Fbo blending issue

beginners
#1

Hello,

I’m trying to figure out an issue with an FBO.
Basically I have something that draws a glowing sphere. It works OK until I wrap an fbo around it.
If I try to draw the fbo it looses… parts of what it’s wrapping around.

the good:

good.png1581×1197 125 KB

the bad:

bad.png1593×1197 109 KB

and then some code that I’m wrapping into the fbo:

ofClear(255, 255, 255, 0); ofBackground(0,0,0); glEnable(GL_CULL_FACE); camera.begin(); ofEnableBlendMode(OF_BLENDMODE_ALPHA); gradientBackground(); glEnable(GL_DEPTH_TEST); glDepthMask(true); solidSphere(); glDisable(GL_DEPTH_TEST); ofDisableBlendMode(); ofEnableBlendMode(OF_BLENDMODE_ADD); glow01(); glow02(); glow03(); ofDisableBlendMode(); ofEnableBlendMode(OF_BLENDMODE_ALPHA); camera.end(); gui.draw(); ofDrawBitmapString(ofToString(ofGetFrameRate());

Not even the gui is showing in case of the FBO, I just see a thin outline. Perhaps that’s a clue…
The parts that are not showing up are planes with a shader. Other pieces, like a sphere and sprites (also with shaders) are showing up.

#2

weird… what I’ve done is this,
rotated the plane with the background gradient and the glowing ring 180 degrees in the setup.
plane.rotate(180, 1.0, 0.0, 0.0);
This shows the glow around the orb, but… the central sphere is nowhere to be seen. I really think this has something to do with alpha.

#3

Can you post the rest of your code on here to check out?

How are you initializing the FBO?

#4

ofFbo::Settings s; s.width = ofGetWindowWidth(); s.height = ofGetWindowHeight(); s.internalformat = GL_RGBA32F_ARB; fbo.allocate(s); fbo.begin(); ofClear(0, 0, 0, 0); fbo.end();

right now in the draw I have:
fbo.begin(); visionFilter(); fbo.end(); fbo.draw(0, 0);

the functions in the fbo are basically shaders drawing spheres, planes and sprites.
if I comment fbo.begin and fbo.end everything draws correctly.

#5

Another thing that works is disabling the camera in the fbo. which then requires me to push/pop/translate the visionFilter during the begin/end of the fbo, but that’s a solution, since I don’t really need to rotate anything. The camera was a leftover from an older version.