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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.

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1 vote
1 answer
114 views

### How to calculate the surface area of a irregular 2D polygon in Godot?

I have a irregular 2D polygon, it is a PackedVector2Array, how do I get its area?
1 vote
1 answer
93 views

### How to rotate a 3d grid?

I have a spatial hashing grid that's mapped out like ...
• 13
0 votes
1 answer
77 views

### IIn video games, are slight damage details, like say on a tank, made by modifying the geometry or by using textures?

Here are images of real tanks and I drew arrows into the places with slight damage: In video games, are those made by modifying the geometry or with textures?
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0 votes
0 answers
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### How do I move a point in a specific direction in 3D Space?

I know how to move a point in a direction in 2D space it's like this: pointX += sin(angle) * movementSpeed; pointY += cos(angle) * movementSpeed; How do I do the ...
1 vote
2 answers
80 views

### Representing a concave polygon as a hull "minus" convex cavities

I am implementing 2D collision detection, and trying to tackle the problem of concave polygon vs. shape. The SAT works only for convex shapes. I was wondering if the following approach is a viable ...
2 votes
0 answers
48 views

### Rebasing barycentric coordinates to an adjacent triangle

Say that in a 2D space I have the barycentric coordinates B=(Bx, By, Bz) of point P relative to triangle T. I now need to calculate the barycentric coordinates B' of P relative to triangle T', where T ...
0 votes
1 answer
111 views

### How can I calculate vertex positions for a rectangle outline using a unit square, vertex normals, model matrix and outline thickness?

I'm trying to draw a hollow rectangle (i.e. the border of a rectangle without the middle) using a unit square plus normals. The actual positions are being calculated in my vertex shader. For example, ...
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2 votes
1 answer
174 views

### Approach to rendering a planet texture

I'm making a space game using Godot 4, and I need to capture the "hugeness" of planets. I figured I'd use spheres with textures on them for planets. The textures have identifiable ...
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0 votes
1 answer
46 views

### Checking if I am looking through a window using angles

I am developing a mod for a game with a Lua api. I am trying to detect if I am looking through from behind a window when I shoot an enemy. For context, when I shoot through this window I apply a ...
1 vote
2 answers
186 views

### Calculate path segments size

I have a problem more closely described on a picture below. The idea is that I have my agent in point A and I want to get to the point B. The problem is, that agents rotation towards point B is alpha ...
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21 votes
2 answers
8k views

### What is a "normal" in game development

I'm new in Game development and probably this is a silly question. I had a look online but haven't found a clear answer, I did it bit quick but enough to evaluate that this is a confusing topic ...
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0 votes
1 answer
110 views

### How can I correctly pass 2 vertices instead of all 4 for a quad to a vertex shader?

If I am rendering quads, but all the quads will be axis-aligned (that is, their plane is always parallel to either the X Y or Z plane), I thought I could cut vertex video memory usage in half by ...
• 143
10 votes
3 answers
9k views

### How do game engines avoid recalculating normals upon mesh rotation?

Assume that a face of a mesh is defined by vertices A, B, C and that the normal of the face ...
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2 votes
0 answers
72 views

### Aligning vector by rotation around non-orthogonal axis

This is almost more a geometry/mathematics question than a game dev one, but I think I'll have a better chance actually understanding the answer if I ask here. Rather than try to explain it- because ...
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3 votes
0 answers
217 views

### How to test for intersection of a cone with infinite camera frustum (no near/far plane)?

I have a given infinite camera frustum defined by four planes, each defined by a normal (left, right, bottom, top). From those planes we can also easily get the camera position and the view direction. ...
1 vote
1 answer
118 views

### Vertex Shader Sphere Projection and CPU Distance Calculation

I have multiple planes whose vertices are transformed to a position on a sphere in the vertex shader. The GLSL function called pointToSphere transforms a point <...
0 votes
1 answer
84 views

### How to calculate angular momentum of two colliding bodies about their shared center of mass in 2D?

I'm following this guide to implementing collisions in 2D physics. It shows this diagram, but I don't understand how to calculate the values of Da and ...
0 votes
0 answers
187 views

### Generating tris for concave polygon 2D

I have an arbitrary array of points that describe vertices of the polygon 2D, they ar in order. To generate plane mesh for that, I need to generate tris. For something like circle/hexagon/square it is ...
1 vote
0 answers
26 views

### Move a non-convex polygon's outline inwards?

The polygons are small 3D parts of a quasi sphere centered in the origin and a solution that works in the plane can easily be made to work in this world. I tried to move the outline inwards by using ...
2 votes
2 answers
192 views

### Finding the closest point on a circle to end of a ray in 3D

I have a circle in 3D space, so we have center C with radius r, and the normal of plane the circle lies on, N. There is also a normalized vector V that I am modifying to go far past the circle's ...
3 votes
2 answers
217 views

### How to check if player actually went through a trigger area and didn't just touch it?

I'm trying to make a racing game that measures your distance from the center-line of the road. To do this I need to check on which part of the road the player is, so the calculation is correct. (If it ...
0 votes
1 answer
80 views

### Discontinuous Normals on a Normalized Cube Mesh with Displacement Texture

In my project, I have created a normalized cube using six plane meshes. To improve its visual quality, I added a displacement texture and calculated the normals for that texture to ensure proper ...
0 votes
1 answer
63 views

### Rotating around 3D cube Camera Controller for Unity

I am Unity game developer with more than 2 years experience. I am working in a personal project, a mobile game for Android in Unity. I am trying to make a camera controller for a 3D Cube Game in Unity....
0 votes
1 answer
38 views

### How to correctly position a set of cuboids based on a direction property in MonoGame

I am trying to create a map for my game using a list of cuboid sections that are defined like this: ...
0 votes
0 answers
27 views

### Two moving and rotating bodies, how to approximate hitbox of a trajectory of a point on one body in the coordinate system of other

The game is in 2D. Let's say I have two bodies: A and B, each with position, angle, velocity vector, and angular velocity (I'm not sure yet if I should be using angles, or rotation matrices). Given a ...
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0 votes
2 answers
467 views

### How to get area of 2D shape bounded by vertical and horizontal line segments?

I am making a game similar to Volfied using Unity: The player outlines an area using straight lines, either horizontal or vertical. I am stuck at the algorithm to decompose the area into rectangles ...
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0 votes
2 answers
233 views

### How do I detect collisions with a circle sector against basic geometry?

For the 2D game that I'm building, I want some entities to be able to use areas of attack, such as a wedge/circle sector area of attack. In this case, the circle sector is a pie-slice shaped section ...
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0 votes
1 answer
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### What is the point of Geometry2D.make_atlas()?

I'm completely bewildered by the Geometry2D.make_atlas() method. I believe it has to do with texture atlases based on its name and comment on its source code but am ...
0 votes
1 answer
473 views

### Two methods of finding angle between vectors give different answers!

Ok, am I misunderstanding how Unity quaternions work, or is there a bad (about 2 degrees difference!) floating point error? The TLDR is I use a quaternion r to rotate vector v and put the result in w. ...
0 votes
1 answer
309 views

### How to create an octahedron for sphere subdivision?

I have vertices that generate the first out of two pyramids. However, I want to have the second pyramid facing downwards as to make an octahedron. What are the correct vertices to use, because I've ...
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0 votes
1 answer
138 views

### Help understanding the math to position sphere vertices by latitude and longitude

For a project of mine, I need to render spheres without loading a pre-made model or using built-in functions. I found this bit of code on the internet that seems to work but I really want to ...
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0 votes
1 answer
76 views

### Align two meshes given 2 faces

I have two meshes (A and B) and I know that a triangle in A has the same size and same angles as a triangle in B. For simplicity, suppose A is an octahedron and B is a tetrahedron. And suppose the ...
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0 votes
1 answer
195 views

### GameObject mesh.vertices array is empty

I've an Icosphere GameObject: I want to iterate over each of the faces and change the material based on their distance from the center, however I don't seem to be able to retrieve the list of ...
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0 answers
50 views

### Wheel position on surface

I have a bicycle with suspension and need to find the contact point of the wheel on the "road". If the front fork was pointing straight down, it would be as easy as doing a raycast down the ...
1 vote
1 answer
167 views

### Given a quad in 3D space with two diagonally opposite points and normal, how would I find the other two points?

Image attached below for clarification: So here we have a plane with a random rotation in 3D space, and we have the values for P1, P2, and the plane normal. How do I find the points X1 and X2? This ...
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1 vote
1 answer
64 views

### Add and Removing Elements on the Circumference of a Circle

I am trying to spawn entities on the circumference of a circle. These entities may be removed at any time, including all of them being removed. Periodically I would like to add an element on the ...
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0 votes
1 answer
83 views

### Finding point along vector to maintain distance to an arbitrary point

I'm currently working on a particular project where orthographic and perspective projections are both used interchangeably. To keep the transition between both projection modes somewhat seamless, I ...
0 votes
1 answer
150 views

### How to spread circles evenly around a point?

In my game there's a part where a bunch of circles need to evenly spread around a point. Like in this demo below: ...
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2 votes
0 answers
61 views

### Audio emission from a polygon instead of a point

I'm developing a 2D game in Godot. The engine doesn't matter in this case. Given a polygon, convex or concave, and a listener (camera) location, what 2D position should an audio emitter be placed at ...
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2 votes
1 answer
586 views

### Efficiently find all points within a circle

I am writing code that requires me to find all points within circle on certain parts of the screen hundreds of times per frame. I wrote a quadtree for this and have 1 method called query_circle that ...
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0 votes
0 answers
218 views

### How can I move an object on a non flat surface in vulkan?

I am writing a small "game" in vulkan, in which a car can move in an environment that is not flat, like a desert with valleys. I am able to translate my car and follow it with the camera on ...
0 votes
1 answer
93 views

### Tangent Space View Direction based factor value remap

I'm trying to setup a mask similar to what Fresnel produces. Unfortunately Fresnel gives pretty bad results at grazing angles so I ended up using this : ...
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2 votes
2 answers
389 views

### Finding the position of a point based on a relative point inside a quad

I'm trying to get the relative point position on a quad using a [0,1] Vector2, like in the picture below: The red dots are relative positions. What I'm trying to make is a function that takes the A,B,...
1 vote
1 answer
681 views

### Find closest open space in grid of rectangles?

I'm making a builder game where you snap arbitrarily sized rectangles into a 2D grid. I want the player to be able to drag and drop these rectangles anywhere on the grid, but prevent collisions (i.e., ...
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3 votes
0 answers
1k views

### Wall sliding collision resolution with multiple objects

TLDR My collision resolution algorithm with wall sliding works perfect for multiple walls but it fails when the angle of the corner of two walls is less than 90 degrees. (acute angles) and the player ...
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0 votes
1 answer
203 views

### Find out (general) orientation of cube faces with rotated and translated camera

I have the following problem. I have a camera that is initially looking at a cube. The cube is with center at (0, 0, 0). The camera that is initially on (0, 0, 60). The camera can rotate and translate ...
0 votes
0 answers
78 views

### Finger (Sensor) Shaking Detection

I want to make the user be able to shake a certain object through the phone's sensor. I have drag&drop mechanics now, and I want this shake to be directly related to that mechanics. How would that ...
0 votes
2 answers
75 views

### Changing Model's rotation to keep its left side toward the pivot as it goes in a circle

I wrote a little script for my scene that allows my ship to circle an island, and it seems to work alright. Now I am trying to get the ship model to stay broadside to a pivot point in the center of ...
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2 votes
0 answers
17 views

### Create a quad that faces a given normal [duplicate]

Let's imagine that we have a given normal, (it could be done with source and destination points but let's say that source is 0 0 0 and the destination has been already normalized) What could be the ...
0 votes
1 answer
114 views

### writing a custom Quaternion.FromTo

I'm using the new Unity.Mathematics library. I'm trying to to replace Quaternion.FromTo(Vector3 from, Vector3 to) which returns a quaternion with what it would take ...
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