d-ronnqvist
How to call glPointSize() (or the SceneKit equivalent) when making custom geometries using SceneKit and SCNGeometryPrimitiveTypePoint
I'm riffing off of Chapter 7, page 97 and have run into an issue I can't figure out. I've posted my question to SO as well, but will repost here. Thanks again for this great book @d-ronnqvist!
I'm writing an iOS app that renders a pointcloud in SceneKit using a custom geometry. This post was super helpful in getting me there (though I translated this to Objective-C), as was David Rönnqvist's book 3D Graphics with SceneKit (see chapter on custom geometries). The code works fine, but I'd like to make the points render at a larger point size - at the moment the points are super tiny.
According to the OpenGL docs, you can do this by calling glPointSize(). From what I understand, SceneKit is built on top of OpenGL so I'm hoping there is a way to access this function or do the equivalent using SceneKit. Any suggestions would be much appreciated!
My code is below. I've also posted a small example app on bitbucket accessible here.
// set the number of points
NSUInteger numPoints = 10000;
// set the max distance points
int randomPosUL = 2;
int scaleFactor = 10000; // because I want decimal points
// but am getting random values using arc4random_uniform
PointcloudVertex pointcloudVertices[numPoints];
for (NSUInteger i = 0; i < numPoints; i++) {
PointcloudVertex vertex;
float x = (float)(arc4random_uniform(randomPosUL * 2 * scaleFactor));
float y = (float)(arc4random_uniform(randomPosUL * 2 * scaleFactor));
float z = (float)(arc4random_uniform(randomPosUL * 2 * scaleFactor));
vertex.x = (x - randomPosUL * scaleFactor) / scaleFactor;
vertex.y = (y - randomPosUL * scaleFactor) / scaleFactor;
vertex.z = (z - randomPosUL * scaleFactor) / scaleFactor;
vertex.r = arc4random_uniform(255) / 255.0;
vertex.g = arc4random_uniform(255) / 255.0;
vertex.b = arc4random_uniform(255) / 255.0;
pointcloudVertices[i] = vertex;
// NSLog(@"adding vertex #%lu with position - x: %.3f y: %.3f z: %.3f | color - r:%.3f g: %.3f b: %.3f",
// (long unsigned)i,
// vertex.x,
// vertex.y,
// vertex.z,
// vertex.r,
// vertex.g,
// vertex.b);
}
// convert array to point cloud data (position and color)
NSData *pointcloudData = [NSData dataWithBytes:&pointcloudVertices length:sizeof(pointcloudVertices)];
// create vertex source
SCNGeometrySource *vertexSource = [SCNGeometrySource geometrySourceWithData:pointcloudData
semantic:SCNGeometrySourceSemanticVertex
vectorCount:numPoints
floatComponents:YES
componentsPerVector:3
bytesPerComponent:sizeof(float)
dataOffset:0
dataStride:sizeof(PointcloudVertex)];
// create color source
SCNGeometrySource *colorSource = [SCNGeometrySource geometrySourceWithData:pointcloudData
semantic:SCNGeometrySourceSemanticColor
vectorCount:numPoints
floatComponents:YES
componentsPerVector:3
bytesPerComponent:sizeof(float)
dataOffset:sizeof(float) * 3
dataStride:sizeof(PointcloudVertex)];
// create element
SCNGeometryElement *element = [SCNGeometryElement geometryElementWithData:nil
primitiveType:SCNGeometryPrimitiveTypePoint
primitiveCount:numPoints
bytesPerIndex:sizeof(int)];
// create geometry
SCNGeometry *pointcloudGeometry = [SCNGeometry geometryWithSources:@[ vertexSource, colorSource ] elements:@[ element]];
// add pointcloud to scene
SCNNode *pointcloudNode = [SCNNode nodeWithGeometry:pointcloudGeometry];
[self.myView.scene.rootNode addChildNode:pointcloudNode];
Pretty sure they’ve moved over to metal, especially on iOS. You may want to check on how to do it in Metal..
On Jul 7, 2016, at 5:45 PM, Abraham Avnisan [email protected] wrote:
I'm riffing off of Chapter 7, page 97 and have run into an issue I can't figure out. I've posted my question to SO http://stackoverflow.com/questions/38257339/how-to-call-glpointsize-or-the-scenekit-equivalent-when-making-custom-geomet as well, but will repost here. Thanks again for this great book @d-ronnqvist https://github.com/d-ronnqvist!
I'm writing an iOS app that renders a pointcloud in SceneKit using a custom geometry. This post http://stackoverflow.com/questions/32712268/how-to-use-scenekit-to-display-a-colorful-point-cloud-using-custom-scngeometry/38252032#38252032 was super helpful in getting me there (though I translated this to Objective-C), as was David Rönnqvist's book 3D Graphics with SceneKit http://scenekitbook.com/ (see chapter on custom geometries). The code works fine, but I'd like to make the points render at a larger point size - at the moment the points are super tiny.
According to the OpenGL docs, you can do this by calling glPointSize(). From what I understand, SceneKit is built on top of OpenGL so I'm hoping there is a way to access this function or do the equivalent using SceneKit. Any suggestions would be much appreciated!
My code is below. I've also posted a small example app on bitbucket accessible here https://bitbucket.org/abrahamavnisan/scenekitpointsize.
// set the number of points NSUInteger numPoints = 10000;
// set the max distance points int randomPosUL = 2; int scaleFactor = 10000; // because I want decimal points // but am getting random values using arc4random_uniform
PointcloudVertex pointcloudVertices[numPoints];
for (NSUInteger i = 0; i < numPoints; i++) {
PointcloudVertex vertex; float x = (float)(arc4random_uniform(randomPosUL * 2 * scaleFactor)); float y = (float)(arc4random_uniform(randomPosUL * 2 * scaleFactor)); float z = (float)(arc4random_uniform(randomPosUL * 2 * scaleFactor)); vertex.x = (x - randomPosUL * scaleFactor) / scaleFactor; vertex.y = (y - randomPosUL * scaleFactor) / scaleFactor; vertex.z = (z - randomPosUL * scaleFactor) / scaleFactor; vertex.r = arc4random_uniform(255) / 255.0; vertex.g = arc4random_uniform(255) / 255.0; vertex.b = arc4random_uniform(255) / 255.0; pointcloudVertices[i] = vertex; // NSLog(@"adding vertex #%lu with position - x: %.3f y: %.3f z: %.3f | color - r:%.3f g: %.3f b: %.3f", // (long unsigned)i, // vertex.x, // vertex.y, // vertex.z, // vertex.r, // vertex.g, // vertex.b);}
// convert array to point cloud data (position and color) NSData *pointcloudData = [NSData dataWithBytes:&pointcloudVertices length:sizeof(pointcloudVertices)];
// create vertex source SCNGeometrySource *vertexSource = [SCNGeometrySource geometrySourceWithData:pointcloudData semantic:SCNGeometrySourceSemanticVertex vectorCount:numPoints floatComponents:YES componentsPerVector:3 bytesPerComponent:sizeof(float) dataOffset:0 dataStride:sizeof(PointcloudVertex)];
// create color source SCNGeometrySource *colorSource = [SCNGeometrySource geometrySourceWithData:pointcloudData semantic:SCNGeometrySourceSemanticColor vectorCount:numPoints floatComponents:YES componentsPerVector:3 bytesPerComponent:sizeof(float) dataOffset:sizeof(float) * 3 dataStride:sizeof(PointcloudVertex)];
// create element SCNGeometryElement *element = [SCNGeometryElement geometryElementWithData:nil primitiveType:SCNGeometryPrimitiveTypePoint primitiveCount:numPoints bytesPerIndex:sizeof(int)];
// create geometry SCNGeometry *pointcloudGeometry = [SCNGeometry geometryWithSources:@[ vertexSource, colorSource ] elements:@[ element]];
// add pointcloud to scene SCNNode *pointcloudNode = [SCNNode nodeWithGeometry:pointcloudGeometry]; [self.myView.scene.rootNode addChildNode:pointcloudNode]; — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/d-ronnqvist/SCNBook-code/issues/17, or mute the thread https://github.com/notifications/unsubscribe/ABmgOnWE9hN58WXXOOAwIGPc9WeDn91lks5qTZ2_gaJpZM4JHobX.
Thanks for the prompt reply @drwave, I'll look into it and see what I can dig up!
pointcloudGeometry.firstMaterial.shaderModifiers = [SCNShaderModifierEntryPoint.geometry: "gl_PointSize = 2.5;"] Worked for me in simulator, but on ios device I got "Big Green Flashing Pixels"
