例如：
[ // vertex buffer
0,0,0,
0,1,0,
1,0,0,
1,1,0,
]
并绘制简单的
LINES：[ // index buffer
0,2,
2,4,
4,0,
0,1,
1,4,
]
我想知道如何创建包含这些缓冲区的glTF文件吗？
我想避免使用COLLADA和COLLADA2GLTF，因为这只会增加一个额外的步骤，并且可能只会膨胀生成的glTF文件。
#1 楼
在为教程创建一组glTF模型时，我还打算创建最小的glTF文件。更新：以下内容指的是glTF 1.0 / 1.1。请参见下面的示例，将其更新为glTF 2.0。
正如5chdn在答复中已经提到的，可能是一个问题。根据规范的附录A：默认材质，不包含材质的资产应使用默认材质渲染，该材质仅以均匀的50％灰色显示对象。
有些观众可能不支持这一点，即使他们支持，在规范方面也有一些细微之处：在glTF 1.0中，仍然有必要定义“空”材料，因为
mesh.primitive.material属性尚未可选。但这应该在glTF 1.1中修复。 因此，以下内容实际上应该是最小的glTF资产（1.1版）：
{
"scenes" : {
"scene0" : {
"nodes" : [ "node0" ]
}
},
"nodes" : {
"node0" : {
"meshes" : [ "mesh0" ]
}
},
"meshes" : {
"mesh0" : {
"primitives" : [ {
"attributes" : {
"POSITION" : "positionsAccessor"
}
} ]
}
},
"buffers" : {
"buffer0" : {
"uri" : "data:application/octet-stream;base64,AAAAAAAAAAAAAAAAAACAPwAAAAAAAAAAAAAAAAAAgD8AAAAA",
"byteLength" : 36
}
},
"bufferViews" : {
"positionsBufferView" : {
"buffer" : "buffer0",
"byteOffset" : 0,
"byteLength" : 36,
"target" : 34962
}
},
"accessors" : {
"positionsAccessor" : {
"bufferView" : "positionsBufferView",
"byteOffset" : 0,
"componentType" : 5126,
"count" : 3,
"type" : "VEC3",
"max" : [ 1.0, 1.0, 0.0 ],
"min" : [ 0.0, 0.0, 0.0 ]
}
},
"asset" : {
"version" : "1.1"
}
}
它还显示了一个三角形：
没有嵌入式缓冲区的版本可以在https://github.com/javagl/gltfTutorialModels上找到，以及带有索引的三角形可以在https：// github上找到。 com / javagl / gltfTutorialModels / tree / master / Triangle
glTF 2.0的更新：
glTF 2.0的概念和顶级元素与glTF 1.0基本相同。但是格式仍然有所变化。最重要的是（对于这个小例子），顶级字典现在是数组。以下是与上述相同的“三角”模型，并进行了相应的更新：
{
"scenes":[
{
"nodes":[ 0 ]
}
],
"nodes":[
{
"mesh":0
}
],
"meshes":[
{
"primitives":[
{
"attributes":{
"POSITION":1
},
"indices":0
}
]
}
],
"buffers":[
{
"uri":"data:application/octet-stream;base64,AAABAAIAAAAAAAAAAAAAAAAAAAAAAIA/AAAAAAAAAAAAAAAAAACAPwAAAAA=",
"byteLength":44
}
],
"bufferViews":[
{
"buffer":0,
"byteOffset":0,
"byteLength":6,
"target":34963
},
{
"buffer":0,
"byteOffset":8,
"byteLength":36,
"target":34962
}
],
"accessors":[
{
"bufferView":0,
"byteOffset":0,
"componentType":5123,
"count":3,
"type":"SCALAR",
"max":[
2
],
"min":[
0
]
},
{
"bufferView":1,
"byteOffset":0,
"componentType":5126,
"count":3,
"type":"VEC3",
"max":[
1.0,
1.0,
0.0
],
"min":[
0.0,
0.0,
0.0
]
}
],
"asset":{
"version":"2.0"
}
}
可以在glTF示例模型存储库中找到此glTF示例模型。
#2 楼
您可以将数据放入数据uri中以base64格式内联存储数据。"buffers": {
"a-buffer-id": {
"byteLength": 1024,
"type": "arraybuffer",
"uri"="data:application/octet-stream;base64,..."
}
},
与将数据存储在二进制文件中相比，它仍然有点肿。
#3 楼
在花了一些时间了解gltf文件中二进制缓冲区的工作方式之后，我终于设法生成了一个真正最小的gltf文件。这是一个黄色三角形（演示）。
我试图从gltf中删除不需要的所有内容。这似乎是必需的（github）：
{
"accessors": {
"accessor0": {
"bufferView": "bufferView0",
"byteOffset": 0,
"componentType": 5123,
"count": 3,
"type": "SCALAR"
},
"accessor1": {
"bufferView": "bufferView1",
"byteOffset": 0,
"byteStride": 12,
"componentType": 5126,
"count": 3,
"max": [
0.5,
0.5,
0.5
],
"min": [
0.0,
0.0,
0.0
],
"type": "VEC3"
}
},
"asset": {
"generator": "5chdn",
"profile": {
"api": "WebGL",
"version": "1.0.3"
},
"version": "1.0",
"extras": {
"description": "minimal gltf, single triangle",
"base64encoder": "https://jsfiddle.net/opkxy0xb/",
"stackexchange": "https://computergraphics.stackexchange.com/q/1934/361"
}
},
"bufferViews": {
"bufferView0": {
"buffer": "Min",
"byteLength": 6,
"byteOffset": 0,
"target": 34963
},
"bufferView1": {
"buffer": "Min",
"byteLength": 36,
"byteOffset": 6,
"target": 34962
}
},
"buffers": {
"Min": {
"bytelength": 42,
"type": "arraybuffer",
"uri": "data:application/octet-stream;base64,AAABAAIArK34PnZxmz29UhY9T6+UPXuD7z64QAI9UWuaPW/wBT3ysPA+"
}
},
"materials": {
"effect0": {
"values": {
"emission": [
0.8,
0.8,
0.0,
1.0
]
},
"technique": "technique0"
}
},
"meshes": {
"mesh0": {
"name": "Triangle",
"primitives": [
{
"attributes": {
"POSITION": "accessor1"
},
"indices": "accessor0",
"material": "effect0",
"mode": 4
}
]
}
},
"nodes": {
"node0": {
"matrix": [
1,
0,
0,
0,
0,
1,
0,
0,
0,
0,
1,
0,
0,
0,
0,
1
],
"meshes": [
"mesh0"
],
"name": "TriangleMesh"
}
},
"programs": {
"program0": {
"attributes": [
"a_position"
],
"fragmentShader": "fragmentShader0",
"vertexShader": "vertexShader0"
}
},
"scenes": {
"scene0": {
"nodes": [
"node0"
]
}
},
"shaders": {
"vertexShader0": {
"type": 35633,
"uri": "data:text/plain;base64,cHJlY2lzaW9uIGhpZ2hwIGZsb2F0Ow0KdW5pZm9ybSBtYXQ0IHVfbW9kZWxWaWV3TWF0cml4Ow0KdW5pZm9ybSBtYXQ0IHVfcHJvamVjdGlvbk1hdHJpeDsNCmF0dHJpYnV0ZSB2ZWMzIGFfcG9zaXRpb247DQp2b2lkIG1haW4odm9pZCkNCnsNCmdsX1Bvc2l0aW9uID0gdV9wcm9qZWN0aW9uTWF0cml4ICogdV9tb2RlbFZpZXdNYXRyaXggKiB2ZWM0KGFfcG9zaXRpb24sMS4wKTsNCn0="
},
"fragmentShader0": {
"type": 35632,
"uri": "data:text/plain;base64,cHJlY2lzaW9uIGhpZ2hwIGZsb2F0Ow0KdW5pZm9ybSB2ZWM0IHVfZW1pc3Npb247DQp2b2lkIG1haW4odm9pZCkNCnsNCmdsX0ZyYWdDb2xvciA9IHVfZW1pc3Npb247DQp9"
}
},
"techniques": {
"technique0": {
"attributes": {
"a_position": "position"
},
"parameters": {
"modelViewMatrix": {
"semantic": "MODELVIEW",
"type": 35676
},
"projectionMatrix": {
"semantic": "PROJECTION",
"type": 35676
},
"emission": {
"type": 35666
},
"position": {
"semantic": "POSITION",
"type": 35665
}
},
"program": "program0",
"states": {
"enable": [
2884,
2929
]
},
"uniforms": {
"u_modelViewMatrix": "modelViewMatrix",
"u_projectionMatrix": "projectionMatrix",
"u_emission": "emission"
}
}
}
}
一个好的起点是gltf规范的附录A，它定义了默认的材质和着色器。我要做的就是添加场景描述和缓冲区。