NativeBufferPool.java

package org.oscim.renderer;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.IntBuffer;
import java.nio.ShortBuffer;

import org.oscim.renderer.NativeBufferPool.BufferItem;
import org.oscim.utils.pool.Inlist;
import org.oscim.utils.pool.Pool;

/**
 * Pool to retrieve temporary native buffer on GL-Thread:
 * This pool ensures to not use the same buffer to upload data twice
 * within a frame.
 * - Contrary to what the OpenGL doc says data seems *not* to be
 * always* copied after glBufferData returns...
 * - Somehow it does always copy when using Android GL bindings
 * but not when using libgdx bindings (LWJGL or AndroidGL20)
 */
public class NativeBufferPool extends Pool<BufferItem> {

	static final class BufferItem extends Inlist<BufferItem> {
		ByteBuffer byteBuffer;
		ShortBuffer sBuffer;
		FloatBuffer fBuffer;
		IntBuffer iBuffer;

		int size;

		void growBuffer(int size) {
			//log.debug("grow buffer " + size);
			// 32kb min size
			if (size < (1 << 15))
				size = (1 << 15);

			byteBuffer = ByteBuffer
			    .allocateDirect(size)
			    .order(ByteOrder.nativeOrder());
			this.size = size;

			sBuffer = null;
			iBuffer = null;
			fBuffer = null;
		}
	}

	private BufferItem mUsedBuffers;

	@Override
	protected BufferItem createItem() {
		// unused;
		return null;
	}

	public BufferItem get(int size) {
		BufferItem b = mPool;

		if (b == null) {
			b = new BufferItem();
		} else {
			mPool = b.next;
			b.next = null;
		}
		if (b.size < size)
			b.growBuffer(size);

		mUsedBuffers = Inlist.push(mUsedBuffers, b);

		return b;
	}

	public void releaseBuffers() {
		mUsedBuffers = releaseAll(mUsedBuffers);
	}

	/**
	 * Only use on GL Thread! Get a native ShortBuffer for temporary use.
	 */
	public ShortBuffer getShortBuffer(int size) {
		BufferItem b = get(size * 2);

		if (b.sBuffer == null) {
			b.byteBuffer.clear();
			b.sBuffer = b.byteBuffer.asShortBuffer();
		} else {
			b.sBuffer.clear();
		}
		return b.sBuffer;
	}

	/**
	 * Only use on GL Thread! Get a native FloatBuffer for temporary use.
	 */
	public FloatBuffer getFloatBuffer(int size) {
		BufferItem b = get(size * 4);
		if (b.fBuffer == null) {
			b.byteBuffer.clear();
			b.fBuffer = b.byteBuffer.asFloatBuffer();
		} else {
			b.fBuffer.clear();
		}
		b.fBuffer.clear();

		return b.fBuffer;
	}

	/**
	 * Only use on GL Thread! Get a native IntBuffer for temporary use.
	 */
	public IntBuffer getIntBuffer(int size) {
		BufferItem b = get(size * 4);
		if (b.iBuffer == null) {
			b.byteBuffer.clear();
			b.iBuffer = b.byteBuffer.asIntBuffer();
		} else {
			b.iBuffer.clear();
		}
		return b.iBuffer;
	}

}