Say I have a model loaded in babylon.js. Say I want to calculate what is the gradient at any point of the model, for example the point that user clicks on. Is there a way to access the data of individual points, I guess the vertex or face etc where user clicks, and the surrounding ones to be able t…

@JohnK thank you very much John ,so if (p, p2 + q2, q ) is steepest ascent, which would be the steepest descent (which is the one i need), would it be just the opposite I guess: (-p, -(p2 + q2), -q ) and so, if I have: const gp=-Pdata[0]/Pdata[1]; const gq=-Pdata[2]/Pdata[1]; const Gradient = n…

[image] javismiles: would it be just the opposite I guess: (-p, -(p2 + q2), -q ) Yes [image] javismiles: if I want to set an arrow pointing in that direction, Possibly try Target Axes Alignment | Babylon.js Documentation

@JohnK thank you very much again John, your change in equation definitely seems to make things behave better yeah, and about rotation I’m going to investigate the " [Target Axes Alignment", although it seems that the const rx = Math.acos(dir._x/magnitudeGradient); const ry = Math.acos(dir._y/magn…

@JohnK I tried to use const orientation = Vector3.RotationFromAxis(-gp,-(gpgp+gqgq), -gq); myArrow.rotation = orientation; but I get error apparently because the parameters of RotationFromAxis should be: " where axis1 , axis2 and axis3 are three left-handed orthogonal vectors and the mesh will be…

[image] javismiles: magnitude of the gradient strength, which one of these would be the correct one to use? I would go with const gradmag1= Math.sqrt(Grad.x * Grad.x + Grad.y * Grad.y); This is equivalent to const gradmag1= Grad.length(); [image] javismiles: gradient vector to 3 left-…

A way of drawing an arrow in right place and direction plus scalable [image] Draw an arrow in 3d space, start and end of arrow flexible Questions An alternative to drawing and scaling an arrow. This way the arrow is created from given a start position and a direction htt…

Sry for disturbance. May I just say that I’m now eager to see the end result of all this. Will you share it? :smiley: You certainly raised my interest with your posts…

its all part of a larger project sure once it all comes together nicely it should be possible :wink:

@JohnK this is awesome John, I have some doubts posted them in the arrow thread :slight_smile:

@JohnK “The normal, N, the gradient vector G = (p, p2 + q2, q ) and (N cross G) form 3 orthogonal vectors. To get these to match you may have to play around with using (G cross N) rather than (N cross G) direction of one in in opposite to the other and setting y = N then play with x = G or z = G” I…

Accesing information of points in a model to calculate things like gradient etc

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JohnK January 25, 2021, 1:29pm 39

A way of drawing an arrow in right place and direction plus scalable

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Accesing information of points in a model to calculate things like gradient etc

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