# Questions tagged [splines]

A spline is a sufficiently smooth polynomial function that is piecewise-defined, and possesses a high degree of smoothness at the places where the polynomial pieces connect.

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### Unreal Engine: How to detect is player inside closed loop spline or out?

I have a region limited by closed loop spline. How to detect is player's position inside that region or not?
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### custom 2D skeletal animation

I'd like to animate my 2D player by interpolating him between keyframes of joints/bones. He's to be very simple, just a chunky stickman outline of coordinates with no sprites. I want to make it all ...
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### List<Vector3> of line segments (start, end position) from jointed CapsuleCollider chain

What I'm trying to do I'm trying to create a list of positions which I can use to define a centripetal catmull–rom spline; however I can't think of a solution for creating the list of positions which ...
102 views

### Performant way to generate a cylindrical mesh along a dynamic spline

I am working on a mobile game, in which I am tiling a cylindrical mesh along a dynamic spline. The points of the spline are changing each frame, so the vertex positions and normals of the tiled mesh ...
• 4,856
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### Rear Propulsion Steering Spline, or what is this called?

What I am looking for is essentially to know what this is, or what I can google to learn how to do it... unless of course the solution is simple. You have an object at the start position facing a ...
• 101
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### Why do computer graphics applications use piecewise polynomial curves of degree 3 rather than curves of higher-order, say degree 100?

just wondering why is that? can't get my head around it. wouldn't the use of degree 100 be better? I'm really new to this stuff.
166 views

### How to create a 2d procedural spline based road with 2 edge colliders?

I am trying to make a top down 2d spline-based road that is procedurally generated and endless. The aim is that the player starts inside the road and has to navigate the road and if he touches any of ...
• 101
1 vote
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### What are spline input keys?

There isn't a really adequate explanation of these anywhere on the internet, so I thought I'd ask this question here. What are spline input keys in Unreal? How are they represented in Unreal? Also: ...
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### Higher order splines for use with pathfinding

In this page, Amit explains that splines can be used to achieve movement on a found path. In the picture below, he explains that: The blue paths use splines, with dark blue being low order ...
1 vote
761 views

### How to draw a diagonal sine wave line renderer

I'm trying to use a LineRenderer component to draw a sine wave from point A to B and I'm using mouse position. However what I did so far is not working as expected, ...
1 vote
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### How can I make a spline that does not overshoot?

I have a list of line segments that run through a track model and I am looking to achieve two things: smooth the overall shape of the path being able to evaluate a position by querying from ...
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1 vote
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### High-level advice on procedural river (Unity3D) [closed]

I'm working on some procedural content for Unity3D - in C# My main aim is to build a flat plane (or maybe later a terrain / mesh), with a single river running through it, based on a seed value. I ...
• 123
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### The difference between shading and data interpolation

Using methods like Phong you can make mesh look smooth and real. However you can do the same interpolation at the data level creating a surface (for example B-Spline surface). What is the difference ...
3k views

### Parametric form of a cubic function

After researching about curves in computer graphics (splines in my case), I have come across something I did not know: Explicit functions like: $y=x^2+2$ are not the best way to interpolate between ...
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### Why aren't regular quadratic and cubic splines used much in games?

After investigating a bit about splines and reading a bunch of docs, I have noticed regular quadratic and cubic splines are not used very much in games. Splines using quadratic/cubic Bézier curves, ...
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### How do splines work?

I've been beginning to work with different kinds of splines (e.g. Bezier, Hermite, B-splines) in some of my work with computer graphics and I am trying to get a grasp of how they work (mathematically ...
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### Spline type to achieve a specific result

Is there a type of spline which can produce (approximately) the following result given the specified points indicated. I want to be able to specify how curved the corners are from the "centre points" ...
1 vote
491 views

### What is next to interpolate camera position with smooth speed changes?

I am working on a path camera to be used in demo playback. (3d game) The spline math used is catmull rom. I am on my second attempt to get constant position speed :( (someone else is doing rotation). ...
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### Determine if AI can traverse a given spline

I have some AI Agents that I want to navigate along a spline. The agents have a speed and a maximum turning radius. For some splines the curvature is too tight for the AI agents to navigate around and ...
• 505
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### How can I constrain motion to a path formed from multiple splines?

I want to develop a system to constraint a character movement to a certain path, defined a-priori by the level designer to give some sort of 2D/2.5D look. Right now I have a list of splines that make ...
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1 vote
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### Constraining Movement to Path/Splines

First of all take a quick look at this : https://www.youtube.com/watch?v=LQtKP-EymFM So this is to give a idea of what I mean by following a path, basicly I am trying to understand how something ...
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### How can I find the tangent and normal at an interpolated point on a Catmull-Rom/Hermite spline?

I have an implementation of a simple Catmull-Rom spline. It works, but I'm trying my hardest to be able to place vertices at extrusions along the curve. For this I need the normal (and tangent in the ...
• 1,235
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### How to follow object on CatmullRomSplines at constant speed (e.g. train and train carriage)?

I have a CatmullRomSpline, and using the very good example at https://github.com/libgdx/libgdx/wiki/Path-interface-%26-Splines I have my object moving at an even pace over the spline. Using a simple ...
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### How can I make a spline out of three points that define a circular arc?

I was looking at the descriptions of various curve techniques here and noticed the mention of circular arcs. I want to implement something like this, but I'm not quite sure what the correct formula to ...
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### How can I create or extrude a mesh along a spline?

Let's say, for example, that I have a working spline. I want to use this spline to create a mesh, but I'm not quite sure how to go about it. For example, I want to create a road along this spline. I ...
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1 vote
285 views

### Compute world position by walking N units along spline?

My goal is to move ahead along a spline 'x' world units, unfortunately there is no way to map spline points to world points. What I do is I iterate along the spline by a small alpha amount (say 0.001)...
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### How do I avoid interpolation artefacts when scaling up a heightmap?

I am using a bicubic interpolation algorithm in order to upscale a height map, and I am noticing some artifacts around the pixels boundaries. However, these artifacts don't seem to appear when I use a ...
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### Animating values using splines

I'm trying to create a system similar to Blender's f-curves or Unity's animation curves (google it, I'm not allowed to post more than two links yet). It's basically a 2D spline where time is on the X-...
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### How to unify vertices in 3ds max?

I want two vertices of editable spline become one. Neither fuse, nor weld helps: vertices remain separate. Here is a video: ...
• 221
1 vote
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### Is there a game not using meshes for models? [closed]

Traditionally, models consist of lots of vertices connected by triangles. That forces the use of a high amount of vertices for detailed organic shapes or makes models kind of blocky. Even though ...
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### How to remove bezier handle in 3dsmax?

While editing spline, I need to make one of the vertexes to be an absolute corner. I.e. bezier control points should be in zero distance from the vertex. How to do that?
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### Tessellating to a curve?

I'm creating a game engine, and I'm trying to define a 3D model format I want to use. I haven't come across a format that quite does what I want. My game engine assumes a shader model 5+ environment. ...
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1 vote
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### Find the nearest control points either side of a Catmull Rom spline segment

There is a formula for evaluating a Catmull Rom spline segment at time 't' found here. The problem with this is that it requires finding the two control points either side of the segment to evaluate. ...
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1 vote
3k views

### Interpolation between two 3D points?

I'm working with some splines which define a path a character follows (you can see a gameplay video here to get a better understanding of what's going on: http://www.youtube.com/watch?v=BndobjOiZ6g). ...
• 1,480
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### How would one determine the length of a path?

I have a game that requires each player to move along one specified path. I draw the path using Bézier curves. How can I determine the total real (not linear) length of the path and the distance that ...
• 661
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### Determine arc-length of a Catmull-Rom spline to move at a constant speed

I have a path that is defined by a concatenation of Catmull-Rom splines. I use the static method Vector2.CatmullRom in XNA that allows for interpolation between points with a value going from 0 to 1. ...
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