math

问题 I have a quaternion that contains the rotation of the three axes (x, y, z) at the same time. I want to convert this quaternion to a rotation matrix but only the rotation on the Y axis of the quaternion or of any of the other axes, without all three at the same time. 回答1: A possible route: Transform unit vectors X=(1,0,0) and Z=(0,0,1) by the quaternion Call these rotated vectors (x0,x1,x2) and (z0,z1,z2) If the rotation would have been purely around Y, we would have: (x0,x1,x2) = (cos(theta),

问题 I placed an accelerometer to several fishes in a field experiment to understand some of their behaviours. What I got was values of raw acceleration (X, Y, Z) of the fishes. This raw acceleration is decomposed into a part that is static (due to the gravity. I call it rmX , rmY and rmZ ) and a dynamic part (due to the movement of the fish. I call it diX , diY and diZ ). What I would like is to calculate the roll of my fishes in different circumstances (while swimming, resting, etc) since this

问题 I placed an accelerometer to several fishes in a field experiment to understand some of their behaviours. What I got was values of raw acceleration (X, Y, Z) of the fishes. This raw acceleration is decomposed into a part that is static (due to the gravity. I call it rmX , rmY and rmZ ) and a dynamic part (due to the movement of the fish. I call it diX , diY and diZ ). What I would like is to calculate the roll of my fishes in different circumstances (while swimming, resting, etc) since this

问题 Having been stuck on this for 4 days now, ive turned to the community for help. I am attempting to calculate the distance given from a point, given the angle off the wall, all distances to wall items are from the left. If dragging the item on wall A I know that I will need to track the mouse movement of the x axis If dragging the item on wall B I know that I will need to use a ratio of x and y to calculate the distance to the left If dragging the item on wall C I know that I will need to

问题 Apologies that I can't show code I'm just not sure how to go about this. I would like to achieve something like display: flex/grid does with fractions: Given a container width: 200px And items: [0.5, 1, 50px] I should be able to calculate the fractional ones relative to each other: item1: 50 (half the size of item 2) item2: 100 (double the size of item 1) item3: 50 (static size not a fraction) const totalSize = 900; const items = [1, 0.2, 75, 0.6, 1, 100]; const totalStaticSize = items.filter

问题 Apologies that I can't show code I'm just not sure how to go about this. I would like to achieve something like display: flex/grid does with fractions: Given a container width: 200px And items: [0.5, 1, 50px] I should be able to calculate the fractional ones relative to each other: item1: 50 (half the size of item 2) item2: 100 (double the size of item 1) item3: 50 (static size not a fraction) const totalSize = 900; const items = [1, 0.2, 75, 0.6, 1, 100]; const totalStaticSize = items.filter

问题 I'm trying to find out the angle of the triangle in the following, I know it should be 90 degrees, however I don't know how to actually calculate it in the following: Here's what I've tried: angle = math.cos(7/9.899) angleToDegrees = math.degrees(angle) returns: 43.XX What am I doing wrong? 回答1: It's a little more compicated than that. You need to use the law of cosines >>> A = 7 >>> B = 7 >>> C = 9.899 >>> from math import acos, degrees >>> degrees(acos((A * A + B * B - C * C)/(2.0 * A * B))

问题 I am trying to calculate the rotation of my device when I rotate it around the y-axis in ARKit. For clarification the y-axis in ARKit is the axis pointing upwards perpendicular to the ground. I used eulerangles to get the rotation of the camera like this: var alpha = sceneView.pointOfView?.eulerAngles.y This approximately works when 0=<alpha<pi/2 and when -pi/2<alpha<=0 , but for what is supposed to be other angles I get the wrong readings. I suspect this has to do with gimbal lock and that I

问题 I'm working on a code to do a software skinner (bone/skin animation), and I'm at the "optimization" phase (the skinner works pretty well and skin a 4900 triangles mesh with 22 bones in 1.09 ms on a Core Duo 2 Ghz (notebook)). What I need to know is : 1) Can someone show me the way (maybe with pseudocode) to transform a float3 (array of 3 float) (representing a coordinate) against a float4x3 matrix? 2) Can someone show me the way (maybe with pseudocode) to transform a float3 (array of 3 float)

问题 I'm working on a code to do a software skinner (bone/skin animation), and I'm at the "optimization" phase (the skinner works pretty well and skin a 4900 triangles mesh with 22 bones in 1.09 ms on a Core Duo 2 Ghz (notebook)). What I need to know is : 1) Can someone show me the way (maybe with pseudocode) to transform a float3 (array of 3 float) (representing a coordinate) against a float4x3 matrix? 2) Can someone show me the way (maybe with pseudocode) to transform a float3 (array of 3 float)