Draco Compression Issue with EXT_instance_features and EXT_mesh_gpu_instancing Extensions
lanvada opened this issue · comments
Hello,
I encountered an issue while using Draco's compression feature on a GLB file that utilizes the EXT_instance_features and EXT_mesh_gpu_instancing extensions. After compression, the resulting file appears to be corrupted.
It seems that the buffer view responsible for GPU instancing has been removed in the compressed file's JSON. This removal breaks the model's ability to load correctly and fails format validation checks.
Could you please look into this issue? Any help or guidance on how to address this problem would be greatly appreciated.
Thank you!
Below are the JSON sections of the GLB files before and after compression.
- JSON before compression:
{
"asset": { "generator": "Smhc.Graphics.Gltf@1.2.3.9", "version": "2.0" },
"scene": 0,
"scenes": [
{
"name": "root scene",
"nodes": [0],
"extras": {
"name": "rac_basic_sample_project",
"isBIMModel": "true",
"modelGuid": "f2415188-5743-41f7-9117-8b195905cb43"
}
}
],
"nodes": [
{ "name": "root", "children": [1] },
{ "name": "instanced", "children": [2, 3] },
{
"name": "705e25a1-127e-4d76-b5f5-4e766ef073a3-000f1bef",
"mesh": 0,
"extensions": {
"EXT_mesh_gpu_instancing": {
"attributes": {
"TRANSLATION": 6,
"ROTATION": 7,
"SCALE": 8,
"_FEATURE_ID_0": 9
}
},
"EXT_instance_features": {
"featureIds": [{ "featureCount": 4, "attribute": 0 }]
}
}
},
{
"name": "705e25a1-127e-4d76-b5f5-4e766ef073a3-000f1d9e",
"mesh": 1,
"extensions": {
"EXT_mesh_gpu_instancing": {
"attributes": {
"TRANSLATION": 10,
"ROTATION": 11,
"SCALE": 12,
"_FEATURE_ID_0": 13
}
},
"EXT_instance_features": {
"featureIds": [{ "featureCount": 4, "attribute": 0 }]
}
}
}
],
"meshes": [
{
"name": "SM_Dining Chair (3)",
"primitives": [
{
"attributes": { "POSITION": 0, "NORMAL": 1 },
"indices": 2,
"material": 0
}
]
},
{
"name": "SM_Dining Chair (3)",
"primitives": [
{
"attributes": { "POSITION": 3, "NORMAL": 4 },
"indices": 5,
"material": 0
}
]
}
],
"accessors": [
{
"bufferView": 0,
"byteOffset": 0,
"componentType": 5126,
"count": 4766,
"type": "VEC3",
"max": [0.4006734, 0.7755031, 0.4090699],
"min": [-0.006043643, -0.0006093467, -0.0308729019]
},
{
"bufferView": 1,
"byteOffset": 0,
"componentType": 5126,
"count": 4766,
"type": "VEC3",
"max": [1.0, 1.0, 0.9998036],
"min": [-1.0, -1.0, -0.9998036]
},
{
"bufferView": 2,
"byteOffset": 0,
"componentType": 5123,
"count": 23328,
"type": "SCALAR"
},
{
"bufferView": 3,
"byteOffset": 0,
"componentType": 5126,
"count": 4766,
"type": "VEC3",
"max": [0.4006734, 0.7755031, 0.4090699],
"min": [-0.006043643, -0.0006093467, -0.0308729019]
},
{
"bufferView": 4,
"byteOffset": 0,
"componentType": 5126,
"count": 4766,
"type": "VEC3",
"max": [1.0, 1.0, 0.9998036],
"min": [-1.0, -1.0, -0.9998036]
},
{
"bufferView": 5,
"byteOffset": 0,
"componentType": 5123,
"count": 23328,
"type": "SCALAR"
},
{
"bufferView": 6,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "VEC3"
},
{
"bufferView": 7,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "VEC4"
},
{
"bufferView": 8,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "VEC3"
},
{
"bufferView": 9,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "SCALAR"
},
{
"bufferView": 10,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "VEC3"
},
{
"bufferView": 11,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "VEC4"
},
{
"bufferView": 12,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "VEC3"
},
{
"bufferView": 13,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "SCALAR"
}
],
"bufferViews": [
{
"byteOffset": 0,
"buffer": 0,
"byteLength": 57192,
"byteStride": 12,
"target": 34962
},
{
"byteOffset": 57192,
"buffer": 0,
"byteLength": 57192,
"byteStride": 12,
"target": 34962
},
{ "byteOffset": 114384, "buffer": 0, "byteLength": 46656, "target": 34963 },
{
"byteOffset": 161040,
"buffer": 0,
"byteLength": 57192,
"byteStride": 12,
"target": 34962
},
{
"byteOffset": 218232,
"buffer": 0,
"byteLength": 57192,
"byteStride": 12,
"target": 34962
},
{ "byteOffset": 275424, "buffer": 0, "byteLength": 46656, "target": 34963 },
{ "byteOffset": 322080, "buffer": 0, "byteLength": 48, "byteStride": 12 },
{ "byteOffset": 322128, "buffer": 0, "byteLength": 64, "byteStride": 16 },
{ "byteOffset": 322192, "buffer": 0, "byteLength": 48, "byteStride": 12 },
{ "byteOffset": 322240, "buffer": 0, "byteLength": 16, "byteStride": 4 },
{ "byteOffset": 322256, "buffer": 0, "byteLength": 48, "byteStride": 12 },
{ "byteOffset": 322304, "buffer": 0, "byteLength": 64, "byteStride": 16 },
{ "byteOffset": 322368, "buffer": 0, "byteLength": 48, "byteStride": 12 },
{ "byteOffset": 322416, "buffer": 0, "byteLength": 16, "byteStride": 4 }
],
"materials": [
{
"name": "M_Phase - Exist",
"pbrMetallicRoughness": {
"baseColorFactor": [0.498039216, 0.498039216, 0.498039216, 1.0],
"metallicFactor": 0.0,
"roughnessFactor": 0.609375
},
"doubleSided": true
}
],
"buffers": [
{ "name": "53056330-2811-4816-84ba-b5022378e0d3", "byteLength": 322432 }
],
"extensionsUsed": ["EXT_mesh_gpu_instancing", "EXT_instance_features"],
"extensionsRequired": ["EXT_mesh_gpu_instancing"]
}
- JSON after compression:
{
"asset": { "generator": "Smhc.Graphics.Gltf@1.2.3.9", "version": "2.0" },
"scene": 0,
"scenes": [
{
"name": "root scene",
"nodes": [0],
"extras": {
"name": "rac_basic_sample_project",
"isBIMModel": "true",
"modelGuid": "f2415188-5743-41f7-9117-8b195905cb43"
}
}
],
"nodes": [
{ "name": "root", "children": [1] },
{ "name": "instanced", "children": [2, 3] },
{
"name": "705e25a1-127e-4d76-b5f5-4e766ef073a3-000f1bef",
"mesh": 0,
"extensions": {
"EXT_mesh_gpu_instancing": {
"attributes": {
"TRANSLATION": 6,
"ROTATION": 7,
"SCALE": 8,
"_FEATURE_ID_0": 9
}
},
"EXT_instance_features": {
"featureIds": [{ "featureCount": 4, "attribute": 0 }]
}
}
},
{
"name": "705e25a1-127e-4d76-b5f5-4e766ef073a3-000f1d9e",
"mesh": 1,
"extensions": {
"EXT_mesh_gpu_instancing": {
"attributes": {
"TRANSLATION": 10,
"ROTATION": 11,
"SCALE": 12,
"_FEATURE_ID_0": 13
}
},
"EXT_instance_features": {
"featureIds": [{ "featureCount": 4, "attribute": 0 }]
}
}
}
],
"meshes": [
{
"name": "SM_Dining Chair (3)",
"primitives": [
{
"attributes": { "POSITION": 3, "NORMAL": 4 },
"indices": 2,
"material": 0,
"mode": 4,
"extensions": {
"KHR_draco_mesh_compression": {
"bufferView": 2,
"attributes": { "POSITION": 0, "NORMAL": 1 }
}
}
}
]
},
{
"name": "SM_Dining Chair (3)",
"primitives": [
{
"attributes": { "POSITION": 6, "NORMAL": 7 },
"indices": 5,
"material": 0,
"mode": 4,
"extensions": {
"KHR_draco_mesh_compression": {
"bufferView": 3,
"attributes": { "POSITION": 0, "NORMAL": 1 }
}
}
}
]
}
],
"accessors": [
{
"bufferView": 0,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "VEC3"
},
{
"bufferView": 1,
"byteOffset": 0,
"componentType": 5126,
"count": 4,
"type": "SCALAR"
},
{ "componentType": 5123, "count": 23328, "type": "SCALAR" },
{
"componentType": 5126,
"count": 4766,
"type": "VEC3",
"max": [0.40068262341435573, 0.7755149427168185, 0.4090840279070497],
"min": [
-0.006055485716818494, -0.000621189416818494, -0.030884744616818494
]
},
{
"componentType": 5126,
"count": 4766,
"type": "VEC3",
"max": [1.007843137254902, 1.007843137254902, 1.008039537254902],
"min": [-1.007843137254902, -1.007843137254902, -1.007646737254902]
},
{ "componentType": 5123, "count": 23328, "type": "SCALAR" },
{
"componentType": 5126,
"count": 4766,
"type": "VEC3",
"max": [0.40068262341435573, 0.7755149427168185, 0.4090840279070497],
"min": [
-0.006055485716818494, -0.000621189416818494, -0.030884744616818494
]
},
{
"componentType": 5126,
"count": 4766,
"type": "VEC3",
"max": [1.007843137254902, 1.007843137254902, 1.008039537254902],
"min": [-1.007843137254902, -1.007843137254902, -1.007646737254902]
}
],
"bufferViews": [
{ "byteOffset": 0, "buffer": 0, "byteLength": 48, "byteStride": 12 },
{ "byteOffset": 48, "buffer": 0, "byteLength": 16, "byteStride": 4 },
{ "buffer": 0, "byteOffset": 64, "byteLength": 77274 },
{ "buffer": 0, "byteOffset": 77344, "byteLength": 77274 }
],
"materials": [
{
"name": "M_Phase - Exist",
"pbrMetallicRoughness": {
"baseColorFactor": [0.498039216, 0.498039216, 0.498039216, 1],
"metallicFactor": 0,
"roughnessFactor": 0.609375
},
"doubleSided": true,
"emissiveFactor": [0, 0, 0],
"alphaMode": "OPAQUE"
}
],
"buffers": [
{ "name": "rac_basic_sample_project_test_draco", "byteLength": 154624 }
],
"extensionsUsed": [
"EXT_mesh_gpu_instancing",
"EXT_instance_features",
"KHR_draco_mesh_compression"
],
"extensionsRequired": [
"EXT_mesh_gpu_instancing",
"KHR_draco_mesh_compression"
]
}
glb model:
rac_basic_sample_project_test.zip
I have fixed this issue myself.