List of nodes

[PavelBlend]

I decided to write a list of nodes that can be implemented. If you have questions or suggestions, then write your opinion. I decided to write this list now so that it would not come as a surprise to the architecture of the physical engine. It’s better to understand in advance what needs to be realized than to rebuild the architecture in the future.

Converter Nodes
    Math
        An analogue of the standard Math node. Two numbers can be input
        (int/float), and the result is the result of sums, differences,
        products ...

    Vector Math
        An analog of the Math node, but for vectors.

    Color Mix
        For mixing two colors. Blend Modes: MIX, MULTIPLY, LIGHTEN, ADD...

    Boolean Math
        Logic math. Has two bool inputs. Modes: and, or, not...

    Separate RGB
        Decomposition of color into components (red, green, blue).

    Separate HSV
        Decomposition of color into components (hue, saturation, value).

    Combine RGB
        Combine the individual components of R, G, and B in color.

    Combine HSV
        Combine the individual components of H, S, and V in color.

    Color Ramp
        The standard blender node. Need to change color. To create gradients,
        increase contrast, etc.


Texture Nodes
    Gradient
    Noise
    Voronoi

Structure Nodes
    Make List
    Merge Lists

Time Nodes
    Time Info
        Has Params: scene start time, end time, current time

    Frame Info
        Has Params: scene start frame, end frame, current frame

    Time Speed Info
        Has Params: FPS, Time Factor (Simulation slowdown or acceleration rate)

Simulation Objects Nodes
    Emitter
    Collider
    Outflow
    Hub
    Simulation
    World
        params: use_world_scaling, world_size (meters), close_boundary,
        boundary_friction

Input Nodes
    Integer
    Float
    Integer Vector
    Float Vector
    Boolean
    Boolean Vector
    Color RGB
    Color RGBA
    Transforms
        Has inputs: bpy_object, has outputs: location, rotation, scale, dimensions...

Effects Nodes
    Viscosity
    Surface Tension
    Vorticity
    Elasticity

Source Nodes
    Mesh Object
    Curve Object

Force Nodes
    Gravity
    Force
    Wind
    Vortex
    Noise
    Curve

Generator Nodes
    Mesh Generator
    Particle System Converter

Output Nodes
    Disk Cache

[yuanming-hu]

The list in general looks very nice to me. A few quick questions before I come up with more:

• Do Blender nodes support multiple inputs? something like
  

• Do we have to implement the Texture nodes on our own? That sounds a lot of work and maybe we should consider borrowing some nodes from other Blender node graph systems.

• In my understanding Emitter generates particles just once, and Source continuously generates particles, is that correct?

[PavelBlend]

• Do Blender nodes support multiple inputs? something like

The blender does not support many inputs. Only one.

• Do we have to implement the Texture nodes on our own? That sounds a lot of work and maybe we should consider borrowing some nodes from other Blender node graph systems.

I haven't figured it out yet. But I have never seen a standard node in any addon.

• In my understanding Emitter generates particles just once, and Source continuously generates particles, is that correct?

I do not know all the intricacies of physical simulators. Not sure how things should be.

[yuanming-hu]

I do not know all the intricacies of physical simulators. Not sure how things should be.

I think we can simply use a "source" node, and add an "outflow" option

• Outflow = False means the emitter will create a bunch of particles at a certain time
• Outflow = True means the emitter will continuously generate particles

To be honest I don't have too much knowledge of the UI of physical simulators either - Maybe we can just deliver an experimental version and gather some feedbacks from the users.

[PavelBlend]

• Do we have to implement the Texture nodes on our own? That sounds a lot of work and maybe we should consider borrowing some nodes from other Blender node graph systems.

I searched a bit for information. It seems that you cannot create and duplicate nodes from the standard part of the blender. For example, the ColorRamp node:

https://blender.stackexchange.com/questions/19289/are-ui-color-ramps-possible-through-python

[yuanming-hu]

I looked into the three node-systems you posted, and it indeed seems to me that they are all recreating their own nodes over and over again. E.g. https://github.com/hsab/GrowthNodes/tree/master/umog_addon/nodes/integer

I also checked the Blender source code, and it seems to me that the Texture nodes are implemented in C++, e.g. https://github.com/sobotka/blender/blob/master/intern/cycles/render/nodes.cpp#L1008

It seems to me that the Blender components each have an independent node system.

One more possibility to reduce the burden on our side: can we somehow import a texture from another node system? For example, is there a "texturing" node graph system that can generate a procedural texture, and we can simply take the output as a texture map for simulation, e.g. for varying particle stiffness/viscosity?

[PavelBlend]

You can create a texture in bpy.data.textures. Then you can find out the value of the texture using the evaluate function. But I do not know what to do with the ColorRamp node.

[yuanming-hu]

I see. That sounds like a good way to offload the 2D/3D textures/volumes.
For the ColorRamp node, if that's relatively simple to implement, maybe we can implement it on our own. (Evaluating a color per particle is not too much computation and python/numpy should be able to handle it well, if I understand everything correctly.)

[K0K0ze]

• Do Blender nodes support multiple inputs? something like

The blender does not support many inputs. Only one.

The join node in geometry nodes got updated and joined the input sockets. Maybe when Blender 3.0 is out of Beta the new type could be added?

In 2.93 it was seperated
In 3.0 it is joined