Geometry Nodes: new Axis to Euler node #104416

This adds a new Axis to Euler node which creates a new rotation. In many cases, the primary and secondary axis inputs are a normal and tangent of a mesh or curve. This provides a simpler and more direct way to create this rotation compared to using two Align Euler to Vector nodes.

This more direct way of computing the rotation also allows us to optimize the case better. The benchmark file below shows that this new method takes about a third of the time (46ms vs 16ms). Just for the curious, if the node were to output a quaternion instead of an (e.g. once we have a proper rotation socket or optimize the case separately), the time would drop to just 5ms.

This adds a new `Axis to Euler` node which creates a new rotation. In many cases, the primary and secondary axis inputs are a normal and tangent of a mesh or curve. This provides a simpler and more direct way to create this rotation compared to using two `Align Euler to Vector` nodes. ![image](/attachments/88b744eb-47de-4b28-a5f2-f50d4165bb6a) This more direct way of computing the rotation also allows us to optimize the case better. The benchmark file below shows that this new method takes about a third of the time (46ms vs 16ms). Just for the curious, if the node were to output a quaternion instead of an (e.g. once we have a proper rotation socket or optimize the case separately), the time would drop to just 5ms. ![image](/attachments/96efdd4e-c888-410d-8968-1fdadd8d8caa)

image.png

15 KiB

image.png

106 KiB

axis_to_euler_performance.blend

878 KiB

The code looks relatively straightforward. Assuming this works for Simon, this looks good to go.

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Seems good to me overall I tested some corner cases, where I think the behaviour could be different.

When primary and secondary axis are parallel, it should probably ignore the secondary axis entirely. At least I don't see a reason, why it would have any particular impact.

When using only the secondary axis as an input it would make sense to me to rotate first around what is selected as primary axis. Right now it seems a bit random to me, not sure of the logic behind it right now.

e.g. this shouldn't result in any rotation imo

Seems good to me overall I tested some corner cases, where I think the behaviour could be different. When primary and secondary axis are parallel, it should probably ignore the secondary axis entirely. At least I don't see a reason, why it would have any particular impact. When using only the secondary axis as an input it would make sense to me to rotate first around what is selected as primary axis. Right now it seems a bit random to me, not sure of the logic behind it right now. e.g. this shouldn't result in any rotation imo ![image](/attachments/a8d55d6e-aaff-42bd-8857-e8314efa8fe1)

image.png

28 KiB

With the rotation socket in 4.0, we have another opportunity to add this node. But it needs to be updated for that.

 @ -9901,0 +9922,4 @@
   RNA_def_property_ui_text(
       prop,
       "Secondary Axis",
       "Axis that is aligned as good as possible given the alignment of the primary axis");

 @ -0,0 +38,4 @@
   uiItemR(layout, ptr, "secondary_axis", UI_ITEM_R_EXPAND, nullptr, ICON_NONE);
   if (storage.primary_axis == storage.secondary_axis) {
     uiItemL(layout, N_("Must not be equal"), ICON_ERROR);

 @ -0,0 +70,4 @@
     /* Through cancellation this will set the last axis to be the one that's neither the primary
      * nor secondary axis. */
     tertiary_axis_ = (0 + 1 + 2) - primary_axis - secondary_axis;

 @ -0,0 +94,4 @@
     const float tertiary_factor = invert_tertiary ? -1.0f : 1.0f;
     for (const int64_t i : mask) {
       float3 primary = math::normalize(primaries[i]);

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Geometry Nodes: new Axis to Euler node #104416

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