Question

我使用SceneKit显示.obj文件。但是要获取.obj文件，我使用来自传感器的SDK，因此该传感器扫描一个人的手臂并返回.obj文件。但是当我加载.obj文件时，有很多不合适的部分（椅子的一部分，表面的一部分等），我需要删除对象的这些部分，因此我只能看到男人的手臂。

例如，我想选择一个矩形或一个球体，并删除该球体中的所有顶点和面。

iOS中是否有任何SDK或框架可以做到这一点？

P.S。我尝试了nineveh和其他一些框架，但他们只能查看对象，他们无法编辑它们。

修改

我在SceneKit中找到了操纵顶点（它合并来自不同子节点的顶点）的代码。 我是否可以使用相同的方法来查找我需要删除的顶点（位于我的矩形内），或者使用65 K顶点时它会非常慢？

＆＃13;

//
//  VertexManager.m
//  Test
//

#import "VertexManager.h"
#import <SceneKit/SceneKit.h>
#import <GLKit/GLKit.h>

@implementation VertexManager

+ (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++){
            
            @autoreleasepool {
                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];
                
                SCNMatrix4 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, bpi, pIndex*3+1);
                    elementBuffer[primitiveFillIndex+2] = offset + _getIndex(inputPrimitive, bpi, pIndex*3+2);
                }
            }

        }
        
        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(SCNMatrix4 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;
}

@end

＆＃13;

Answer 1

没有。您将要使用Blender，Maya，3ds Max或Cheetah 3D等3D工具。

iOS从.obj文件中删除面和顶点

1 个答案: