Decode meshopt in buffer structure

specs/base/binary/BinaryBufferDataResolverSpec.ts

@@ -0,0 +1,143 @@
+import fs from "fs";
+import path from "path";
+
+import { BinaryBufferDataResolver } from "../../../src/base";
+import { ResourceResolvers } from "../../../src/base";
+
+import { SpecHelpers } from "../../SpecHelpers";
+
+const SPECS_DATA_BASE_DIRECTORY = SpecHelpers.getSpecsDataBaseDirectory();
+
+describe("BinaryBufferDataResolver", function () {
+  it("resolves the data from the buffer structure of a glTF", async function () {
+    const p = SPECS_DATA_BASE_DIRECTORY + "/Triangle/Triangle.gltf";
+    const directory = path.dirname(p);
+    const resourceResolver =
+      ResourceResolvers.createFileResourceResolver(directory);
+
+    const gltfBuffer = fs.readFileSync(p);
+    const gltf = JSON.parse(gltfBuffer.toString());
+    const binaryBufferData = await BinaryBufferDataResolver.resolve(
+      gltf,
+      undefined,
+      resourceResolver
+    );
+
+    // The indices are unsigned short (16 bit) integer values
+    const indicesBufferView = binaryBufferData.bufferViewsData[0];
+    const indicesArray = new Uint16Array(
+      indicesBufferView.buffer,
+      indicesBufferView.byteOffset,
+      indicesBufferView.byteLength / Uint16Array.BYTES_PER_ELEMENT
+    );
+    const actualIndices = [...indicesArray];
+    const expectedIndices = [0, 1, 2];
+
+    // The positions are float values
+    const positionsBufferView = binaryBufferData.bufferViewsData[1];
+    const positionsArray = new Float32Array(
+      positionsBufferView.buffer,
+      positionsBufferView.byteOffset,
+      positionsBufferView.byteLength / Float32Array.BYTES_PER_ELEMENT
+    );
+    const actualPositions = [...positionsArray];
+    // prettier-ignore
+    const expectedPositions = [
+      0.0, 0.0, 0.0, 
+      1.0, 0.0, 0.0, 
+      0.0, 1.0, 0.0
+    ];
+
+    expect(actualIndices).toEqual(expectedIndices);
+    expect(actualPositions).toEqual(expectedPositions);
+  });
+
+  it("resolves the data from the buffer structure of a glTF with meshopt compression", async function () {
+    const p = SPECS_DATA_BASE_DIRECTORY + "/Triangle/TriangleMeshopt.gltf";
+    const directory = path.dirname(p);
+    const resourceResolver =
+      ResourceResolvers.createFileResourceResolver(directory);
+
+    const gltfBuffer = fs.readFileSync(p);
+    const gltf = JSON.parse(gltfBuffer.toString());
+    const binaryBufferData = await BinaryBufferDataResolver.resolve(
+      gltf,
+      undefined,
+      resourceResolver
+    );
+
+    // The indices are unsigned short (16 bit) integer values
+    const indicesBufferView = binaryBufferData.bufferViewsData[0];
+    const indicesArray = new Uint16Array(
+      indicesBufferView.buffer,
+      indicesBufferView.byteOffset,
+      indicesBufferView.byteLength / Uint16Array.BYTES_PER_ELEMENT
+    );
+    const actualIndices = [...indicesArray];
+    const expectedIndices = [0, 1, 2];
+
+    // The positions are ALSO unsigned 16-bit integer values (normalized)
+    const positionsBufferView = binaryBufferData.bufferViewsData[1];
+    const positionsArray = new Uint16Array(
+      positionsBufferView.buffer,
+      positionsBufferView.byteOffset,
+      positionsBufferView.byteLength / Uint16Array.BYTES_PER_ELEMENT
+    );
+    const actualPositions = [...positionsArray];
+    // prettier-ignore
+    const expectedPositions = [
+      32769, 32769,     0,
+          0, 32767, 32769,
+          0,     0, 32769,
+      32767,     0,     0
+    ]
+
+    expect(actualIndices).toEqual(expectedIndices);
+    expect(actualPositions).toEqual(expectedPositions);
+  });
+
+  it("resolves the data from the buffer structure of a glTF without default byte offsets with meshopt compression", async function () {
+    const p =
+      SPECS_DATA_BASE_DIRECTORY + "/Triangle/TriangleMeshoptNoByteOffset.gltf";
+    const directory = path.dirname(p);
+    const resourceResolver =
+      ResourceResolvers.createFileResourceResolver(directory);
+
+    const gltfBuffer = fs.readFileSync(p);
+    const gltf = JSON.parse(gltfBuffer.toString());
+    const binaryBufferData = await BinaryBufferDataResolver.resolve(
+      gltf,
+      undefined,
+      resourceResolver
+    );
+
+    // The indices are unsigned short (16 bit) integer values
+    const indicesBufferView = binaryBufferData.bufferViewsData[0];
+    const indicesArray = new Uint16Array(
+      indicesBufferView.buffer,
+      indicesBufferView.byteOffset,
+      indicesBufferView.byteLength / Uint16Array.BYTES_PER_ELEMENT
+    );
+    const actualIndices = [...indicesArray];
+    const expectedIndices = [0, 1, 2];
+
+    // The positions are ALSO unsigned 16-bit integer values (normalized)
+    const positionsBufferView = binaryBufferData.bufferViewsData[1];
+    const positionsArray = new Uint16Array(
+      positionsBufferView.buffer,
+      positionsBufferView.byteOffset,
+      positionsBufferView.byteLength / Uint16Array.BYTES_PER_ELEMENT
+    );
+    const actualPositions = [...positionsArray];
+    // prettier-ignore
+    const expectedPositions = [
+      32769, 32769,     0,
+          0, 32767, 32769,
+          0,     0, 32769,
+      32767,     0,     0
+    ]
+
+    expect(actualIndices).toEqual(expectedIndices);
+    expect(actualPositions).toEqual(expectedPositions);
+  });
+});

specs/data/Triangle/TriangleMeshopt.gltf

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+{
+  "asset": {
+    "generator": "glTF-Transform v3.10.1",
+    "version": "2.0"
+  },
+  "accessors": [
+    {
+      "type": "SCALAR",
+      "componentType": 5123,
+      "count": 3,
+      "normalized": false,
+      "byteOffset": 0,
+      "bufferView": 0
+    },
+    {
+      "type": "VEC3",
+      "componentType": 5122,
+      "count": 3,
+      "max": [
+        32767,
+        32767,
+        0
+      ],
+      "min": [
+        -32767,
+        -32767,
+        0
+      ],
+      "normalized": true,
+      "byteOffset": 0,
+      "bufferView": 1
+    }
+  ],
+  "bufferViews": [
+    {
+      "buffer": 1,
+      "byteOffset": 0,
+      "byteLength": 6,
+      "target": 34963,
+      "extensions": {
+        "EXT_meshopt_compression": {
+          "buffer": 0,
+          "byteOffset": 0,
+          "byteLength": 18,
+          "mode": "TRIANGLES",
+          "byteStride": 2,
+          "count": 3
+        }
+      }
+    },
+    {
+      "buffer": 1,
+      "byteOffset": 8,
+      "byteLength": 24,
+      "target": 34962,
+      "byteStride": 8,
+      "extensions": {
+        "EXT_meshopt_compression": {
+          "buffer": 0,
+          "byteOffset": 20,
+          "byteLength": 60,
+          "mode": "ATTRIBUTES",
+          "byteStride": 8,
+          "count": 3
+        }
+      }
+    }
+  ],
+  "buffers": [
+    {
+      "uri": "TriangleMeshopt.bin",
+      "byteLength": 80
+    },
+    {
+      "byteLength": 32,
+      "extensions": {
+        "EXT_meshopt_compression": {
+          "fallback": true
+        }
+      }
+    }
+  ],
+  "meshes": [
+    {
+      "primitives": [
+        {
+          "attributes": {
+            "POSITION": 1
+          },
+          "mode": 4,
+          "indices": 0
+        }
+      ]
+    }
+  ],
+  "nodes": [
+    {
+      "translation": [
+        0.5,
+        0.5,
+        0
+      ],
+      "scale": [
+        0.5,
+        0.5,
+        0.5
+      ],
+      "mesh": 0
+    }
+  ],
+  "scenes": [
+    {
+      "nodes": [
+        0
+      ]
+    }
+  ],
+  "scene": 0,
+  "extensionsUsed": [
+    "KHR_mesh_quantization",
+    "EXT_meshopt_compression"
+  ],
+  "extensionsRequired": [
+    "KHR_mesh_quantization",
+    "EXT_meshopt_compression"
+  ]
+}

specs/data/Triangle/TriangleMeshoptNoByteOffset.gltf

@@ -0,0 +1,123 @@
+{
+  "asset": {
+    "generator": "glTF-Transform v3.10.1",
+    "version": "2.0"
+  },
+  "accessors": [
+    {
+      "type": "SCALAR",
+      "componentType": 5123,
+      "count": 3,
+      "normalized": false,
+      "bufferView": 0
+    },
+    {
+      "type": "VEC3",
+      "componentType": 5122,
+      "count": 3,
+      "max": [
+        32767,
+        32767,
+        0
+      ],
+      "min": [
+        -32767,
+        -32767,
+        0
+      ],
+      "normalized": true,
+      "bufferView": 1
+    }
+  ],
+  "bufferViews": [
+    {
+      "buffer": 1,
+      "byteLength": 6,
+      "target": 34963,
+      "extensions": {
+        "EXT_meshopt_compression": {
+          "buffer": 0,
+          "byteLength": 18,
+          "mode": "TRIANGLES",
+          "byteStride": 2,
+          "count": 3
+        }
+      }
+    },
+    {
+      "buffer": 1,
+      "byteOffset": 8,
+      "byteLength": 24,
+      "target": 34962,
+      "byteStride": 8,
+      "extensions": {
+        "EXT_meshopt_compression": {
+          "buffer": 0,
+          "byteOffset": 20,
+          "byteLength": 60,
+          "mode": "ATTRIBUTES",
+          "byteStride": 8,
+          "count": 3
+        }
+      }
+    }
+  ],
+  "buffers": [
+    {
+      "uri": "TriangleMeshopt.bin",
+      "byteLength": 80
+    },
+    {
+      "byteLength": 32,
+      "extensions": {
+        "EXT_meshopt_compression": {
+          "fallback": true
+        }
+      }
+    }
+  ],
+  "meshes": [
+    {
+      "primitives": [
+        {
+          "attributes": {
+            "POSITION": 1
+          },
+          "mode": 4,
+          "indices": 0
+        }
+      ]
+    }
+  ],
+  "nodes": [
+    {
+      "translation": [
+        0.5,
+        0.5,
+        0
+      ],
+      "scale": [
+        0.5,
+        0.5,
+        0.5
+      ],
+      "mesh": 0
+    }
+  ],
+  "scenes": [
+    {
+      "nodes": [
+        0
+      ]
+    }
+  ],
+  "scene": 0,
+  "extensionsUsed": [
+    "KHR_mesh_quantization",
+    "EXT_meshopt_compression"
+  ],
+  "extensionsRequired": [
+    "KHR_mesh_quantization",
+    "EXT_meshopt_compression"
+  ]
+}