Optimizing FBO's

Newbie & Debugging Questions
#1

Hi,

After using two FBO’s, my frame rate has dropped from the usual vsynch’d 60fps to 30fps. This is the code:


		blurTargetA.bind();
		Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
		batch.setShader(null);

		batch.begin();

		worldMap.drawMap(debug, batch, regions, camX, camY, endX , endY, WORLDWIDTH, WORLDHEIGHT);
				
		batch.flush();
	
		batch.setShader(blurShader);
		// pass 1 - horizontal blur
		blurShader.setUniformf("dir", 1f, 0f);
		blurShader.setUniformf("radius", 1 * MAX_BLUR);

		blurTargetB.bind();

		Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

		fboRegion.setTexture(blurTargetA.getColorBufferTexture());
		
		batch.setColor(1,1,1,1);  // VIP! 

		batch.draw(fboRegion, 0, 0, SCREENWIDTH, SCREENHEIGHT);
		batch.flush();
		FrameBuffer.unbind();

		blurShader.setUniformf("dir", 0f, 1f);
		blurShader.setUniformf("radius", 1 * MAX_BLUR);
		fboRegion.setTexture(blurTargetB.getColorBufferTexture());

		batch.setProjectionMatrix(camera.combined);  // bind to main camera projection - VIP!!!
		
		batch.draw(fboRegion, (camX*16),(camY*16));//, 320,480);draw to position x400,y400
			
		batch.setShader(null);

FBO’s are created in my create method:


			blurTargetA = new FrameBuffer(Format.RGBA8888, SCREENWIDTH, SCREENHEIGHT, false);
			blurTargetB = new FrameBuffer(Format.RGBA8888, SCREENWIDTH, SCREENHEIGHT,  false);
			fboRegion = new TextureRegion(blurTargetA.getColorBufferTexture());
			
			fboRegion.flip(false, true);

Is there any optimizations that could be made to the above although I think it looks ok, if I set the shader to null instead of blurshader, I get the 60fps back, so looking more likely the shader is the cause of it:


varying vec4 vColor;
varying vec2 vTexCoord;

//declare uniforms
uniform sampler2D u_texture;
uniform float resolution;
uniform float radius;
uniform vec2 dir;

void main() {
    //this will be our RGBA sum
    vec4 sum = vec4(0.0);

    //our original texcoord for this fragment
    vec2 tc = vTexCoord;

    //the amount to blur, i.e. how far off center to sample from 
    //1.0 -> blur by one pixel
    //2.0 -> blur by two pixels, etc.
    float blur = radius/resolution; 

    //the direction of our blur
    //(1.0, 0.0) -> x-axis blur
    //(0.0, 1.0) -> y-axis blur
    float hstep = dir.x;
    float vstep = dir.y;

    //apply blurring, using a 9-tap filter with predefined gaussian weights

    sum += texture2D(u_texture, vec2(tc.x - 4.0*blur*hstep, tc.y - 4.0*blur*vstep)) * 0.0162162162;
    sum += texture2D(u_texture, vec2(tc.x - 3.0*blur*hstep, tc.y - 3.0*blur*vstep)) * 0.0540540541;
    sum += texture2D(u_texture, vec2(tc.x - 2.0*blur*hstep, tc.y - 2.0*blur*vstep)) * 0.1216216216;
    sum += texture2D(u_texture, vec2(tc.x - 1.0*blur*hstep, tc.y - 1.0*blur*vstep)) * 0.1945945946;

    sum += texture2D(u_texture, vec2(tc.x, tc.y)) * 0.2270270270;

    sum += texture2D(u_texture, vec2(tc.x + 1.0*blur*hstep, tc.y + 1.0*blur*vstep)) * 0.1945945946;
    sum += texture2D(u_texture, vec2(tc.x + 2.0*blur*hstep, tc.y + 2.0*blur*vstep)) * 0.1216216216;
    sum += texture2D(u_texture, vec2(tc.x + 3.0*blur*hstep, tc.y + 3.0*blur*vstep)) * 0.0540540541;
    sum += texture2D(u_texture, vec2(tc.x + 4.0*blur*hstep, tc.y + 4.0*blur*vstep)) * 0.0162162162;

    //discard alpha for our simple demo, multiply by vertex color and return
    //gl_FragColor = vColor * vec4(sum.rgb, 1);
    vec4 texColor = texture2D(u_texture, vTexCoord);
    
    gl_FragColor = vColor * vec4(sum.rgb, texColor.a);
}

Appreciate any advice. Maybe sampling to half screen width and height? Possibly pass texture chords into vertex shader so no real computing in frag shader…

Thanks

PS - the 30fps is on my laptop which has a crap intel hd4000 GPU.