How to understanding of the vertex data obtained from StaticMesh

Development Programming & Scripting
,
1

Hello

I obtain the vertex data of the static mesh using the blueprint, as shown in the following figure.

BP
BP892×361 66.1 KB

Box center
Box center511×425 207 KB

The obtained vertex data is as follows

LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=-50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=-50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=50.000 Z=0.000

LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=50.000 Z=100.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=50.000 Z=100.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=-50.000 Z=100.000
LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=-50.000 Z=100.000

LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=50.000 Z=100.000
LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=50.000 Z=100.000

LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=-50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=-50.000 Z=100.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=50.000 Z=100.000

LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=-50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=-50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=-50.000 Z=100.000
LogBlueprintUserMessages: [NewMap_C_4] X=50.000 Y=-50.000 Z=100.000

LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=-50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=50.000 Z=0.000
LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=50.000 Z=100.000
LogBlueprintUserMessages: [NewMap_C_4] X=-50.000 Y=-50.000 Z=100.000

I understand that the following data represents the coordinates from the bottom origin to the four bottom vertices of the rectangular geometric shape. But why do vertex data like X=-50.000, Y=50.000, Z=0.000 appear repeatedly? How can I understand this? If there are repeated vertices, can it be interpreted as that other faces only have some of their vertices located at the overlapping positions?

X=-50.000 Y=50.000 Z=0.000
X=-50.000 Y=-50.000 Z=0.000
X=50.000 Y=-50.000 Z=0.000
X=50.000 Y=50.000 Z=0.000

2

Those repeats are normal. You are not getting the 8 unique corner positions. You are getting the render mesh vertices (wedges).

Your reading of the positions is right. A default engine cube is 100x100x100 with the pivot on the bottom face, so the corners sit at X/Y = +/-50 and Z = 0 or 100. A cube only has 8 unique positions, but the GPU mesh splits a corner wherever the normal or the UV changes. Each of the 6 faces keeps its own 4 corners so the faces can have hard edges and their own UVs. 6 x 4 = 24 vertices, which is the list you printed. X=-50 Y=50 Z=0 shows up once for the bottom face and again for each side face that shares that corner, because those copies have different normals. They are not extra geometry stacked in the same place. They are the same location stored once per face.

If you only need the 8 corners, unique the positions yourself: keep a list and skip a point when one within a small tolerance is already stored. If you need a watertight indexed mesh, weld by position and rebuild the index buffer. The Blueprint section / vertex nodes return the un-welded render data on purpose, so the repeats are the hard-edge splits, not a bug in the node.