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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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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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 ...
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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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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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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. ...
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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 <...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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....
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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:
...
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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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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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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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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 ...
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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. ...
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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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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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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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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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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 ...
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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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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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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 ...
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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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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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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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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 ...
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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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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,...
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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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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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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 ...
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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 ...
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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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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 ...
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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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How do I adjust the start diameter of a spotlight in Unity?
To clarify, I'm an experienced 3D modeller, but there are hiccups here and there getting used to Unity's interface.
I'm working with an adjustable spotlight for a game; it can be mounted and directed ...
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how to efficiently raytrace a rectangle side in 8bits without mul and div?
Imagine you are on a hardware that is 8bits like the nes or the game boy,
NO mul no div, only add and shift.
Given a rectangle or integer size nk*mk,
where k is the size of the underlying grid, and P ...
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How do I get the consistent time it would take for two points to reach each other in circular motion?
I'm making a 2D game. It involves the player swinging around a grapple hook in perfect circular motion, however, I want to make the cooldown for this ability based on predicted end position for the ...
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Optimal way to find the closest entity to player with a restricted set of functions
The scripting engine of Skyrim (and Fallout 4) has an interesting function called FindClosestActor(x,y,z,radius). If you call it with x,y,z center coordinates and a radius, it returns the closest ...
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Extracting cell center and corner points from rasterized Voronoi diagram
I currently have this code which I copied from Rosetta code:
...
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Deriving shadow position from a 2D heightmap
I have a 2D heightmap with discrete values. Based on these values they should cast a fixed position shadow (constant angle respective to the "sun"). I can figure out how to cast it on a flat ...
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How to project 3D meshes onto a 2D plane producing a 2D polygon silhouette?
I would like to project a number of separate 3D meshes onto a 2D plane and create a 2D polygon representing the outline of all the meshes. I would also like to to create multiple 2D polygons if the ...
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Arranging points in a 2D grid so that successively added points approximate a square shape
So, I ran into a problem with placing points in a grid while always trying to fit them into a square. Here are some examples (the numbers represent the order of placement):
Placing 1 point:
...
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How to find the center of mass from CapsuleCast in unity
Is there an easy way to find the center of mass from a CapsuleCast, or should I find the geometric center of it?
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