PLYLoader: BufferGeometry and Blender style

[Mugen87]

I've used this version of PLYLoader in my last project. Features:

• It creates an indexed BufferGeometry instead of Geometry
• It can import geometries with vertices, vertex normals, vertex uvs, vertex colors and faces. The expected file format conforms to the Blender PLY implementation. So a simple plane geometry looks like this:

ply
format ascii 1.0
comment Created by Blender 2.74 (sub 0) - www.blender.org, source file: 'threejs_PLY_test.blend'
element vertex 4
property float x
property float y
property float z
property float nx
property float ny
property float nz
property float s
property float t
property uchar red
property uchar green
property uchar blue
element face 1
property list uchar uint vertex_indices
end_header
-4.281084 -4.281084 0.000000 0.000000 0.000000 1.000000 0.000000 0.000000 90 70 255
4.281084 -4.281084 0.000000 0.000000 0.000000 1.000000 1.000000 0.000000 90 70 255
4.281084 4.281084 0.000000 0.000000 0.000000 1.000000 1.000000 1.000000 90 70 255
-4.281084 4.281084 0.000000 0.000000 0.000000 1.000000 0.000000 1.000000 90 70 255
4 0 1 2 3

• I've tested the implementation with the existing dolphins example and some other files.
• The drawback of this approach is that it reverts support texture coordinates in ply parser #9121. It's very tricky to convert a geometry with face UVs in an indexed geometry object. Because there is no formal specification for PLY geometry with UVs, i recommend to adapt the Blender approach which maps very nicely to our BufferGeometry.
• Finally, this PR solves PLYLoader fails if the file has "vertex_index" instead of "vertex_indices" #9338

[mrdoob]

Sweeeet! 😀

[mrdoob]

Thanks!

[makc]

It's very tricky to convert a geometry with face UVs in an indexed geometry object.

wait, what?

[mrdoob]

It's very tricky to convert a geometry with face UVs in an indexed geometry object.

How about we produce non-indexed geometry instead?

[Mugen87]

Because BufferGeometry.computeVertexNormals() provides better results with an indexed geometry, I always try to create this type of geometry if possible.

Many PLY files just contain vertices and faces. Users will benefit from better normal data via computeVertexNormals if PLYLoader produces an indexed geometry.

[makc]

ok, I did not check r80+ but r79 has classic Geometry that can be converted to BufferGeometry, and classic Geometry is indexed and has UVs. where did the code go that does this black magic? removed from 3js entirely?

[mrdoob]

@makc we're trying to move everything to BufferGeometry so stuff loads faster and uses less memory. Unfortunately we have to lose some things while we transition.