Why AxesViewer need to be scaled to match base unit?

ylacaute · February 18, 2024, 9:20am

Hi !

This playground shows that we have to scale AxesViewer at 0.74 to match a babylon unit, is that the expected behavior ? Why AxesViewer is not 1 by default ?

Thanks

Cedric · February 19, 2024, 8:19am

It looks like it’s on purpose

github.com

BabylonJS/Babylon.js/blob/aeec5b9613b6d15942860ae6aba11b6792900b97/packages/dev/core/src/Gizmos/axisDragGizmo.ts#L106


      
                  height: 0.075,

                  diameterBottom: 0.0375 * (1 + (thickness - 1) / 4),

                  tessellation: 96,

              },

              scene

          );

          const line = CreateCylinder(

              "cylinder",

              {

                  diameterTop: 0.005 * thickness,

                  height: 0.275,

                  diameterBottom: 0.005 * thickness,

                  tessellation: 96,

              },

              scene

          );

          

          // Position arrow pointing in its drag axis

          cylinder.parent = arrow;

          cylinder.material = material;

          cylinder.rotation.x = Math.PI / 2;

I guess for legacy reason. the use of axisViewer is to display axis, not to mesure the world unit.
I agree it’s a bit weird.

Did you see that before @Philippe ?

Philippe · March 1, 2024, 9:58am

Unfortunately, I don’t know more. My changes did only format this part.

From what I can see from the git history the value 0.275 seems to be introduced in use cylinders instead of lines · BabylonJS/Babylon.js@d3d8de8 · GitHub by @TrevorDev maybe he has some insights ?

Cedric · March 1, 2024, 10:38am

Looks like it’s for no special meaning. if you want to update the scale for a unit instead, feel free to open a PR

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Why AxesViewer need to be scaled to match base unit?

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