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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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 can I make the inside of a mesh solid?

I followed this tutorial to create a simple liquid effect. I am trying to modify it to make an effect where it looks like the liquid is covering an object. I have a shader that changes the alpha of an ...
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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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Convert between WCS and OCS using quaternions

I have been scratching my head for days understanding how to fully describe an object fully using just the normal vector and an insertion coordinate. Specifically this is for creating DXF files, but ...
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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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Program doesn't detect a ray triangle intersection correctly

Every frame I check if a ray intersects a triangle. But in practice program tell me that triangle is intersected only when I move camera on to it's position. I don't even have to put cursor on a ...
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Needs help on actually making the trigonometric function work as intended

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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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Approximate doom/heretic-style freelook distortion with modern graphics APIs

Currently working on a doom-like engine with fewer technical limitations, and looking into rendering techniques. I'm aware doom's a raycaster, and I want to capture a similar look but with modern ...
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How do I find the correct vectors perpendicular to a vector in between two vertices?

I'm trying to push the purple vertices inward by moving it with a vector perpendicular to the red vector shown in the picture. Each directional vector created will move its respective vertex towards ...
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1 answer
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How can I remove unnecessary vertices from wall edges?

I've got a pretty simple tile based 2d top-down map with an array of walls. In order to figure where to cast light and shadows, I've generated an array of vertex coordinates along the walls like so: ...
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How can I draw a partial circle with LineRenderer?

I'm using the following code, which I found online, to draw a circle with a predefined radius centred on a predefined point in LineRenderer (2D game). ...
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Rotating two types of cubes -- one cube's sides disappear

I had a cube that had 8 vertices and 12 triangles and the visibility of the cube was okay. When I rotated, I was able to see all visible sides of it. Here is my old cube: ...
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Writing a sphere-sphere intersection function

I am writing a function where I have two 3d points with coordinates {x, y, z} both with a line segment of a given length. I am trying to find a common endpoint between the two line segments closest to ...
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Dual Contouring - Eliminating sharp edges

I want to remove the sharp edges (Cubic looks) of Dual contouring. It currently looks like this: This is what I get when I try to implement QEF: ...
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Movement within a circle, but the circle bends around obstacles?

I wish I knew a better way to phrase this, but I want to make an object move from point to point inside a circle. But I also want that "circle" to bend around obstacles, so that no matter ...
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2 answers
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Placing a circle as close as possible to a specific coordinate without overlapping another circle

I am working on a 2D game in Java. My goal is to place a ball as close as possible to the center without overlapping the balls that are already there. How can this be done?
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2 votes
1 answer
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Formula for attack range using hexagons

I need a little help with a formula to calculate the attack range for my turn-based strat game. Since it's a hexagon grid, I'm having trouble coming up with a formula that would pick the character ...
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How to check if a point is on the plane given bottom-right point, top-left point, normal and the quaternion rotation of the plane

I know the world positions of A and B. We are also given the vector normal and the quaternion rotation of the plane How do I check if a point lies on the plane?
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Getting the point of intersection from this fast ray box intersection algorithm

I have seen lots of such algorithms that return a Boolean value, but I also need to get back the intersection point and ray length. I am looking into this example, but I'm not sure how I can extract ...
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Clipping walls in Doom-style FPS view

I have two points representing a line, and a player position. I translated and rotated the points around the player, and this works just fine. Next I want to clip the resulting line like Bisqwit did ...
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What is the relationship between gimbals and Euler angles?

Through reading a lot of articles, I understand what gimbals are (at least I think so). And I know that Euler angles follow the rules of gimbals, but why? Why do Euler angles comply with the rules of ...
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How to handle movements of objects in a platformer with a cylindrical map?

I was wondering what would be the best approach for a game with a perspective like Resogun, where the world wraps around in a cylinder: In my opinion, the easiest approach is to: have a "...
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How can I implement an aiming system like the Tank Stars mobile game?

I have been trying to implement the same aiming system as in Tank Stars, but I got a little stuck. I implemented simple stick aiming, which basically aims towards the stick movement. In Tank Stars, ...
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1 answer
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Seam on UV Sphere [duplicate]

I created a uv sphere model in Blender, and I'm loading it as an obj into my OpenGL game. I'm attempting to model a 2d image as a texture for this sphere to make the moon, but I've run into this issue....
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Check if a triangle is back-facing in a 3d model

I'm creating 3d models with an algorithm, but i have no idea how to make all triangles in the mesh face the right direction, so some faces are facing inside the model. The list of vertices is sorted ...
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How can I reduce a frustum to the subset that passes through a portal AABB?

I'm trying to implement portal based occlusion culling: There are sectors and portals. When a portal is visible, the sector it is connected to is rendered. The sector is made of polygons and ...
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How much is 2D geometry used in 3D? [closed]

I'm studying 2D geometry with eventual goal to study 3D geometry for building games - very much looking forward to 3D!! Looking up on how to calculate hypotenuse of a right triangle in 3D I read that ...
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Can you help me resolve a bug in mesh collision code?

I have entities which walk along a 3D mesh. I move the units along their x,z axis, and every frame I update their y-position according to the quad or triangle they are standing on, using Barycentric ...
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finding the angle of rotation of a 3d line

I have a line segment joining two 3D points AB, and a vector V which is normal to it. I need to know the angle of AB in the plane described with V as the plane normal, that is: in the plane of the two ...
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Closest circle intersection within a triangle

(Context: I use a Delaunay triangulation for pathfinding, and have circular points of interest, of varying sizes, being randomly placed around the map. Units need to be able to determine the closest ...
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Generate vertices of a sphere by using spherical coordinates

I'm trying to generate points for a sphere by subdividing the space of spherical coordinate in res sector and res slices. At first I did my own implementation, but it wasn't working. After a while I ...
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Find projecting triangle for UV mapping in RuneScape model format

I am using an old Runescape model format, also used by Thief and Quake. In this format, instead of specifying UV coordinates for each vertex ABC, we specify a second trio of vertices PMN. Those ...
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What is the math to project a 3D object's center onto a 2D plane?

What I really need is the x,y of the object when it is outside of the screen: I'm actually coding a UI in Objective-C, not a game. In this different kind of UI you navigate a 3D space with objects. ...
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Creating Sphere Triangles from Vertices

I came across a way to create the vertices of a sphere, located here: https://gamedev.stackexchange.com/a/150293/62793 I converted this to the following C# example: ...
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Make Minecraft Main Menu Camera movement

I intend to make exactly like this. I highly suggest you watch just 5 seconds of the video because it already explains what I intend to do. I've been trying cosine and sine on vector3s but I can't ...
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