"gltfviewer -s" results in no lighting

[JackKaiXing]

Describe the bug
in windows, command "gltf_viewer my.gltf", that point lighting effect is visible; however, command "gltf_viewer -s my.gltf",that point lighting effect is gone. However, we do not want to scale the scene.

Expected behavior
how could be modify the code to control this?

[JackKaiXing]

thanks in advance

[romainguy]

There’s a directional light by default, no point lights. Could you provide screenshots please? Directional lighting works with or without -s in all my tests.

[JackKaiXing]

without -s

with -s

and here is my gltf string, as listed below:
{
"asset": {
"version": "2.0",
},
"extensionsUsed": [
"KHR_lights_punctual",
"KHR_draco_mesh_compression"
],
"scene": 0,
"scenes": [
{
"nodes": [
0,
1,
2
]
}
],
"nodes": [
{
"mesh": 0,
"translation": [
-0.5439453,
0,
8.354431
],
"name": "Box001",
"rotation": [
0,
0,
0,
1
],
"scale": [
1,
1,
1
]
},
{
"translation": [
8.409393,
24.04018,
11.8579865
],
"rotation": [
-0.707106769,
0,
0,
0.707106769
],
"name": "PhotometricLight001",
"extensions": {
"KHR_lights_punctual": {
"light": 0
}
},
"scale": [
1,
1,
1
]
},
{
"translation": [
4.13425446,
-16.18853,
12.9804688
],
"rotation": [
-0.707106769,
0,
0,
0.707106769
],
"name": "PhotometricLight002",
"extensions": {
"KHR_lights_punctual": {
"light": 1
}
},
"scale": [
1,
1,
1
]
}
],
"meshes": [
{
"primitives": [
{
"attributes": {
"POSITION": 1,
"TANGENT": 2,
"NORMAL": 3,
"TEXCOORD_0": 4
},
"indices": 0,
"material": 0,
"mode": 4,
"extensions": {
"KHR_draco_mesh_compression": {
"bufferView": 0,
"attributes": {
"POSITION": 0,
"TANGENT": 1,
"NORMAL": 2,
"TEXCOORD_0": 3
}
}
}
}
],
"name": "Box001"
}
],
"accessors": [
{
"componentType": 5123,
"count": 36,
"type": "SCALAR",
"name": "accessorIndices"
},
{
"componentType": 5126,
"count": 24,
"max": [
58.259484098680986,
11.356984611626771,
62.89313910600879
],
"min": [
-58.2570391060088,
-0.061389106008793354,
-62.893139106008796
],
"type": "VEC3",
"name": "accessorPositions"
},
{
"componentType": 5126,
"count": 24,
"type": "VEC4",
"name": "accessorTangents"
},
{
"componentType": 5126,
"count": 24,
"type": "VEC3",
"name": "accessorNormals"
},
{
"componentType": 5126,
"count": 24,
"type": "VEC2",
"name": "accessorUVs"
}
],
"bufferViews": [
{
"buffer": 0,
"byteOffset": 0,
"byteLength": 573
}
],
"buffers": [
{
"name": "test",
"byteLength": 576,
"uri": "test.bin"
}
],
"materials": [
{
"pbrMetallicRoughness": {
"baseColorFactor": [
0.1764706,
0.388235331,
0.24313727,
1
],
"metallicFactor": 0,
"roughnessFactor": 1
},
"name": "01 - Default",
"emissiveFactor": [
0,
0,
0
],
"alphaMode": "OPAQUE",
"doubleSided": false
}
],
"extensions": {
"KHR_lights_punctual": {
"lights": [
{
"color": [
2.78720665,
0.5679655,
0.000001
],
"intensity": 10000,
"type": "point"
},
{
"color": [
0.904883146,
1.0083766,
1.19620013
],
"intensity": 10000,
"type": "point"
}
]
}
},
"extensionsRequired": [
"KHR_draco_mesh_compression"
]
}

[JackKaiXing]

In my gltf, there are two point light. we checked the code, without -s, gltf_viewer would execute function "fitIntoUnitCube", why is that?

[romainguy]

It does this so the loaded glTF can be visible from the default camera position and entirely visible on screen. This is a pretty common thing to do in 3D viewers.

[romainguy]

Can you please share the entire glTF file with us?

@prideout @bejado Any idea why scale would impact lights? I imagine we don't rescale their falloff which would explain why it's more visible without -s.

[bejado]

If the glTF file doesn't have a range set for punctual lights, we give it an arbitrary one (10.0 units I believe). When using -s, the light and geometry probably fall outside this arbitrary range. Perhaps we should be scaling this falloff, or at least using the surrounding AABB to dictate the falloff value.

[JackKaiXing]

The entire glTF file.

https://github.com/JackKaiXing/glTF/tree/master/glTF

[romainguy]

@bejado That must be it then, I don't see a range in the glTF file.

[JackKaiXing]

Based on the above discussion, we added "range":4000 for light property. with -s, lighting is still invisible.

[romainguy]

I can't open the glTF file in Blender because of the Draco mesh compression extension.

@JackKaiXing Sorry to bother you, do you have a version of the asset that doesn't use Draco? I'd like to check where the lights are.

[JackKaiXing]

@romainguy .

gltf with no draco compression: https://github.com/JackKaiXing/glTF/tree/master/glTF/gltf_WithoutDraco

[romainguy]

The positions are correct, so either there's a bug on our side or it's simply that the intensity of the lights isn't enough for the distances because of the falloff.

@JackKaiXing Could you try with brighter lights?