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Questions tagged [geometry]

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

2
votes
3answers
151 views

Get closest point on box to line

Eventually this problem will be 3D, so I would like a solution that works in 3D. My player is looking forwards. There is an axis-aligned box on the screen (FOV is guaranteed to be 90, so boxes behind ...
0
votes
1answer
50 views

Push cube outside triangle face

I'm creating a 3D game, and I need to know how to push a player (axis aligned box/cube) outside a triangle. How can I get get the push direction?
0
votes
1answer
34 views

Calculating approximations of contact between two meshes

I'm looking for ways to calculate the degree of contact between two objects in a scene. I was thinking that calculating the hausdorff distance would be a useful approximation if it is then normalized ...
-1
votes
1answer
79 views

Convert 3D direction vectors to yaw/pitch/roll angles

I have the code below that takes a set of yaw, pitch, and roll rotation angles (in degrees), and populates forward, right, and up basis vectors to express this rotated orientation as a Cartesian ...
2
votes
1answer
81 views

Click on an isometric plane and obtain normal coordinates

I have photos distributed as cells. When I click, I get the corresponding row and column. console.log("Col:" + X + "Row:" + Y); When applying an isometric view conversion like this: ctx.translate(0, ...
1
vote
1answer
50 views

How can I build an array of coordinates of a truncated icosahedron's faces?

I can easily get a list of coordinates of all the vertices—the Wikipedia page has formulae and this page has a list of them, but that doesn't tell me which ones are part of which face. What I'd like ...
0
votes
0answers
16 views

Moving and rotating object with another object [duplicate]

Sorry i bad painter)) Need move and rotate 'OBJECT №2' with 'OBJECT №1' I have origin point(also rotation point) and angles of two object. (Also min and max coordinates of these objects) Vector ...
1
vote
1answer
68 views

Move and rotate one object to another C++ [3D]

I have two object, need attach 'TWO OBJECT' to 'ONE OBJECT'. I have vectors 'angle' 'origin' of ONE and TWO objects. I tried do "TWOOBJECT.origin += ONE.origin - ONE.oldorigin", this just attach ...
-1
votes
1answer
66 views

How to detect least distance to line segments calculation

I'm trying to calculate the distance of the player to a few lines that intersect two points, and return the smallest distance (i.e. tell me which of the lines the player is closest to/how far the ...
4
votes
2answers
279 views

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 ...
1
vote
2answers
1k views

How to rotate a local position offset based on a direction vector?

I'm trying to fire three raycasts in the direction of movement, from offset starting points. I'm having trouble calculating the start positions of the rays based on the direction. As you can see in ...
3
votes
2answers
262 views

Shrink a convex polygon

Shrinking a concave polygon is quite hard, to do well. But I expect shrinking a convex polygon would be easy. The naive approach of moving each vertex a certain distance to the centre gives me poor ...
0
votes
1answer
19 views

Get the mesh Project Plane on Click and calculate its area

Here is the excerpt of my script which is calculating the surface area and face area of a mesh on OnMouseDown Event. ...
0
votes
1answer
83 views

Get triangles after subdivision

I was able to do subdivision on a triangle mesh with midpoints but then I get polygons with too many faces. How do I convert to triangles after? Similar to this picture:
0
votes
2answers
351 views

which quarter of a triangle the point is in

I've got a world made out of squares. The square are devided in four triangles like this: The corners have their heights stored in a 2D array and the center height is the average of the corners. To ...
0
votes
1answer
389 views

Overlap color between objects

I'm currently trying to build a game with Ogre3D that is basically a moving vehicle that leaves a green trail (2D manual mesh) in it's path, what i'm trying to achieve is exactly what this image shows:...
2
votes
2answers
181 views

Most efficient way to get the closest point to a 3d rectangle

I have a 3D rectangle, with 4 points (x,y,z) And I have a player, who can be anywere (inside the rectangle, outside, not even in the plane, in the corner...). I would like to get the closest point in ...
1
vote
0answers
60 views

algorithm to change the center of the image

I need and algorithm in Java if possible to change the center of the image when scaling.What is happening to me is represented in the first image: when I scale the image the image scale according to ...
0
votes
2answers
42 views

Unity3D - Generate a position within a circular band around the player

Given a certain condition in my game I need to generate a position around the player. It needs to be at least 8 meters away from him and within 10 meters, in a circular matter, as in the dotted green ...
0
votes
0answers
10 views

Object's plane on image

I have a segmented image. So, for example, I know 2D coordinates of pixels for road on image. Now I want to know a plane of this road. How can I do this? P.S. I think it's popular problem, so I'm ...
0
votes
1answer
32 views

Calculating surface normal numerically

Say I have a 2D surface defined with the use of bitmap. I want to use this bitmap for collision detection (white color is where object can move freely, with black I mark the walls). How can I ...
1
vote
2answers
418 views

Getting the bounding box of a sphere

I have a sphere with values center,radius and I need to convert the sphere to a bounding box with values min,max. How do I ...
0
votes
1answer
72 views

Get a Jump normal gravity based on Attractor Points, lines or Quad placed in the Level Design (in a Mario galaxy like gravity)

I have an algorithme to find. I have a player in a 3D space on a random planet. My goal is to have an oriented gravity toward my planet. And when I jump: Find the right normal direction. BUT I can't ...
0
votes
0answers
54 views

Getting the Closet Points between Polygons with the GJK Algorithm

I am trying to implement the GJK algorithm by following this lecture. For the most part, it is working, but sometimes 1 of the 2 closest points is incorrect. Here are two examples: EXAMPLE 1: The ...
0
votes
0answers
123 views

Find transformation to align two polygons at fixed points?

Problem I have a source image (arbitrary width and height c) shown here as a rectangle [X1,X2,X3,X4]. It contains two points C and D (both known coordinates within ...
2
votes
1answer
76 views

How to determine polygon based on point lists?

I have several lists of interconnected points. They are ordered so I can connect them together. Using these interconnected points I'd like to find the different points and intersection points that ...
0
votes
0answers
20 views

Is it possible to generate a 2D surface that approaches certain mesh, and then a specialised ray-tracing function for it?

As an example, suppose we are trying to ray-trace a sphere. There are two options. The first one is to build a mesh of triangles approximating the sphere and ray trace it. Unfortunately, the more ...
1
vote
3answers
326 views

exact point on a rotating sphere

I have a sphere that represents the Earth textured with real pictures. It's rotating around the x axis, and when user click down it has to show me the exact place he clicked on. For example if he ...
0
votes
1answer
36 views

Interpreting focal length in units of pixels

I am working on a renderer of sorts and I have some fundamental questions. Let's say I have a vector in a 3D virtual world space which is unitless, and I want to project it onto a 2D screen, so I need ...
4
votes
2answers
942 views

How can I mask this CanvasRenderer?

I'm creating a text box that allows for selectable text, based off of Unity's InputField. An issue I am now facing is that the selection highlight does not respond to masks (The parent has a mask, but ...
0
votes
3answers
105 views

How can you tell if you are a large player on a large map or a small player on a small map?

If everything is scaled by a constant factor, can you tell that the world is smaller or larger? I think you could look down at the ground and see that it's "closer". But how do you know what ...
0
votes
1answer
51 views

How to implement level-player collisions resolution?

I want to create simple collision response system (physical simulation is not required now). It is needed just that player can't go through walls. I consider some variants: - Just create a set of ...
0
votes
1answer
835 views

How to calculate the surface area of a mesh

I am looking for a way to calculate surface area of a 3D mesh object and found this code from a Unity forum: ...
2
votes
1answer
76 views

How can I express Logarithmic and Arithmetic spirals as segmented cubic bezier curves?

I am creating cubic bezier curves using this code from another question I asked. I would like to know how I can express Logarithmic and Arithmetic spirals as segmented cubic bezier curves.
2
votes
1answer
70 views

How to inflate geometry?

I have a shape containing vertices and triangles I want to inflate that geometry using some radius to get something like that I should move each point along ...
31
votes
1answer
8k views

How do you turn a cube into a sphere?

I'm trying to make a quad sphere based on an article, which shows results like this: I can generate a cube correctly: But when I convert all the points according to this formula (from the page ...
5
votes
1answer
411 views

Why are spherical worlds so rare?

I remember back in the 90s when X-Com came out, being really impressed by the way its world map was an actual world: a map of Earth drawn on a spherical surface. That was pretty cool, because I had ...
0
votes
1answer
92 views

Confused by scaling, units, and more

Ok, so I've already waded through a bunch of questions around this, and it's just making me even more confused. Let's say I am trying to model a card table in a 2d game. Behind (beneath) the table ...
0
votes
1answer
64 views

Define a circle from a point on its circumference and an angle

I'm working on a 2D, top-down driving game with some basic AI vehicles. The AI Vehicles move along a bidirected graph of positions. Each vehicle has a current position (from the graph) and a target ...
0
votes
1answer
36 views

Determine view-matrix with camera placed in a scene graph

My scene is organized with a simple scene graph where the child multiplies its transformation with the one of the parent. For normal objects, likes meshes, this works as expected, but I also want to ...
3
votes
1answer
259 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 ...
5
votes
2answers
4k views

What is a good way to determine if a vector is between two other vectors in 2D?

I could operate with the angles, but I do not have the angles calculated yet (and would like to avoid having to do that). It would be possible to calculate and cache the local-coordinate-frame angles, ...
9
votes
4answers
5k views

How do I efficiently check if a point is inside a rotated rectangle?

Part for the sake of optimization, part for learning purposes, I will dare to ask: How can I most efficiently check whether a 2D point P is inside a 2D rotated ...
2
votes
1answer
2k views

How do I calculate the distance between a point and a rotated rectangle?

This question is similar to another one about axis-aligned rectangles. However, I specifically want to calculate this for rotated rectangles. I have a rectangle with a (cx, cy) for the center point ...
1
vote
3answers
339 views

What's the most efficient way to find the position of a point in relation to corners of a rectangle despite rectangle's scale

I am struggling to achieve the following with C# (in Unity). I need to find the position of the points that lay at a given distance (let's say 1m) from the corners of a rectangle, in a way that the ...
11
votes
4answers
446 views

How do I interpolate around a rectangle?

I want to make a fancy animation where a point travels around a rectangle. I want to find the point's position at a time t. The rectangle is given by ...
0
votes
3answers
445 views

How to find the total bounds rectangle around a list of rectangles

How can I find the total bounds rectangle around a list of rectangles? Rectangle object: a simple data structure of 4 floats (w,h,x,y). I have an array of 2 or more rectangles and want to create a ...
3
votes
3answers
423 views

Divide rectangular image into fixed number of random sized rectangles + 1 fixed size rectangle

I'm trying to divide a rectangular image into a fixed number of smaller rectangular image parts (of random but bounded width / height), with the exception of 1 rectangle which is predefined in ...
2
votes
1answer
2k views

Get screen bounds of 3D object

I'm trying to draw a 2D plane that has minimum dimensions to contain a 3D model (a sphere). How do I calculate the minimum size and position of the rectangle to completely cover a 3D model on screen?
0
votes
0answers
43 views

Tetrahedron Circumsphere

Following this question, I want to create a sphere from a tetrahedron using this Wolfram support. But so far the resulted sphere is bigger than it should be and center seems to have an offset. ...