iOS Custom Geometry in SceneKit

Question

I am having trouble trying to get a simple quad with a texture map to run on the iOS Simulator. I have read all other questions on here which deal with similar things and I am stuck. The output looks like this:

The texture is this:

My code is this:

  // 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];

[Edit] I have tried many different things with this code and nothing seems to work. I am yet to see a working example in Objective-C that works on iOS. Any changes to material.diffuse.wrapS has no effect.

I have done this kind of thing in OpenGL before without any issue, but I have been staring at this code for days and can't see my mistake. Any help would be really appreciated.

Isn't a CGFloat a double on 64 bits iOS? You specify sizeof(float) for the byesPerComponent of the textureSource. — Paul-Jan
No difference unfortunately, just tried it. Thanks for very quick reply though. — Brett
@Paul-Jan See my answer below, when I tried your suggestion, I only changed it in the textureSource and not in the textureData. Looked at it again and changed in both places and it worked. If you want to write it as an answer I will accept that, otherwise I will accept my own answer. — Brett

Brett Brett · Accepted Answer · 2015-12-28T01:26:56

@Paul-Jan put me on the right track, which lead me to this answer:

Changing my texture coordinates from CGPoint to float fixes it.

  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];

Result:

iOS Custom Geometry in SceneKit

1 Answers