Immediate Geometry Texturing

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:bust_in_silhouette: Asked By NewDevTrying

Hello All,

I am currently experimenting with using intimidate geometry in one of my projects. I have used this as I have some dynamic models that vary frame on frame.

Although at my current point I am struggling to get a texture applied to the mesh I am creating. I was wondering if any of you had some pointers of how to get this done or an example that I could work backwards so I can learn?

My main goal would be to get a texture applied to the whole model, the nice to have down the line will be to apply sharers ect to make it nicer but for now just a simple static texture applied to the model will be nice.

If it is not possible to apply a texture then i would appropriate some guidance of how to properly color the model.

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:bust_in_silhouette: Reply From: Zylann

Textures need texture coordinates, a.k.a UVs. These are regular Vector2 attributes you can add when building your geometry, for each vertex.
For example, a quad made of 4 vertices might have the following UVs: (0,0), (1, 0), (1, 1), (0, 1).
More complex models require to think about “unwrapping”, like a paper origami, to properly layout the UVs. It can be based on typical primitives like cylinders, quads or spheres, which have several known working UV layouts.

A quick alternative for really complex models is to use triplanar mapping. This technique generates UVs based on vertex coordinates, at the cost of a few more computations in the shader, so that your mesh doesn’t need to have UVs. You can toggle this option in SpatialMaterial.

Note: the same applies to colors. You can color a model by changing albedo in the material, but you can also specify colors per vertex (if the material has use_vertex_color_as_albedo checked).

So at what point do I create this UV, will I have to dynamically create it each frame after I have used my calls to create the immediate geometry?

Also how is it possible to unwrap intimidate geometry as its mesh is not known at build time?

NewDevTrying | 2019-07-17 19:02

You have to do it for every vertex that you add to ImmediateGeometry. This is per vertex, so that the renderer knows which coordinate of the texture to use on every specific point of the mesh:

immediate_geometry.set_uv(uv1) # Used for the next vertex
immediate_geometry.add_vertex(position1)

immediate_geometry.set_uv(uv2) # Used for the next vertex
immediate_geometry.add_vertex(position2)

immediate_geometry.set_uv(uv3) # Used for the next vertex
immediate_geometry.add_vertex(position3)

# etc

You might not know the mesh beforehands, but maybe you know at least what kind of mesh it is. Is it a ribbon? A tube? A heightmap? A completely arbitrary shape? If it’s the latter, triplanar shading might be easier.

Zylann | 2019-07-17 19:44

Ok, so I guess if you use set_uv, add_vertex pairs Then after I just apply a texture as normal once to the overall mesh?

NewDevTrying | 2019-07-17 19:49

Yes once you have UVs you can apply textures from a SpatialMaterial.

Zylann | 2019-07-17 19:50

thanks very much

NewDevTrying | 2019-07-17 20:43

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How would i set the color of a Vertex in an Immediate Mesh?