Histogram Keyer Node Bug

[blackearth2014]

Hello Fabien

I had downloaded the new tuttle binaries for the mac. The attached images is a result of that new download. I don't even have the Histogram Keyer Node attached and it has taking focus of the Natron's viewer output.

Best regards,
Omar

[fabiencastan]

See MrKepzie/Natron#223

[devernay]

Found one bug in TuttleHistogramKeyer. The function HistogramKeyerOverlay::displaySelectedAreas() does not enable blending. By chance, Nuke enables it, but other hosts (e.g. Natron) do not.
The function should start with:

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

and end with:

glDisable(GL_BLEND);

[devernay]

Another bug:
TuttleHistogramKeyer should call Interact::addParamToSlaveTo(Param* p) for all params that affect the overlay display (i.e. most of the parameters...)

[devernay]

Another bug: TuttleHistogramKeyer claims it supports OFX::ePixelComponentRGB, but the red, green, blue histograms are wrong. They are probably computed by considering the image data as RGBA, which results is almost equal red, green and blue curves (colors are mixed).
Nuke doesn't support RGB, but this can be tested easily using Natron.

[devernay]

TuttleHistogramKeyer also calls OfxParametricInstance::addControlPoint with NaN values (this used to crash Natron, but we are now robust against this)