我对使用Scene Kit感兴趣,但我的场景可能有数千个球体.压力测试Scene Kit我试过这个：
SCNSphere *sphere = [SCNSphere sphereWithRadius:0.5];for (int i=0; i<10; i++) { for(int j=0; j<10; j++){ for(int k=0; k<10; k++){ SCNNode *myNode = [SCNNode nodeWithGeometry:sphere]; myNode.position = SCNVector3Make(i,j,k); [root addChildNode:myNode]; } }} 这适用于1000球(10 ^ 3),但对1,000,000球(100 ^ 3)失败(也许不足为奇).我不介意不能使用一百万个球体,但我想弄清楚明智的上限是什么(5,000？15,000？)以及如何增加它.
我该怎么做才能缓解这种情况？例如我已经尝试过sphere.segmentCount = 3,虽然这会加速渲染,但它对内存使用没有太大影响,我怀疑这是限制因素.
此外,似乎没有SCNPoint类.我在考虑切换到仅在球体数量太高时显示一个点,但我无法从SceneKit文档中看到如何显示一个简单的点 – 我能看到的最简单的是一个三角形.
任何帮助深表感谢.
编辑：@toyos建议将SCNSphere对象合并到单个SCNGeometry对象中(前提是它们不需要独立动画,但它们不需要),但我找不到一种简单的方法来执行此 *** 作.
SCNGeometry是使用[SCNGeometry geometryWithSources：(* NSArray)sources geometryWithElements：(* NSArray)elements]创建的,如here所示,但我不清楚如何从我的球体创建SCNGeometry对象.
例如对于单个球体,我可以看到使用sphere.geometryElementCount来获取元素的数量,然后使用它来使用[sphere geometryElementAtIndex：(NSInteger)elementIndex]填充数组,这将给我元素,但我不知道如何得到“来源”(或他们甚至是什么).获取几何源的方法是[sphere geometrySourcesForSemantic：(Nsstring *)semantic],但这个语义字符串是什么？ (它意味着是“法线”还是“顶点”还是其他的东西？文档非常有用地说语义是“几何源的语义值.”而没有说出语义的可能值是什么)
这只是一个单一的球体,这是毫无意义的(因为SCNSphere只是SCNGeometry的一个子类),所以现在我必须添加多个球体.那么在将它们添加到我的SCNGeometry对象时,我是否必须手动转换球体的顶点？
我只想弄清楚最明智的做法.
解决方法 语义字符串是SCNGeometrySourceSemanticVertex | normal | Texcoord …对于多个球体,答案是肯定的,您必须在展平前使用当前节点变换变换顶点/法线.
下面是一个简化的例子(即它只支持合并“输入”的子项,如果它们都具有相同的几何)
- (SCNNode *) flattenNodeHIErarchy:(SCNNode *) input{ SCNNode *result = [SCNNode node]; NSUInteger nodeCount = [[input childNodes] count]; if(nodeCount > 0){ SCNNode *node = [[input childNodes] objectAtIndex:0]; NSArray *vertexArray = [node.geometry geometrySourcesForSemantic:SCNGeometrySourceSemanticVertex]; SCNGeometrySource *vertex = [vertexArray objectAtIndex:0]; SCNGeometryElement *element = [node.geometry geometryElementAtIndex:0]; //todo: support multiple elements NSUInteger primitiveCount = element.primitiveCount; NSUInteger newPrimitiveCount = primitiveCount * nodeCount; size_t elementBufferLength = newPrimitiveCount * 3 * sizeof(int); //nTriangle x 3 vertex * size of int int* elementBuffer = (int*)malloc(elementBufferLength); /* simple case: here we consIDer that all the objects to flatten are the same In the regular case we should iterate on every geometry and accumulate the number of vertex/triangles etc...*/ NSUInteger vertexCount = [vertex vectorCount]; NSUInteger newVertexCount = vertexCount * nodeCount; SCNVector3 *newVertex = malloc(sizeof(SCNVector3) * newVertexCount); SCNVector3 *newnormal = malloc(sizeof(SCNVector3) * newVertexCount); //assume same number of normal/vertex //fill NSUInteger vertexFillindex = 0; NSUInteger primitiveFillindex = 0; for(NSUInteger index=0; index< nodeCount; index++){ NSautoreleasePool *pool = [[NSautoreleasePool alloc] init]; node = [[input childNodes] objectAtIndex:index]; NSArray *vertexArray = [node.geometry geometrySourcesForSemantic:SCNGeometrySourceSemanticVertex]; NSArray *normalArray = [node.geometry geometrySourcesForSemantic:SCNGeometrySourceSemanticnormal]; SCNGeometrySource *vertex = [vertexArray objectAtIndex:0]; SCNGeometrySource *normals = [normalArray objectAtIndex:0]; if([vertex bytesPerComponent] != sizeof(float)){ NSLog(@"todo: support other byte per component"); continue; } float *vertexBuffer = (float *)[[vertex data] bytes]; float *normalBuffer = (float *)[[normals data] bytes]; CAtransform3D t = [node transform]; GLKMatrix4 matrix = MyGLKMatrix4FromCAtransform3D(t); //append source for(NSUInteger vIndex = 0; vIndex < vertexCount; vIndex++,vertexFillindex++){ GLKVector3 v = GLKVector3Make(vertexBuffer[vIndex * 3],vertexBuffer[vIndex * 3+1],vertexBuffer[vIndex * 3 + 2]); GLKVector3 n = GLKVector3Make(normalBuffer[vIndex * 3],normalBuffer[vIndex * 3+1],normalBuffer[vIndex * 3 + 2]); //transform v = GLKMatrix4MultiplyVector3WithTranslation(matrix,v); n = GLKMatrix4MultiplyVector3(matrix,n); newVertex[vertexFillindex] = SCNVector3Make(v.x,v.y,v.z); newnormal[vertexFillindex] = SCNVector3Make(n.x,n.y,n.z); } //append elements //here we assume that all elements are SCNGeometryPrimitiveTypeTriangles SCNGeometryElement *element = [node.geometry geometryElementAtIndex:0]; const voID *inputPrimitive = [element.data bytes]; size_t bpi = element.bytesPerIndex; NSUInteger offset = index * vertexCount; for(NSUInteger pIndex = 0; pIndex < primitiveCount; pIndex++,primitiveFillindex+=3){ elementBuffer[primitiveFillindex] = offset + _getIndex(inputPrimitive,bpi,pIndex*3); elementBuffer[primitiveFillindex+1] = offset + _getIndex(inputPrimitive,pIndex*3+1); elementBuffer[primitiveFillindex+2] = offset + _getIndex(inputPrimitive,pIndex*3+2); } [pool drain]; } NSArray *sources = @[[SCNGeometrySource geometrySourceWithVertices:newVertex count:newVertexCount],[SCNGeometrySource geometrySourceWithnormals:newnormal count:newVertexCount]]; NSData *newElementData = [NSMutableData dataWithBytesNocopy:elementBuffer length:elementBufferLength freeWhenDone:YES]; NSArray *elements = @[[SCNGeometryElement geometryElementWithData:newElementData primitiveType:SCNGeometryPrimitiveTypeTriangles primitiveCount:newPrimitiveCount bytesPerIndex:sizeof(int)]]; result.geometry = [SCNGeometry geometryWithSources:sources elements:elements]; //cleanup free(newVertex); free(newnormal); } return result;}//helpers:GLKMatrix4 MyGLKMatrix4FromCAtransform3D(CAtransform3D transform) { GLKMatrix4 m = {{transform.m11,transform.m12,transform.m13,transform.m14,transform.m21,transform.m22,transform.m23,transform.m24,transform.m31,transform.m32,transform.m33,transform.m34,transform.m41,transform.m42,transform.m43,transform.m44}}; return m;}GLKVector3 MySCNVector3ToGLKVector3(SCNVector3 vector) { GLKVector3 v = {{vector.x,vector.y,vector.z}}; return v;} 总结 以上是内存溢出为你收集整理的objective-c – OS X上的SceneKit,包含数千个对象全部内容，希望文章能够帮你解决objective-c – OS X上的SceneKit,包含数千个对象所遇到的程序开发问题。
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