I think this is the fix: https://github.com/OpenImageIO/oiio/pull/2981
Thanks for alerting me to this bug, Daniel. > On May 27, 2021, at 11:22 PM, Larry Gritz <l...@larrygritz.com> wrote: > > Aha, there does seem to be a bug. The docs say that render_text ought to be > doing an "over", but you are right, it's not behaving that way at all! > > Your understanding of what *should* happen is also how I thought it worked. > It's just a mistake somewhere, I will try to find a fix. > > -- lg > > >> On May 27, 2021, at 12:35 AM, Daniel Flehner Heen <flehnerhee...@gmail.com >> <mailto:flehnerhee...@gmail.com>> wrote: >> >> Hi Larry! >> >> Apologize for the lack of response. >> >> Inspecting the values indeed show variations in the alpha channel, so it >> works and this turns out to be a case of misconception from my side. >> I assumed that render_text would do an "over" and that by setting alpha of >> text color to values below 1 would yield "see through" text rather than >> directly manipulating the pixels in the buffer. >> >> Thank you for your help! >> >> >> >> On Tue, May 25, 2021 at 9:31 PM Larry Gritz <l...@larrygritz.com >> <mailto:l...@larrygritz.com>> wrote: >> Sorry, of course I meant (1+0.6*something). The 0.4 is opacity, not >> transparency. >> >> A over B = A + (1-A.alpha)*B >> >> >>> On May 25, 2021, at 12:30 PM, Larry Gritz <l...@larrygritz.com >>> <mailto:l...@larrygritz.com>> wrote: >>> >>> Well, you have set the text color to (1,1,1,0.4), so if you put that "over" >>> an image, then write to (or display on) a LDR device or file, the resulting >>> "clamp" to the full intensity of the output will not be distinguishable >>> from if it were opaque. But if you are inspecting values in an HDR format >>> like OpenEXR, then the values of text (1,1,1,0.4) over "something" will be >>> (1+0.4*something, ...), whereas opaque (1,1,1,1) over "something" will be >>> exactly (1.0, ...) no matter what the something is. Note that for both of >>> those, if clamped to a max of 1.0, they will look the same. >>> >>> >>>> On May 25, 2021, at 12:18 PM, Daniel Flehner Heen <flehnerhee...@gmail.com >>>> <mailto:flehnerhee...@gmail.com>> wrote: >>>> >>>> Hmmm. I've only checked visually, but when rendering on an image I can't >>>> see through the text. If you get transparency I must be doing something >>>> wrong. >>>> I'm not in front of a computer at the moment, but I'll try and break down >>>> my process and see if I can figure it out. >>>> I'll let you know what I find. >>>> >>>> Thanks, >>>> >>>> >>>> >>>> >>>> >>>> On Tue, May 25, 2021, 21:01 Larry Gritz <l...@larrygritz.com >>>> <mailto:l...@larrygritz.com>> wrote: >>>> Works for me. How are you determining that there is "no difference in >>>> transparency"? Are you inspecting the alpha values in the output file? Are >>>> you compositing on top of something? >>>> >>>> >>>>> On May 25, 2021, at 11:58 AM, Daniel Flehner Heen >>>>> <flehnerhee...@gmail.com <mailto:flehnerhee...@gmail.com>> wrote: >>>>> >>>>> Sorry, should have been more specific. >>>>> There seems to be no difference in the text's transparency for values >>>>> between 0.1 and 1.0 for the alpha channel. >>>>> >>>>> On Tue, May 25, 2021, 20:48 Larry Gritz <l...@larrygritz.com >>>>> <mailto:l...@larrygritz.com>> wrote: >>>>> What happens, specifically? >>>>> >>>>> >>>>>> On May 25, 2021, at 6:31 AM, Daniel Flehner Heen >>>>>> <flehnerhee...@gmail.com <mailto:flehnerhee...@gmail.com>> wrote: >>>>>> >>>>>> Hi! >>>>>> >>>>>> I'm attempting to render text with 40% opacity in python without >>>>>> success. OIIO 2.2.10.1 >>>>>> >>>>>> ``` python >>>>>> import OpenImageIO as oiio >>>>>> buf = oiio.ImageBuf(oiio.ImageSpec(640, 480, 4 oiio.FLOAT)) >>>>>> oiio.ImageBufAlgo.render_text(buf, 100, 200, "Hello, World!", 60, >>>>>> "FreeSans", (1, 1, 1, 0.4)) >>>>>> buf.write('transparent_text_test.exr') >>>>>> ``` >>>>>> >>>>>> Am I doing something wrong? >>>>>> Any pointers would be greatly appreciated. >>>>>> >>>>>> Thanks, >>>>>> >>>>>> -- >>>>>> -Daniel >>>>>> _______________________________________________ >>>>>> Oiio-dev mailing list >>>>>> Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> >>>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>>> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >>>>> >>>>> -- >>>>> Larry Gritz >>>>> l...@larrygritz.com <mailto:l...@larrygritz.com> >>>>> >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> Oiio-dev mailing list >>>>> Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> >>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >>>>> _______________________________________________ >>>>> Oiio-dev mailing list >>>>> Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> >>>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>>> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >>>> >>>> -- >>>> Larry Gritz >>>> l...@larrygritz.com <mailto:l...@larrygritz.com> >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Oiio-dev mailing list >>>> Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> >>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >>>> _______________________________________________ >>>> Oiio-dev mailing list >>>> Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> >>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >>> >>> -- >>> Larry Gritz >>> l...@larrygritz.com <mailto:l...@larrygritz.com> >>> >>> >>> >>> >> >> -- >> Larry Gritz >> l...@larrygritz.com <mailto:l...@larrygritz.com> >> >> >> >> >> _______________________________________________ >> Oiio-dev mailing list >> Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> >> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >> >> >> -- >> -Daniel >> _______________________________________________ >> Oiio-dev mailing list >> Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> >> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org > > -- > Larry Gritz > l...@larrygritz.com <mailto:l...@larrygritz.com> > > > > > _______________________________________________ > Oiio-dev mailing list > Oiio-dev@lists.openimageio.org > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org -- Larry Gritz l...@larrygritz.com
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