我以编程方式创建了一个完全自定义装配的 SCNNode。该节点包含自定义几何体、作为子节点层次结构的骨架装备和用于将骨架和几何体绑定在一起的 SCNSkinner 对象。问题是这样的：一旦我克隆了我的自定义节点，它就会失去几何和骨架之间的绑定。
为了找到这个问题的根源，我用我能想到的最简单的几何结构组合交换了我相当复杂的角色节点：12 个顶点的几何块和 3 个关节的骨架结构。
在这一点上，我很想分享一张图片，但因为我没有足够的声誉，所以不能这样做，但是......
-(SCNNode *)createCustomRigBlock {
// baseGeometry
SCNVector3 positions[] = {
SCNVector3Make(0, 0, 0),
SCNVector3Make(0, 0, 1),
SCNVector3Make(1, 0, 1),
SCNVector3Make(1, 0, 0),
SCNVector3Make(0, 1, 0),
SCNVector3Make(0, 1, 1),
SCNVector3Make(1, 1, 1),
SCNVector3Make(1, 1, 0),
SCNVector3Make(0, 2, 0),
SCNVector3Make(0, 2, 1),
SCNVector3Make(1, 2, 1),
SCNVector3Make(1, 2, 0)
};
SCNGeometrySource * baseGeometrySource = [SCNGeometrySource geometrySourceWithVertices:positions count:12];
typedef struct {
uint16_t a, b, c;
} Triangles;
Triangles tVectors[20] = {
0,1,2,
0,2,3,
0,1,5,
0,4,5,
4,5,9,
4,8,9,
1,2,6,
1,5,6,
5,6,10,
5,9,10,
2,3,7,
2,6,7,
6,7,11,
6,10,11,
3,0,4,
3,4,7,
7,4,8,
7,8,11,
8,9,10,
8,10,11
};
NSData *triangleData = [NSData dataWithBytes:tVectors length:sizeof(tVectors)];
SCNGeometryElement * baseGeometryElement = [SCNGeometryElement geometryElementWithData:triangleData primitiveType:SCNGeometryPrimitiveTypeTriangles primitiveCount:20 bytesPerIndex:sizeof(uint16_t)];
SCNGeometry * baseGeometry = [SCNGeometry geometryWithSources:[NSArray arrayWithObject:baseGeometrySource] elements:[NSArray arrayWithObject:baseGeometryElement]];
baseGeometry.firstMaterial.emission.contents = [UIColor greenColor];
baseGeometry.firstMaterial.doubleSided = YES;
baseGeometry.firstMaterial.transparency = 0.5;
SCNNode *customBlock = [SCNNode nodeWithGeometry:baseGeometry];
int stageSize = 30;
customBlock.position = SCNVector3Make(stageSize/2, 0, stageSize/2-6);
int vectorCount = (int)[(SCNGeometrySource *)[customBlock.geometry geometrySourcesForSemantic:SCNGeometrySourceSemanticVertex].firstObject vectorCount];
//bones ... the bones of the rig
NSMutableArray * bonesArray = [NSMutableArray new];
for (int i = 0; i < 3; i++) {
SCNNode * boneNode = [SCNNode new];
boneNode.name = [NSString stringWithFormat:@"bone_%i",i];
if (bonesArray.count > 0) {
[bonesArray.lastObject addChildNode:boneNode];
}
boneNode.position = SCNVector3Make((i>0 ? 0 : 0.5), (i>0 ? 0.75 : 0.25), (i>0 ? 0 : 0.5));
//add a sphere to each bone, to visually check its position etc.
SCNSphere *boneSphereGeom = [SCNSphere sphereWithRadius:0.1];
boneSphereGeom.firstMaterial.emission.contents = [UIColor redColor];
SCNNode * boneSphere = [SCNNode nodeWithGeometry:boneSphereGeom];
[boneNode addChildNode:boneSphere];
[bonesArray addObject:boneNode];
}
[customBlock addChildNode:bonesArray.firstObject];
//boneInverseBindTransforms ... this defines the geometries transformation in the default pose!
NSMutableArray * bibtArray = [NSMutableArray new];
for (int i = 0; i < 3; i++) {
SCNMatrix4 initialPositionMatrix = SCNMatrix4MakeTranslation(0.5, (i*0.75)+0.25, 0.5);
SCNMatrix4 inverseFinalMatrix = SCNMatrix4Invert(initialPositionMatrix);
NSValue * bibtValue = [NSValue valueWithSCNMatrix4:inverseFinalMatrix];
[bibtArray addObject:bibtValue];
}
//boneWeights ... the weights, at which each vertex is influenced by certain bones (which bones is defined by "boneIndices")
typedef struct {
float a, b, c;
} WeightVectors;
WeightVectors vectors[vectorCount];
for (int i = 0; i < vectorCount; i++) {
// set the same boneWeights for every vertex
vectors[i].a = 1;
vectors[i].b = 0;
vectors[i].c = 0;
}
NSData *weightData = [NSData dataWithBytes:vectors length:sizeof(vectors)];
SCNGeometrySource * boneWeightsGeometrySource = [SCNGeometrySource geometrySourceWithData:weightData
semantic:SCNGeometrySourceSemanticBoneWeights
vectorCount:vectorCount
floatComponents:YES
componentsPerVector:3
bytesPerComponent:sizeof(float)
dataOffset:offsetof(WeightVectors, a)
dataStride:sizeof(WeightVectors)];
//boneIndices
typedef struct {
short k, l, m; // boneWeight
} IndexVectors;
IndexVectors iVectors[vectorCount];
for (int i = 0; i < vectorCount; i++) {
if (i > 7) {
iVectors[i].k = 1;
iVectors[i].l = 0;
iVectors[i].m = 0;
} else {
iVectors[i].k = 0;
iVectors[i].l = 0;
iVectors[i].m = 0;
}
}
NSData *indexData = [NSData dataWithBytes:iVectors length:sizeof(iVectors)];
SCNGeometrySource * boneIndicesGeometrySource = [SCNGeometrySource geometrySourceWithData:indexData
semantic:SCNGeometrySourceSemanticBoneIndices
vectorCount:vectorCount
floatComponents:NO
componentsPerVector:3
bytesPerComponent:sizeof(short)
dataOffset:offsetof(IndexVectors, k)
dataStride:sizeof(IndexVectors)];
SCNSkinner * customBlockSkinner = [SCNSkinner skinnerWithBaseGeometry:baseGeometry
bones:bonesArray
boneInverseBindTransforms:bibtArray
boneWeights:boneWeightsGeometrySource
boneIndices:boneIndicesGeometrySource];
customBlock.skinner = customBlockSkinner;
[[bonesArray objectAtIndex:1] runAction:[SCNAction repeatActionForever:[SCNAction rotateByX:0 y:0 z:2 duration:2]]];
return customBlock;
}
只要我直接将它添加到我的场景中，这个自定义 SCNNode 就可以完美运行。现在，在我当前的应用程序中，我需要多次将此节点添加到场景中。这就是为什么我需要克隆节点并将生成的克隆添加到场景中。但是克隆自定义节点的结果是非常错误的。正如我上面提到的，几何和骨架之间的绑定似乎丢失了。克隆节点中的骨架仍然可以定位在我的场景中，但几何不再跟随骨架位置或变换。
我已经尝试过的：
1.) 我创建了一个新节点并向其添加了原始几何图形的副本。然后我克隆了骨架根节点并将其添加到新节点中。最后，我将原件剥皮器设置为新节点剥皮器。不幸无济于事。结果的行为与直接克隆的节点完全相同。
SCNNode * newNode = [SCNNode node];
newNode.geometry = [node.geometry copy];
for (SCNNode * childNode in node.childNodes) {
[newNode addChildNode:[childNode clone]];
}
newNode.skinner = node.skinner;
2.) 在尝试重新创建几何体和骨架之间的绑定时，我创建了 SCNSkinner 的深层副本，并使其成为新节点的蒙皮器。但这只会导致 C3DSourceAccessorGetMutableValuePtrAtIndex 崩溃，我无法修复。
NSArray * newBones = [newNode childNodesPassingTest:^(SCNNode *child, BOOL *stop)
{
if (![child.name isEqualToString:@"manipulator"] ) {
return YES;
}
return NO;
}];
NSArray * newBoneInverseBindTransforms = [node.skinner.boneInverseBindTransforms copy];
SCNGeometrySource * newBoneWeights = [SCNGeometrySource geometrySourceWithData:[node.skinner.boneWeights.data copy]
semantic:SCNGeometrySourceSemanticBoneWeights
vectorCount:node.skinner.boneWeights.vectorCount
floatComponents:node.skinner.boneWeights.floatComponents
componentsPerVector:node.skinner.boneWeights.componentsPerVector
bytesPerComponent:node.skinner.boneWeights.bytesPerComponent
dataOffset:node.skinner.boneWeights.dataOffset
dataStride:node.skinner.boneWeights.dataStride];
SCNGeometrySource * newBoneIndices = [SCNGeometrySource geometrySourceWithData:[node.skinner.boneIndices.data copy]
semantic:SCNGeometrySourceSemanticBoneIndices
vectorCount:node.skinner.boneIndices.vectorCount
floatComponents:node.skinner.boneIndices.floatComponents
componentsPerVector:node.skinner.boneIndices.componentsPerVector
bytesPerComponent:node.skinner.boneIndices.bytesPerComponent
dataOffset:node.skinner.boneIndices.dataOffset
dataStride:node.skinner.boneIndices.dataStride];
SCNSkinner * newSkinner = [SCNSkinner skinnerWithBaseGeometry:newNode.geometry
bones:newBones
boneInverseBindTransforms:newBoneInverseBindTransforms
boneWeights:newBoneWeights
boneIndices:newBoneIndices];
newNode.skinner = newSkinner;