# Tagged Questions

A branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.

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### LibGDX - Trying to make a radar-like display

i have an interesting question about geometry. I have two or more moving objects outside of my stage's viewport (blue and red circle in the image below), which i want to point at with two arrows on ...
26 views

### Check if a 3D mesh is a rectangular prism

I have a mesh post-processor in Unity that automatically a convex mesh collider to objects that need one (mostly all). Sometimes however there are objects that only need a box collider instead. ...
140 views

### Could triangles be used for swept-AABB checks between positions?

I'm trying to understand swept-AABB collision detection. When checking for collisions between two positions of an object, I commonly see one of 3 strategies used: Rays: trace rays from parts of the ...
42 views

### How to find a point on a plane?

I'm using unreal engine 4. Currently I ray trace to a surface in game and I'm trying to find the location of the point relative to the surface1 instead of the world. I have the world position of the ...
105 views

### Why is this unity camera moving in weird directions?

I have the following script public class CameraScript : MonoBehaviour { public bool AllowZoom; public float zoom; public float Speed; Transform board; void Start(){ ...
133 views

### Dual Contouring - Finding the feature point, normals off

I am following this tutorial to implement Dual Contouring http://www.sandboxie.com/misc/isosurf/isosurfaces.html My data source is a grid 16x16x16; I traverse this grid bottom to top, left to right, ...
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### What is the formula for the collision of two “stretched spheres”?

In Smash Bros Melee, hitboxes aren't perfect spheres or boxes. They are, instead, a shape that looks like a continuous line of consecutive spheres: I.e., the geometry can represented as: Hitbox :...
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### Rotate perspective camera to align screen width to procedural object's width (Unity, C#)

I give up. After much trying and searching, I have to say I was unable to achieve the following task, for which I must call for your wise advice. In my current Unity 5 application (using C#), there ...
370 views

### How to trace contour of shapes with holes?

I am experimenting with the RVO2 library for collision avoidance in a 2D simulation. This library supports specifying arbitrary obstacles as a list of vertices. The obstacles must be full shapes, i.e. ...
25 views

### HLSL topology mismatch question

I'm trying to write a fur shader with the shells & fins technique. Currently I receive this DirectX error D3D11 ERROR: ID3D11DeviceContext::DrawIndexed: The declared input primitive type in ...
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### 2d grid vision(eye sensor) for a neural network bot?

I have a 2d grid and neural network bots living above it. What is a good way to give them vision of tiles in front of them? Below I describe my idea that I don't know how to efficiently(or ...
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### Detecting the two Vector3 that determine the bottom-edge of the side of a box-collider that had collision (with C#)

So, I understand that plenty of questions have been posted on how to detect which side of a Box Collider had collision. However, what I am trying to achieve is a little different. I want to find out, ...
140 views

### Calculating Minimum Translation Vector in Separating Axis Theorem based algorithm

In the 2D SAT collision determination algorithm, you project the convex polygons onto each potential separating axis. Supposing the polygons intersect, from what I understand, the axis for which the ...
116 views

### How can I keep vertex order the same on every Instantiate()?

While trying to resolve another question, I have discovered that if I Instantiate() from a prefab, the order of the mesh vertices (and therefore triangles) is inconsistent between instances. This is ...
66 views

### Blender: calculation of elevation and rotation angle from plane

I have a generic plane (any location, any rotation around every axis) with its normal axis passing by the center. Then I have a generic point and I need to find the elevation and the rotation angle ...
20 views

### Rotating a UI arrow according to the change in camera's rotation

I have been trying different alternatives to do what is a very basic thing but I couldn't have any success. What I want to do is this. I have a 2D UI sprite at the screen, formed by 2 triangles, with ...
25 views

### Finding minimum horizontal offset to disjoin two objects in 3D

This is an extension of sorts of the question asked here: Allowing a player to walk up and down slopes without resistance I am using the Separating Axis Theorem to determine the minimum translation ...
28 views

### How to convert Non-Axis Aligned Bounding Boxes to AABB

I'm trying to write a raytracer to render boxes (cubes) that are arbitrarily rotated, i.e. not necessarily axis aligned. While I'm reasonably comfortable ray-tracing an axis-aligned cube, I don't know ...
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### How to find visible planes in a world of boxes

I have a world where each object is a box: Each box has position x, y=0, z, dimensions width, height, depth. The boxes are never rotated. Each box is composed of 5 planes (left, right, front, back ...
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### How to generate tangent and binormal(bitangent) of a triangle polygon mesh

I am currently using FBX sdk to acquire mesh information from obj and fbx files. However, not all meshes contain tangent and binormal(bitangent) information so I have to use the method ...
31 views

### Drawing shapes within a rectangle area

I am working on a Objective-c project where I need to draw multiple rectangle shapes inside a rectangle area like the attached image. Basically calculating CGPoints inside the CGRect. Thanks in ...
70 views

### Project 2d click/touch onto 3d plane

I have a 3d scene that contains an infinite plane that is NOT parallel to the camera (so every screen coordinate corresponds to a point on this plane- in other words, there are no possible invalid ...
41 views

### boost/geometry replacement in Java/for the JVM (Destructable Box2D terrain)

I'd like to reimplement https://github.com/seemk/DestructibleBox2D in Java. The main problem is finding an adequate replacement for the boost/geometry library. Any ideas?
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### 3D Picking: Doesn't Work Consistently

I'm trying to implement a 3D picking function that at the moment simply calculates the ray being sent from the camera after the user clicks the mouse on the window. It kind of works well when the ...
273 views

### Taking a 2D slice of a 3D volume

I have a regular 3D polygon and I'd like to display 2D slices of it. What is the best way to achieve this? (Preferrably in OpenGL, but a general algorithm/tecnique would be good as well). I've ...
37 views

### Rotating between two coordinate frames

I have two coordinate frames, A and B. I want to create the rotation matrix RAB which takes you from A to B. A is a right-handed system, and B is a left-handed system. Furthermore, after moving from a ...
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I've seen this video: all the geometry seems to grow and become fat. Nice effect. I'm just approaching the shader matter, and I'm still have to learn a lot about how to change geometry via shaders. ...
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### Calculation technique for 2D inertia tensors?

Just wondering what the techniques are out there. It's only 2D so I figured there'd be a good chance for there to be a "one size fits all" solution out there that's essentially an analytical solution. ...