Added support for non-indexed meshes in glTF importer. Addresses issue #2046.

code/glTF2Importer.cpp

@@ -521,6 +521,79 @@ void glTF2Importer::ImportMeshes(glTF2::Asset& r)
                     ai_assert(CheckValidFacesIndices(faces, nFaces, aim->mNumVertices));
                 }
             }
+            else { // no indices provided so directly generate from counts
+                aiFace* faces = 0;
+                unsigned int nFaces = 0;
+
+                // use the already determined count as it includes checks 
+                unsigned int count = aim->mNumVertices;
+
+                switch (prim.mode) {
+                case PrimitiveMode_POINTS: {
+                    nFaces = count;
+                    faces = new aiFace[nFaces];
+                    for (unsigned int i = 0; i < count; ++i) {
+                        SetFace(faces[i], i);
+                    }
+                    break;
+                }
+
+                case PrimitiveMode_LINES: {
+                    nFaces = count / 2;
+                    faces = new aiFace[nFaces];
+                    for (unsigned int i = 0; i < count; i += 2) {
+                        SetFace(faces[i / 2], i, i + 1);
+                    }
+                    break;
+                }
+
+                case PrimitiveMode_LINE_LOOP:
+                case PrimitiveMode_LINE_STRIP: {
+                    nFaces = count - ((prim.mode == PrimitiveMode_LINE_STRIP) ? 1 : 0);
+                    faces = new aiFace[nFaces];
+                    SetFace(faces[0], 0, 1);
+                    for (unsigned int i = 2; i < count; ++i) {
+                        SetFace(faces[i - 1], faces[i - 2].mIndices[1], i);
+                    }
+                    if (prim.mode == PrimitiveMode_LINE_LOOP) { // close the loop
+                        SetFace(faces[count - 1], faces[count - 2].mIndices[1], faces[0].mIndices[0]);
+                    }
+                    break;
+                }
+
+                case PrimitiveMode_TRIANGLES: {
+                    nFaces = count / 3;
+                    faces = new aiFace[nFaces];
+                    for (unsigned int i = 0; i < count; i += 3) {
+                        SetFace(faces[i / 3], i, i + 1, i + 2);
+                    }
+                    break;
+                }
+                case PrimitiveMode_TRIANGLE_STRIP: {
+                    nFaces = count - 2;
+                    faces = new aiFace[nFaces];
+                    SetFace(faces[0], 0, 1, 2);
+                    for (unsigned int i = 3; i < count; ++i) {
+                        SetFace(faces[i - 2], faces[i - 1].mIndices[1], faces[i - 1].mIndices[2], i);
+                    }
+                    break;
+                }
+                case PrimitiveMode_TRIANGLE_FAN:
+                    nFaces = count - 2;
+                    faces = new aiFace[nFaces];
+                    SetFace(faces[0], 0, 1, 2);
+                    for (unsigned int i = 3; i < count; ++i) {
+                        SetFace(faces[i - 2], faces[0].mIndices[0], faces[i - 1].mIndices[2], i);
+                    }
+                    break;
+                }
+
+                if (faces) {
+                    aim->mFaces = faces;
+                    aim->mNumFaces = nFaces;
+                    ai_assert(CheckValidFacesIndices(faces, nFaces, aim->mNumVertices));
+                }
+            }
 
 
             if (prim.material) {

code/glTFImporter.cpp

@@ -426,6 +426,79 @@ void glTFImporter::ImportMeshes(glTF::Asset& r)
                     ai_assert(CheckValidFacesIndices(faces, nFaces, aim->mNumVertices));
                 }
             }
+            else { // no indices provided so directly generate from counts
+                aiFace* faces = 0;
+                unsigned int nFaces = 0;
+
+                // use the already determined count as it includes checks 
+                unsigned int count = aim->mNumVertices;
+
+                switch (prim.mode) {
+                case PrimitiveMode_POINTS: {
+                    nFaces = count;
+                    faces = new aiFace[nFaces];
+                    for (unsigned int i = 0; i < count; ++i) {
+                        SetFace(faces[i], i);
+                    }
+                    break;
+                }
+
+                case PrimitiveMode_LINES: {
+                    nFaces = count / 2;
+                    faces = new aiFace[nFaces];
+                    for (unsigned int i = 0; i < count; i += 2) {
+                        SetFace(faces[i / 2], i, i + 1);
+                    }
+                    break;
+                }
+
+                case PrimitiveMode_LINE_LOOP:
+                case PrimitiveMode_LINE_STRIP: {
+                    nFaces = count - ((prim.mode == PrimitiveMode_LINE_STRIP) ? 1 : 0);
+                    faces = new aiFace[nFaces];
+                    SetFace(faces[0], 0, 1);
+                    for (unsigned int i = 2; i < count; ++i) {
+                        SetFace(faces[i - 1], faces[i - 2].mIndices[1], i);
+                    }
+                    if (prim.mode == PrimitiveMode_LINE_LOOP) { // close the loop
+                        SetFace(faces[count - 1], faces[count - 2].mIndices[1], faces[0].mIndices[0]);
+                    }
+                    break;
+                }
+
+                case PrimitiveMode_TRIANGLES: {
+                    nFaces = count / 3;
+                    faces = new aiFace[nFaces];
+                    for (unsigned int i = 0; i < count; i += 3) {
+                        SetFace(faces[i / 3], i, i + 1, i + 2);
+                    }
+                    break;
+                }
+                case PrimitiveMode_TRIANGLE_STRIP: {
+                    nFaces = count - 2;
+                    faces = new aiFace[nFaces];
+                    SetFace(faces[0], 0, 1, 2);
+                    for (unsigned int i = 3; i < count; ++i) {
+                        SetFace(faces[i - 2], faces[i - 1].mIndices[1], faces[i - 1].mIndices[2], i);
+                    }
+                    break;
+                }
+                case PrimitiveMode_TRIANGLE_FAN:
+                    nFaces = count - 2;
+                    faces = new aiFace[nFaces];
+                    SetFace(faces[0], 0, 1, 2);
+                    for (unsigned int i = 3; i < count; ++i) {
+                        SetFace(faces[i - 2], faces[0].mIndices[0], faces[i - 1].mIndices[2], i);
+                    }
+                    break;
+                }
+
+                if (faces) {
+                    aim->mFaces = faces;
+                    aim->mNumFaces = nFaces;
+                    ai_assert(CheckValidFacesIndices(faces, nFaces, aim->mNumVertices));
+                }
+            }
 
 
             if (prim.material) {