vbo_rendering(3)

✨ NAME ✨

vbo_rendering — vertex array and VBO rendering in Coin 💅

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okay bestie, sit down, because this one is genuinely iconic. Coin 2.5 rolled up with way better support for OpenGL vertex array and VBO rendering, and the glow-up is real — this can mean major rendering performance improvements compared to the old rendering code. no cap. 🔥

The new rendering code got added for these nodes:

• SoIndexedFaceSet
• SoVRMLIndexedFaceSet
• SoIndexedLineSet
• SoVRMLIndexedLineSet
• SoPointSet
• SoVRMLPointSet

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🦋 how to actually get the speed ✨

so to take advantage of the improved performance that vertex array and VBO rendering yields, you gotta organize your vertex data in a way that makes it possible to render it with OpenGL vertex arrays. and here's the catch, bestie: OpenGL vertex array rendering does not support multiple index arrays. so literally all your vertex data — coordinates, normals, colors and texture coordinates — must use the same index array; or use OVERALL binding. 🎀

For the indexed nodes, that means PER_VERTEX_INDEXED and OVERALL are the only supported bindings for materials, normals and texture coordinates. And when PER_VERTEX_INDEXED binding is used, the corresponding index field should by empty. that's the signal to the shape to use the coordIndex field for indices. it's giving "just trust me, leave it blank." 🙈

Below is an example scene graph that will be rendered using vertex arrays:

NormalBinding { value PER_VERTEX_INDEXED }
Coordinate3 {
  point [
    0 0 0, # 0
    1 0 0, # 1
    2 0 0, # 2
    0 1 0, # 3
    1 1 0, # 4
    2 1 0, # 5
    0 2 0, # 6
    1 2 0, # 7
    2 2 0, # 8

    2 0  0, # 9
    2 0 -1, # 10
    2 1  0, # 11
    2 1 -1, # 12
    2 2  0, # 13
    2 2 -1  # 14
  ]
}
Normal {
  vector [
    0 0 1, # 0
    0 0 1, # 1
    0 0 1, # 2
    0 0 1, # 3
    0 0 1, # 4
    0 0 1, # 5
    0 0 1, # 6
    0 0 1, # 7
    0 0 1, # 8

    1 0 0,  # 9
    1 0 0,  # 10
    1 0 0,  # 11
    1 0 0,  # 12
    1 0 0,  # 13
    1 0 0   # 14
  ]
}

IndexedFaceSet {
  coordIndex [
    0, 1, 4, 3, -1,
    1, 2, 5, 4, -1,
    3, 4, 7, 6, -1,
    4, 5, 8, 7, -1,

    9, 10, 12, 11, -1,
    11, 12, 14, 13, -1
  ]
  normalIndex [ ] # = use coordIndex
}

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⚠️ please note that since only one index array can be used, it might be necessary to supply duplicate normals and coordinates to meet this requirement. yes, duplicates. it's a whole thing. 😭

also, if normals are needed, you have to supply them. a shape with autogenerated normals can't be rendered using vertex arrays (since a single coordinate might get multiple normals). so no lazy-mode normals, sorry. 💀

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🌸 the PointSet exception, because of course there's one 🫶

The PointSet nodes can always be rendered using vertex arrays, since these nodes haven't got index arrays — and the only bindings supported are PER_VERTEX and OVERALL. easy. no drama. ✨

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💜 and if you don't wanna do all that

If it's inconvenient to create vertex array ready scene graphs directly from your application, it's also possible to use SoReorganizeAction to reorganize the geometry before rendering. let the action do the heavy lifting, bestie. that's what it's there for. 👑

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that's the whole vibe. this page is from Coin, Version 2.5.0 — vbo_rendering(3), Library Functions Manual. go forth and render iconically. 🎀💖⭐