TwoPassFilter.java

package com.marshalchen.common.uimodule.imageprocessing.filter;

import android.opengl.GLES20;

/**
 * An extension of BasicFilter. This class allows for a filter program to be applied twice to a given input.
 * The same fragment and vertex shaders will be used for both of the passes. Also the same values will be passed
 * for both passes unless specifically changed.  To check which pass is currently being run during passShaderValues(),
 * getCurrentPass() can be called.  The current pass will either be 1 or 2.
 * @author Chris Batt
 */
public abstract class TwoPassFilter extends BasicFilter {
	private int[] firstPassFrameBuffer;
	private int[] firstPassTextureOut;
	private int[] firstPassDepthRenderBuffer;
	
	private int currentPass;
	
	/* (non-Javadoc)
	 * @see com.marshalchen.common.uimodule.imageprocessing.input.GLTextureOutputRenderer#destroy()
	 */
	@Override
	public void destroy() {
		super.destroy();
		if(firstPassFrameBuffer != null) {
			GLES20.glDeleteFramebuffers(1, firstPassFrameBuffer, 0);
			firstPassFrameBuffer = null;
		}
		if(firstPassTextureOut != null) {
			GLES20.glDeleteTextures(1, firstPassTextureOut, 0);
			firstPassTextureOut = null;
		}
		if(firstPassDepthRenderBuffer != null) {
			GLES20.glDeleteRenderbuffers(1, firstPassDepthRenderBuffer, 0);
			firstPassDepthRenderBuffer = null;
		}
	}
	
	
	@Override
	protected void drawFrame() {
		currentPass = 1;
		if(firstPassFrameBuffer == null) {
			if(getWidth() != 0 && getHeight() != 0) {
				initFBO();
			} else {
				return;
			}
		}

		GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, firstPassFrameBuffer[0]);
		
		if(texture_in == 0) {
			return;
		}
		
		GLES20.glViewport(0, 0, getWidth(), getHeight());
        GLES20.glUseProgram(programHandle);

		GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
		GLES20.glClearColor(getBackgroundRed(), getBackgroundGreen(), getBackgroundBlue(), getBackgroundAlpha());
		
		passShaderValues();
		
		GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4); 
		
		texture_in = firstPassTextureOut[0];
		
		GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
		
		currentPass = 2;
		super.drawFrame();
	}
	
	protected int getCurrentPass() {
		return currentPass;
	}
	
	private void initFBO() {
		if(firstPassFrameBuffer != null) {
			GLES20.glDeleteFramebuffers(1, firstPassFrameBuffer, 0);
			firstPassFrameBuffer = null;
		}
		if(firstPassTextureOut != null) {
			GLES20.glDeleteTextures(1, firstPassTextureOut, 0);
			firstPassTextureOut = null;
		}
		if(firstPassDepthRenderBuffer != null) {
			GLES20.glDeleteRenderbuffers(1, firstPassDepthRenderBuffer, 0);
			firstPassDepthRenderBuffer = null;
		}
		firstPassFrameBuffer = new int[1];
		firstPassTextureOut = new int[1];
		firstPassDepthRenderBuffer = new int[1];
		GLES20.glGenFramebuffers(1, firstPassFrameBuffer, 0);
		GLES20.glGenRenderbuffers(1, firstPassDepthRenderBuffer, 0);
		GLES20.glGenTextures(1, firstPassTextureOut, 0);
		
		GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, firstPassFrameBuffer[0]);
		
		GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
		GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, firstPassTextureOut[0]);
		GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGB, getWidth(), getHeight(), 0, GLES20.GL_RGB, GLES20.GL_UNSIGNED_SHORT_5_6_5, null);
		GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
		GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
		GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
		GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
		GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_TEXTURE_2D, firstPassTextureOut[0], 0);
		
		GLES20.glBindRenderbuffer(GLES20.GL_RENDERBUFFER, firstPassDepthRenderBuffer[0]);
		GLES20.glRenderbufferStorage(GLES20.GL_RENDERBUFFER, GLES20.GL_DEPTH_COMPONENT16, getWidth(), getHeight());
		GLES20.glFramebufferRenderbuffer(GLES20.GL_FRAMEBUFFER, GLES20.GL_DEPTH_ATTACHMENT, GLES20.GL_RENDERBUFFER, firstPassDepthRenderBuffer[0]);
		
		int status = GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER);
		if (status != GLES20.GL_FRAMEBUFFER_COMPLETE) {
			throw new RuntimeException(this+": Failed to set up render buffer with status "+status+" and error "+GLES20.glGetError());
		}
	}
}