我在尝试让带有纹理贴图的简单四边形在 iOS 模拟器上运行时遇到问题。我已经阅读了这里处理类似事情的所有其他问题，但我被卡住了。输出如下所示:

纹理是这样的:

我的代码是这样的:

  // v1 +----+ v0
  //    |    |
  // v2 +----+ v3



  SCNVector3 vertices[] = { SCNVector3Make(  5.0,  5.0, 0.0),
                            SCNVector3Make( -5.0,  5.0, 0.0),
                            SCNVector3Make( -5.0, -5.0, 0.0),
                            SCNVector3Make(  5.0, -5.0, 0.0)
  };

  SCNVector3 normals[] = { SCNVector3Make( 0.0f, 0.0f, 1.0),
                           SCNVector3Make( 0.0f, 0.0f, 1.0),
                           SCNVector3Make( 0.0f, 0.0f, 1.0),
                           SCNVector3Make( 0.0f, 0.0f, 1.0)
  };

  CGPoint textureCoordinates[] = { CGPointMake( 1.0, 1.0),
                                   CGPointMake( 0.0, 1.0),
                                   CGPointMake( 0.0, 0.0),
                                   CGPointMake( 1.0, 0.0)
  };

  NSUInteger vertexCount = 4;


  NSMutableData *indicesData = [NSMutableData data];
  UInt8 indices[] = { 0, 1, 2, 0, 2, 3};
  [indicesData appendBytes:indices length:sizeof(UInt8)*6];
  SCNGeometryElement *indicesElement = [SCNGeometryElement geometryElementWithData:indicesData
                                                                     primitiveType:SCNGeometryPrimitiveTypeTriangles
                                                                    primitiveCount:2
                                                                     bytesPerIndex:sizeof(UInt8)];

  NSMutableData *vertexData = [NSMutableData dataWithBytes:vertices length:vertexCount * sizeof(SCNVector3)];

  SCNGeometrySource *verticesSource = [SCNGeometrySource geometrySourceWithData:vertexData
                                                                       semantic:SCNGeometrySourceSemanticVertex
                                                                    vectorCount:vertexCount
                                                                floatComponents:YES
                                                            componentsPerVector:3
                                                              bytesPerComponent:sizeof(float)
                                                                     dataOffset:0
                                                                     dataStride:sizeof(SCNVector3)];

  NSMutableData *normalData = [NSMutableData dataWithBytes:normals length:vertexCount * sizeof(SCNVector3)];

  SCNGeometrySource *normalsSource = [SCNGeometrySource geometrySourceWithData:normalData
                                                                      semantic:SCNGeometrySourceSemanticNormal
                                                                   vectorCount:vertexCount
                                                               floatComponents:YES
                                                           componentsPerVector:3
                                                             bytesPerComponent:sizeof(float)
                                                                    dataOffset:0
                                                                    dataStride:sizeof(SCNVector3)];

  NSMutableData *textureData = [NSMutableData dataWithBytes:textureCoordinates length:vertexCount * sizeof(CGPoint)];

  SCNGeometrySource *textureSource = [SCNGeometrySource geometrySourceWithData:textureData
                                                                      semantic:SCNGeometrySourceSemanticTexcoord
                                                                   vectorCount:vertexCount
                                                               floatComponents:YES
                                                           componentsPerVector:2
                                                             bytesPerComponent:sizeof(float)
                                                                    dataOffset:0
                                                                    dataStride:sizeof(CGPoint)];
 SCNGeometry *geometry = [SCNGeometry geometryWithSources:@[verticesSource, normalsSource, textureSource]
                                                  elements:@[indicesElement]];


  SCNMaterial *material = [SCNMaterial material];
  //material.diffuse.contents = [UIColor redColor];
  material.diffuse.contents = [UIImage imageNamed:@"diffuse.jpg"];
  material.diffuse.wrapS = SCNWrapModeRepeat;
  material.diffuse.wrapT = SCNWrapModeRepeat;
  material.diffuse.contentsTransform = SCNMatrix4MakeScale( 1.0f, 1.0f, 1.0f);
  material.doubleSided = YES;

  material.normal.wrapS = SCNWrapModeRepeat;
  material.normal.wrapT = SCNWrapModeRepeat;
  //    material.litPerPixel = YES;

  geometry.materials = @[material];

[编辑] 我用这段代码尝试了很多不同的东西，但似乎没有任何效果。我还没有看到在 iOS 上运行的 Objective-C 中的工作示例。对 material.diffuse.wrapS 的任何更改均无效。

我以前在 OpenGL 中做过这种事情，没有任何问题，但我一直盯着这段代码看了好几天，看不出我的错误。非常感谢任何帮助。

最佳答案

@Paul-Jan 让我走上了正确的轨道，这让我得到了这个答案:

将我的纹理坐标从 CGPoint 更改为 float 可以修复它。

  float textureCoordinates[] = {  1.0, 1.0,
                                  0.0, 1.0,
                                  0.0, 0.0,
                                  1.0, 0.0
  };

  NSMutableData *textureData = [NSMutableData dataWithBytes:textureCoordinates length:vertexCount * sizeof(float) * 2];

  SCNGeometrySource *textureSource = [SCNGeometrySource geometrySourceWithData:textureData
                                                                      semantic:SCNGeometrySourceSemanticTexcoord
                                                                   vectorCount:vertexCount
                                                               floatComponents:YES
                                                           componentsPerVector:2
                                                             bytesPerComponent:sizeof(float)
                                                                    dataOffset:0
                                                                    dataStride:sizeof(float) * 2];

结果:

关于SceneKit 中的 iOS 自定义几何，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34478298/