Random initial color for all Particle Nodes

[RPicster]

In this PR all Particle Nodes get a new parameter: color initial

In this new parameter, a Gradient can be set and each particle will select a random color from that Gradient on birth.
This color then gets multiplied with the overall color. Like this is is combineable with the normal color_ramp (color over life) and color.

This gives a lot more flexibility when setting up particle systems.
It also makes sense to add this as in 4.0 all parameters got min and max values, so it fits into that mindset.

For GPUParticles2D and GPUParticles3D it is solved via the ParticleMaterial class.
For CPUParticles2D and CPUParticles3D it is implemented directly in the classes.

Converting from GPU to CPU is supported in 2D and 3D.

Here are some examples of using this new parameter:

kgY9BrB8tO.mp4

[Calinou]

Now that we have a random initial color ramp, do the Hue Random properties still have an use case? These also provided random color functionality, but in a less flexible way (it was also harder to control).

[RPicster]

Now that we have a random initial color ramp, do the Hue Random properties still have an use case? These also provided random color functionality, but in a less flexible way (it was also harder to control).

I also tought about this, but hue manipulation is doind a different kind of color change than a multiplication.
I agree that hue is pretty hard to use "correctly", but I don't think it is out of use.

Sometimes it's really great to combine all of the properties to get a lot of variety in the final result.

EDIT: A good example of a combination of both parameters:
You want a firework that has a random initial color of either red, blue or yellow.
Now combining that with a random hue those initial colors would be slightly shifted resulting in a more interesting color 👍

[akien-mga]

Thanks!

[RPicster]

If it's ok, I would love to do a backport for 3.x 😃

[akien-mga]

Sure 👍