# Tagged Questions

A 2D shape consisting of straight lines that are joined to for a circuit.

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### How can I add and subtract convex polygons?

I have two 2D convex polygons overlapping each other. I am looking for an algorithm to subtract and add them. The result must be a single concave polygon or (even better) a set of biggest convex ones ...
996 views

### How to calculate a bounding rectangle of a polygon?

Polygon poly = new Polygon(); poly.getPoints().setAll(5d, 15d, 15d, 25d, 5d, 30d); How do I calculate the Polygon's height and width? There is no poly.getWidth() or poly.getHeight() method in javafx....
221 views

### What do the 6 points stand for in Polygon().getPoints().setAll?

I have the following code to create a polygon: Polygon poly = new Polygon(); poly.getPoints().setAll(14d, 17d, 26d, 17d, 20d, 27d); // What do these mean? What do these 6 points stand for?
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### Separating axis theorem with multiple polygons?

I am attempting to implement the separating axis theorem in C#. I have a function that can calculate the minimum translation vector between two polygons. However, I can't seem to create a function ...
196 views

### Moai: Clipping an image to a polygon

I'm using Moai SDK. I have an image and some random convex 2D polygons. I want to show only the parts of the image inside these polygons. Here's an example image: The same, shown only where the ...
8k views

### Mesh with quads to triangle mesh

I want to use Blender for making models yet realize some of the polygons are not triangles but contain quads or more (example: cylinder top and bottom). I could export the the mesh as a basic mesh ...
199 views

### What decrease of polycount should occur as a function of distance?

What decrease in polycount should occur as a function of distance. I make a terrain and I wounder what is the right formula to keep the "poly size"(the screen size) constant. Or is there some mental ...
2k views

### Polygon count budget

Is there any smart way to think about polygon budget relating to PC gaming today? My game will have one static 3d background scene and two fighters. No more enemies. I am thinking about having ...
2k views

### Would it be more efficient to handle 2D collision detection with polygons, rather than both squares/polygons?

I'm working on a 2D game engine and I'm trying to get collision detection as efficient as possible. One thing I've noted is that I have a Rectangle Collision collider, a Shape (polygon) collider and a ...
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### How can I get textures on edge of walls like in Super Metroid and Aquaria?

Games like Super Metroid and Aquaria present the terrain with the other facing parts having rocks and stuff while deeper behind them (i.e. underground) there's different detail or just black. I ...
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### Get polygons points from an array of 0 and 1

I have an 2D array containing 1 for walls or 0 for empty cells. I can draw my maze by iterating through the map, placing a wall when map[x][y] is equal to 1 but I want to get the points of the ...
625 views

### How do I get the areas enclosed by an arbitrary 2D shape?

In my game I want users to be able to draw arbitrary 2D shapes of any length around game objects. The shapes must be closed and drawn with a single stroke that does not overlap. For example: I ...
1k views

### What caused “falling out of the world” and what fixed it?

A lot of early 3D games had the problem where you'd be trundling merrily along and suddenly everything was black, with an island of what looked like the hollow facade shell of the scene you'd been ...
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### Farseer Physics: How to create shape from Vertices?

As you can understand from the title, I'm pretty new to game development. I'm doing this for fun. Anyway here's my question. I have this Farseer Physics samples and i've been studying them for a few ...
297 views

### Random 2D point in rectangle, but not in a polygon

I have a static rectangle and dynamic polygon. I need to generate a random 2D point in that rectangle, but not in a polygon. This is what I mean: Green is where random point can be generated and ...
151 views

### How to render polygons of arbitrary shape? [duplicate]

I am trying to render a plane with nodes. FYI : Nodes know what other nodes it is being attached to. I can think of a way to render them as long as they are aligned in a circular pattern; have a ...
280 views

### Generate inner polygon from a parent polygon

I want to produce a polygon inside an arbitary polygon. The inner polygon shall be distanced from the outer polygon with a fixed distance, d. I will use the inner polygon as a border for player ...
219 views

### games logic based on closed shapes

I would like to know the math concepts behind shape based games like http://www.miniclip.com/games/fat-slice/en/ To be specific, I would like to know on how to model shapes programmatically finding ...
2k views

### Can SpriteBatch be used to fill a polygon with a texture?

I basically need to fill a texture into a polygon using the SpriteBatch. I've done some research but couldn't find anything useful except polygon triangulation method, which works well only with ...
2k views

### Create Box2D and engine polygon Box2D body without sprite

Hey I have created my body using following code: (please read full description) Body polyBody; final BodyDef mBodyDef = new BodyDef(); mBodyDef.type = BodyDef.BodyType.DynamicBody; ...
823 views

### ray polygon intersection

Hi, I am looking for an elegant way to do ray and polygon intersections in 2d. I don't care about languages. Now what I'm doing is taking a line that lies on the ray (with a screen length) and ...
549 views

### How to make a stack stable? Need help for an explicit resting contact scheme (2-dimensional)

Previously, I struggle with the sequential impulse-based method I developed. Thanks to jedediah referring me to this paper, I managed to rebuild the codes and implement the simultaneous impulse based ...
377 views

### Greiner-Hormann clipping problem

I have a set of planar polygons in 3D space defined by their vertices in counterclockwise order. Let's define the 'positive face' as being the face of the 3D polygon such as when observed, the ...
1k views

### I need help with 2D collision response (of stacking rotating polygons, with friction and gravity, for a game)

Hi I am looking for suggestions on how to write a collision response for game programming purpose (so not a scientific simulation). I am dealing with 2D polygons that are rotating, and I want them to ...
345 views

### Is there any heuristic to polygonize a closed 2D raster shape with n triangles?

Let's say we have a 2D image black on white that shows a closed geometric shape. Is there any (not naive brute force) algorithm that approximates that shape as closely as possible with n triangles? ...
185 views

### Splitting Graph into distinct polygons in O(E) complexity

If you have seen my last question: trapped inside a Graph : Find paths along edges that do not cross any edges How do you split an entire graph into distinct shapes 'trapped' inside the graph(like ...
916 views

### Scan-Line Z-Buffering Dilemma

I have a set of vertices in 3D space, and for each I retain the following information: Its 3D coordinates (x, y, z). A list of pointers to some of the other vertices with which it's connected by ...
238 views

### Scanline filling of polygons that share edges and vertices

In this picture (a perspective projection of an icosahedron), the scanline (red) intersects that vertex at the top. In an icosahedron each edge belongs to two triangles. From edge a, only one triangle ...
4k views

### How can I make Maya export a mesh as double-sided?

I'm exporting from Maya 2009 to OBJ. The mesh I'm exporting has in it's Render Stats "Double Sided" checked, but when the polygon is exported, only a single side is actually exported. What really ...
244 views

### Algorithm for approximating sihlouette image as polygon [duplicate]

Possible Duplicate: Is there any heuristic to polygonize a closed 2D raster shape with n triangles? I want to be able to analyze a texture in real time and approximate a polygon to represent a ...
485 views

### Polygonal Triangulation - algorithm with O(n log n) complexity

I wish to triangulate a polygon I only have the outline of (p0, p1, p2 ... pn) like described in this question: polygon triangulation algorithm and this webpage: http://cgm.cs.mcgill.ca/~godfried/...
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### Polygon count target range for MMO being released in 2 years

What would a realistic poly count target range be for NPC and player models in a 3D MMO that will be released in 2 years? What about poly count target range for the entire camera view (environment, ...
703 views

### 2D SAT Collision Detection not working when using certain polygons (With example)

My SAT algorithm falsely reports that collision is occurring when using certain polygons. I believe this happens when using a polygon that does not contain a right angle. Here is a simple diagram of ...
519 views

### Collision within a poly

For an html5 engine I'm making, for speed I'm using a path poly. I'm having trouble trying to find ways to get collision with the walls of the poly. To make it simple I just have a vector for the ...
260 views

### How can I locate empty space next to polygon regions?

Let's say I have the following area in a top-down map: The circle is the player, the black square is an obstacle, and the grey polygons with red borders are walk-able areas that will be used as a ...
242 views

### How can I move a polygon edge 1 unit away from the center?

Let's say I have a polygon class that is represented by a list of vector classes as vertices, like so: var Vector = function(x, y) { this.x = x; this.y = y; }, Polygon = function(vectors) { ...
627 views

### Adding tolerance to a point in polygon test

I've been using this method which was taken from Game Coding Complete to detect whether a point is inside of a polygon. It works in almost every case, but is failing on a few edge cases, and I can't ...
506 views

### How to decompose a rectangular shape in a Voronoi diagram, only generating convex shapes?

I think this is a very straighforward question, lets say i have a building in 2D, a rectangle shape. Now i want to decompose that area in a lot of convex shapes, as seen in a voronoi diagram, or ...
817 views

### Puzzle game: clipping of non-convex polygons on the figures

I have an original figure in the SVG file. I need to break it randomly on parts, an example of which is specified below: I have an idea, to use for partitioning Voronoi diagram (Fortune's algorithm). ...
857 views

### Algorithm for constructing the corners of a regular, n-sided polygon

I've googled this using a lot of keyword combinations, but to my great surprise I could not find an algorithm for constructing a regular, n-sided polygon into a given circle, i.e., finding the ...
616 views

### Do I need to roll my own polygon segmentation algorithm to automate Box2d body creation from a tile map?

Before re-inventing the wheel I figured I'd ask: I'm working on a tile-based 2d-maze level generator for cocos2d + box2d. The idea is: I'm using one of the well-known graph traversal algorithms to ...
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### A* navigational mesh path finding

So I've been making this top down 2D java game in this framework called Greenfoot and I've been working on the AI for the guys you are gonna fight. I want them to be able to move around the world ...
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### Box2D + Love2D (Lua) - Assertion fail with polygon meshes

When I try to create a triangle collider for my game it sometimes leads to an assertion fail. I use the physics engine that comes with love2d (Box2D). That's the error message that appears when the ...
822 views

### Maya 2012: Is it possible to convert a single polygon to solid object?

Is it possible to somehow extrude a single polygon into creating a solid object (ex: converting square polygon to cube)?
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### How did they do it: Trine 2.5d terrain?

How did they make the terrain in trine? I think they took a polygon approach. It doesn't seem that they used a heightmap because it is in all three vectors, or a voxel method because it doesn't have ...
4k views

### How do I handle collision detection so fast objects are not allowed to pass through walls?

I'm creating a 2d sidescrolling shooter, and I'm having a little trouble with collision detection for the bullets. Everything including the bullets are objects with their own polygons / update methods....
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### How do I align the matrix used in SpriteBatch and the matrix used in BasicEffect?

I'm writing a Windows tool that uses XNA and allows the user to place textures on the screen. I'm using a 'camera' for the SpriteBatch used to draw the textures, e.g: Matrix matrixForSpriteBatch = ...
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### Polygon editor to draw collision data over image

I need an editor to plot a polygon over the texture for of a ship in my game. It would look like this.. Where the red is the collision outline and the image is the texture. I want to store the ...