TextureStreamPBO.java

/*
 * Copyright (c) 2002-2012 LWJGL Project
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 * * Redistributions in binary form must reproduce the above copyright
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 *   its contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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package org.lwjgl.util.stream;

import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.opengl.GL12.*;
import static org.lwjgl.opengl.GL15.*;
import static org.lwjgl.opengl.GL21.*;

/** Implements streaming PBO updates to an OpenGL texture. */
abstract class TextureStreamPBO extends StreamBufferedPBO implements TextureStream {

	private final int texID;

	private long currentIndex;

	private boolean resetTexture;

	protected TextureStreamPBO(final StreamHandler handler, final int transfersToBuffer) {
		super(handler, transfersToBuffer);

		texID = glGenTextures();
		glBindTexture(GL_TEXTURE_2D, texID);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glBindTexture(GL_TEXTURE_2D, 0);
	}

	public StreamHandler getHandler() {
		return handler;
	}

	public int getWidth() {
		return width;
	}

	public int getHeight() {
		return height;
	}

	private void resize(final int width, final int height) {
		if ( width < 0 || height < 0 )
			throw new IllegalArgumentException("Invalid dimensions: " + width + " x " + height);

		destroyObjects();

		this.width = width;
		this.height = height;

		this.stride = StreamUtil.getStride(width);

		if ( width == 0 || height == 0 )
			return;

		bufferIndex = 0;
		currentIndex = 0;

		resetTexture = true;

		// Setup upload buffers

		resizeBuffers(height, stride);
	}

	protected void resizeBuffers(final int height, final int stride) {
		super.resizeBuffers(height, stride, GL_PIXEL_UNPACK_BUFFER, GL_STREAM_DRAW);
	}

	public void snapshot() {
		if ( width != handler.getWidth() || height != handler.getHeight() )
			resize(handler.getWidth(), handler.getHeight());

		if ( width == 0 || height == 0 )
			return;

		final int trgPBO = (int)(bufferIndex % transfersToBuffer);

		// Back-pressure. Make sure we never buffer more than <transfersToBuffer> frames ahead.

		if ( processingState.get(trgPBO) )
			syncUpload(trgPBO);

		pinBuffer(trgPBO);

		// Send the buffer for processing

		processingState.set(trgPBO, true);
		semaphores[trgPBO].acquireUninterruptibly();

		handler.process(
			width, height,
			pinnedBuffers[trgPBO],
			stride,
			semaphores[trgPBO]
		);

		bufferIndex++;

		if ( resetTexture ) // Synchronize to show the first frame immediately
			syncUpload(trgPBO);
	}

	protected abstract void pinBuffer(final int index);

	public void tick() {
		final int srcPBO = (int)(currentIndex % transfersToBuffer);
		if ( !processingState.get(srcPBO) )
			return;

		syncUpload(srcPBO);
	}

	private void syncUpload(final int index) {
		glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbos[index]);
		waitForProcessingToComplete(index);

		upload(index);

		glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
	}

	private void upload(final int srcPBO) {
		// Asynchronously upload current update

		glBindTexture(GL_TEXTURE_2D, texID);
		glPixelStorei(GL_UNPACK_ROW_LENGTH, stride >> 2);
		if ( resetTexture ) {
			glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, 0);
			resetTexture = false;
		} else
			glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, 0);
		glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
		glBindTexture(GL_TEXTURE_2D, 0);

		postUpload(srcPBO);

		currentIndex++;
	}

	protected abstract void postUpload(int index);

	public void bind() {
		glBindTexture(GL_TEXTURE_2D, texID);
	}

	protected void destroyObjects() {
		for ( int i = 0; i < semaphores.length; i++ ) {
			if ( processingState.get(i) ) {
				glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbos[i]);
				waitForProcessingToComplete(i);
			}
		}

		glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);

		for ( int i = 0; i < pbos.length; i++ ) {
			if ( pbos[i] != 0 )
				glDeleteBuffers(pbos[i]);
		}
	}

	public void destroy() {
		destroyObjects();
	}

}