float) (2 * Math.toDegrees(Math.asin(h / radius)));
		if(subsegments % 2 == 0) GlStateManager.rotate(0.5F * subsegmentAngle, 0.0F, 0.0F, 1.0F);
		for(int segment = 0; segment < segments; segment++)
		{
			GlStateManager.rotate(360 / segments, 0.0F, 0.0F, 1.0F);
			GlStateManager.pushMatrix();
			GlStateManager.translate(SEGMENT_OFFSET, 0.0F, 0.0F);
			GlStateManager.rotate(-(subsegments / 2) * subsegmentAngle, 0.0F, 0.0F, 1.0F);
			for(int subsegment = 0; subsegment < subsegments; subsegment++)
			{
				vtxBuf.begin(GL11.GL_TRIANGLE_FAN, DefaultVertexFormats.POSITION);
				vtxBuf.pos(0, 0, 0).endVertex();
				vtxBuf.pos(radius, h, 0).endVertex();
				vtxBuf.pos(radius, -h, 0).endVertex();
				tess.draw();
				GlStateManager.rotate(subsegmentAngle, 0.0F, 0.0F, 1.0F);
			}

			GlStateManager.popMatrix();
		}
		GlStateManager.popAttrib();
		GlStateManager.popMatrix();