Twist after tessellation triangle webgl3/25/2023 ![]() ![]() Here is my edited version summarising the results of that thread: With these necessary and powerful basics in place, I searched the Internet for a bit of help on implementing an algorithm to calculate the centroid, and found a discussion on determining the Polyhedron Centroid Calculation Algorithm This enables each boundary component of the solid or shell to be represented by a single properly closed triangulated structure. TessellateSolidOrShell method to facet an entire solid or open shell in one single call. This deficiency was eliminated by the SolidUtils class introduced in Revit 2013, which provides the Revit defines the approximation tolerance internally.Ĭalling it separately for neighbouring faces, however, will return independent triangulations that do not line up where the faces meet, leaving The Face.Triangulate method returns a triangular mesh approximation to the face. Happily, the Revit 2013 API provides a method for triangulating the entire surface of a solid in one single call, ensuring a closed volume, unlike doing it face by face, which does not. Gap Free Triangulation for Polyhedral Approximation If high precision is not paramount, however, we can simplify the solid to a planar faceted representation by triangulating all its faces to create aĭetermining the centroid of a polyhedron is something that can be achieved in a very few lines of code, as I will show below. Returning to the centroid and volume calculation, the Revit API provides both of these through the Solid ComputeCentroid method and Volume property.Īs said, a conversation prompted me to explore how to implement these calculations on my own as well.Ĭalculating exact results for an arbitrary solid is not trivial, of course, and could currently only be achieved making use of an external library. If you hook up these components intelligently, a lot of functionality can be achieved with little effort. He includes detailed explanations of the kind of problems this software addresses, getting started, and comparisons with other technologies such as the wind tunnel feature inīy the way, this is extremely interesting to look at for any Revit add-in developer, even if you do not care about this specific kind of analysis, because it shows an impressive example of using Revit as a front-end input tool to a powerful analysis component, reporting the results back graphically using the analysis visualisation framework AVF. Project Falcon is an outdoor airflow simulation add-in for Revit: Polyhedron centroid calculation implementationīefore getting into that, here is a quick heads-up to point out a new free technology preview to simulate airflow around buildings or other objects in a virtual wind tunnel: Project Falcon Computational Fluid Dynamics CFD Add-in.Revit implementation and CentroidVolume class.Polyhedron centroid calculation algorithm.Gap free triangulation for polyhedral approximation.Revit API centroid and volume calculation methods.Once again, that led to the exploration of a number of interesting little sub-topics: ![]() One of the many interesting conversations I had at Autodesk University that caught my special attention dealt with a simple geometrical Revit API question geometrical questions are among my favourites, and this one is really basic: how to calculate the I had a nap in the taxis to and from the airport yesterday, both in Germany and Sweden, so I was able to burn some midnight oil to share the following exploration with you. Today and tomorrow we spend in Gothenburg on the last lap of our journey, after Paris, Milano, Farnborough and Munich. Gl.drawArrays( gl.TRIANGLES, 0, points.I have not posted anything since last Friday, being too caught up in the West European Developer days and travelling. ThetaLoc = gl.getUniformLocation( program, "theta" ) įunction divideTriangle( a, b, c, count ) Gl.vertexAttribPointer( vPosition, 2, gl.FLOAT, false, 0, 0 ) Var vPosition = gl.getAttribLocation( program, "vPosition" ) Associate our shader variables with our data buffer Gl.bufferData( gl.ARRAY_BUFFER, flatten(points), gl.STATIC_DRAW ) Gl.bindBuffer( gl.ARRAY_BUFFER, bufferId ) Var program = initShaders( gl, "vertex-shader", "fragment-shader" ) Load shaders and initialize attribute buffers Gl.viewport( 0, 0, canvas.width, canvas.height ) First, initialize the corners of our gasket with three points.ĭivideTriangle( vertices, vertices, vertices, Initialize our data for the Sierpinski Gasket your browser doesn't support the HTML5 canvas elementĬanvas = document.getElementById( "gl-canvas" ) Gl_Position.y = s * vPosition.x + c * vPosition.y Gl_Position.x = -s * vPosition.y + c * vPosition.x ![]() How can I rotate the individual triangles? Currently, it rotates the entire tessellation as if it is one object. The purpose of my code is to individually rotate the four triangles that make up a tessellated triangle. ![]()
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