Capture part of FBO to texture

beginners
#1

Another somewhat simple question.
I have a fbo and I need to capture a rectangular section from it and save it into a texture.
(sort of crop). So I have x,y, width and height (corresponds to ofTexture allocation). What would be the best way to do it ?

Something similar to loadScreenData, but that takes fbo as a source ?

Thanks
M

#2

ofFbo has a texture inside of it –

myFbo.getTexture()

also ofTexture has a “drawSubsection” function which takes a drawing position and texture position, so you could combine them with

myFbo.getTexture().drawSubsection(....)

#3

If you want to save it to an image, you can also use ofFbo.readToPixels and pass in an ofImage, either directly or .getPixels() I forget. I think u might need to call .update on the ofImage after as well.

#4

Hmm
I’ve discovered both, but not sure how to combine them actually.
I need transfer part of fbo (or it’s texture) to another texture (not fbo).
Since I can’t draw on texture, I’m not sure how drawSubsection() can be used in this case…

#5

but readToPixels() seems to ready everything, not just a cropped section… right ?

#6

Could draw to the dst texture and just use a quad mesh with the texcoords you want or a cropped viewport?

#7

Fbos can have multiple textures or use another fbo, so you can render to texture with that.

#8

yeah, thanks.
I ended up using fBO as suggested… I write using draw and supplying x,y offset and then get texture from it.