Allow zsweep to be set in CLI & GUI

[hellocatfood]

(copied over from savbran/evolvotron-fixed#1)

Is there a way to render an animation on the command line but have it play at a constant speed. When I run the following command the animation renders:

evolvotron_render -f 50 --size 512x512 -j output.png < evolvotron_function_1.xml

However, it speeds up and then slows down towards the end.

video.mp4

I'd like it to play at a constant speed.

I've noticed that evolvotron_mutate has the --linear option but using evolvotron_mutuate would change the original function, which is not what I want.

The main evolvotron has the --linear option but it doesn't seem to do anything.

I'm using Evolvotron 0.8.1 and this function file: https://github.com/kmatylla/evolvotron-xml/blob/master/finished%20evolved%20patterns/stained%20windows%201.xml (I've tested it on many functions and still have the same result)

[WickedSmoke]

I've never used the animation options but it looks like they were never really developed much (e.g. there's no controls in the main GUI program).

The evolvotron_render program is pretty basic and seems intended to generate image files, not present them. Some other presentation program would have to be used to control how they are displayed.

[hellocatfood]

The evolvotron_render program is pretty basic and seems intended to generate image files, not present them. Some other presentation program would have to be used to control how they are displayed.

I'm not necessarily asking for evolvotron to handle how the animations are displayed. The readme itself specifies that other programs, such as imagemagick, should be used to handle the output animations/files.

The animations themselves, as rendered by evolvotron, start slowly, speed up, and then slow down. Here's another animation which hopefully demonstrates this better. This was rendered to image frames using the evolvotron gui by running evolvotron -f 300 and then saving one of the images, which saves each frame as a png. Then I used ffmpeg to compile the images to a video

untitled.mp4

so, rather than it speeding up and and then slowing down what I'm requesting is that the animations go at a constant speed

[hellocatfood]

I just had a look at the evolvotron_mutate program and it has the --linear option:

       -l, --linear
            Created functions (if they are rendered as animations) will  sweep
            z linearly (rather than sinusoidally).

This would appear to do what I'm requesting, however it only works if the -g/--genesis option is used (from line 86 on https://github.com/WickedSmoke/evolvotron/blob/master/evolvotron_mutate/evolvotron_mutate.cpp). It doesn't look like it can be used on input .xml functions.

[hellocatfood]

Mastondon user claude very handily pointed out that within the function xml file exists an option to set zsweep to either sinusoidal or linear. By default it is sinusoidal.

Here is the following function rendered with sinusoidal z sweep (default).

evolvotron_function_2.zip

sinusoidal.mp4

And linear.

linear.mp4

He also pointed out where in the code this option is parsed

evolvotron/libevolvotron/mutatable_image.cpp

Lines 314 to 334 in 673aae3

	QStringRef zsweep = atts.value(QString(), "zsweep");
	if (zsweep.isEmpty())
	{
	warning += "Warning: zsweep attribute not found\nDefaulting to sinusoidal\n";
	*_ret_sinusoidal_z=true;
	}
	else
	{
	if (zsweep==QString("sinusoidal"))
	*_ret_sinusoidal_z=true;
	else if (zsweep==QString("linear"))
	*_ret_sinusoidal_z=false;
	else
	{
	QString msg("Error: zsweep attribute expected \"sinusoidal\" or \"linear\", but got \"");
	msg.append(zsweep);
	msg.append("\"\n");
	raiseError(msg);
	return false;
	}
	}

So, whilst the z sweep can be changed in the file itself, this isn't documented anywhere, and I think it would be good to add it as an option during rendering either in the gui or using evolvotron_render

[WickedSmoke]

I understand what you wanted to be constant now. The XML is the specification for what to render, so it seems you have a solution.

If someone wants to submit a tested patch for a --linear option that would be welcome.
It would be good for the GUI to configure Zsweep as well.

Please note that I can't view any of the videos you are posting - my browser says the "file is corrupt". Is it possible to delete them (to not clutter the issue)?

[WickedSmoke]

Should we change the title of this issue to "Allow zsweep to be set in CLI & GUI"?

[hellocatfood]

Yes, good idea.