Nodes backend inconsistency overview #120855

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Iliya Katushenock · 2024-04-20T17:09:44+02:00

Iliya Katushenock commented

2024-04-20 17:09:44 +02:00

This is overview of different built-in nodes editor backends that are inconsistent in cases that are shared between of them.
This is general behavior, not engine-related one.

Source of value

Source of value is the socket. So, if user can see value on the scene then this value is in some certain socket or result of computations that is based on such socket value.
Only one exception here is Reroute node. This is source less socket.
Value of the socket can be non trivial. Examples:

Implicit field inputs in geometry nodes.
Automatic UV input in shader texture nodes.

But value have to be.

General rules for consistency:

Muted node:
Muted node still have sockets and this sockets still have its values. This values have to be accessible via internal links.
Dangling Reroute:
If branch of reroute nodes is not connected to any source of the value, this branch have no any effect on the target socket.
Group Interface:
Group interface corresponding additional set of sockets in external/internal node tree and this values have to take into account.

Current issues in behavior of the node editors:

Cycles ignore socket value of muted node and retrieve zero.
Compositor and Eevee ignore mute node and retrieve latest socket of non-muted node.
Cycles doesn't ignore dangling reroutes.

Implicit type conversion

Type conversion is based on the socket types. If socket is there and link is connected, value should be converted.
No matter what the state of the node is. Socket have to perform type conversion on the value in any case.
This is visibly pointed by the link style between sockets.

Current issues in behavior of the node editors:

Compositor and Eevee skip type conversion in case of through link of node group and muted node.
Cycles skip conversion for input socket of node group.

Rainbow link

If link is colored by unusual color, this is not the link.

Muted link:
This link is intentionally muted by used, so user can change default value of socket for fast check.
Invalid link.
There is no implicit type cast between sockets of the link. Value should be such so user will want to fix this. So this is one exception where value can be zero. This is invalid case and user should fix this, instead of keep have this.

Current issues in behavior of the node editors:

Geometry Nodes do not produce zero result for invalid links.

This is overview of different built-in nodes editor backends that are inconsistent in cases that are shared between of them. This is general behavior, not engine-related one. ### Source of value Source of value is the socket. So, if user can see value on the scene then this value is in some certain socket or result of computations that is based on such socket value. Only one exception here is Reroute node. This is source less socket. Value of the socket can be non trivial. Examples: 1. Implicit field inputs in geometry nodes. 2. Automatic UV input in shader texture nodes. But value have to be. General rules for consistency: 1. Muted node: Muted node still have sockets and this sockets still have its values. This values have to be accessible via internal links. 2. Dangling Reroute: If branch of reroute nodes is not connected to any source of the value, this branch have no any effect on the target socket. 3. Group Interface: Group interface corresponding additional set of sockets in external/internal node tree and this values have to take into account. Current issues in behavior of the node editors: 1. Cycles ignore socket value of muted node and retrieve zero. 2. Compositor and Eevee ignore mute node and retrieve latest socket of non-muted node. 3. Cycles doesn't ignore dangling reroutes. ### Implicit type conversion Type conversion is based on the socket types. If socket is there and link is connected, value should be converted. No matter what the state of the node is. Socket have to perform type conversion on the value in any case. This is visibly pointed by the link style between sockets. Current issues in behavior of the node editors: 1. Compositor and Eevee skip type conversion in case of through link of node group and muted node. 2. Cycles skip conversion for input socket of node group. ### Rainbow link If link is colored by unusual color, this is not the link. 1. Muted link: This link is intentionally muted by used, so user can change default value of socket for fast check. 2. Invalid link. There is no implicit type cast between sockets of the link. Value should be such so user will want to fix this. So this is one exception where value can be zero. This is invalid case and user should fix this, instead of keep have this. Current issues in behavior of the node editors: 1. Geometry Nodes do not produce zero result for invalid links.

Iliya Katushenock added the

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Design

label 2024-04-20 17:09:44 +02:00

Iliya Katushenock self-assigned this 2024-04-20 17:09:45 +02:00

Iliya Katushenock added this to the Nodes & Physics project 2024-04-20 17:09:45 +02:00

Iliya Katushenock referenced this issue

2024-04-20 17:10:48 +02:00

Nodes: Compositor and Eevee renders skip implicit type conversions in some cases #54777

Iliya Katushenock added the