# Tagged Questions

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

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### Box2d polygon skin

In manual is see: Polygons inherit a radius from b2Shape. The radius creates a skin around the polygon. The skin is used in stacking scenarios to keep polygons slightly separated. This allows ...
127 views

### How to calculate ray polygon intersection? [duplicate]

I'm in a class where we are creating a ray tracer from the ground up in C++. I'm at a point where I can't seem to wrap my head around the math that is required to calculate the point at which a ray ...
62 views

### How to create polygons from tilemap areas?

I'm currently working on a project which needs simple AI's to walk around using pathfinding. I'm trying to find a way to generate a polygon based on the connected tiles (explained below), an i'm ...
30 views

### Locate point of collision for two moving lines

I am trying to implement a continuous collision detection system that checks collision between two polygons for a certain time step, concave or convex. It makes the simplification that the path ...
63 views

### Cubic bezier polygon clipping

I have a large cubic bezier defined 2D polygon area which I need to render in DX11 real-time to create as many 4096x4096 textures as needed. An average control point count would be around the 12k and ...
204 views

### Why are huge polygon amounts bad?

It is always said that the polygon amount of a single modell must be as little as possible when it comes to realtime simulations such as computer games. (Or at least lower than when rendering a movie) ...
171 views

### libgdx custom shape overlap detecting

I'm writing my game on libgdx w/o any of those extensions like box2d and whatsoever. But right now I'm forcing problem with overlapping detection. I need to detect if bullet (which is always in ...
246 views

### Calculate laser bounce inside polygon

I am trying to calculate the reflection of a laser within a polygon. My current calculations are probably quite long-winded because I'm building on line intersection and other functions. The problem ...
65 views

### Create Fog of war polygon obstacles

I'm doing a game (At this moment it's only a prototype using love2D) and I made a fog of war using a mesh over other things, and actually it's working, but I've got some assets (decoration for the ...
157 views

### How do I convert a partially transparent image into polygons?

I'm using GLEE2D, a level editor allowing me to import images, scale them, rotate them, and position them onto layers and export the data into XML format. However, it does not tell me objects' ...
89 views

### How can I test if a point is behind a polygon in 2D?

In order to improve the performance of my visibility graph generator I am trying to figure out the following. Given the image below; is there a way to find out if a point is 'behind' the polygon? For ...
414 views

### 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 ...
136 views

### Calculate mass moment of inertia of two 2D polygons

For a small 2D physics engine I need to know the following. I wasn't able to find an answer even after a week of research. Hope you can help me. I have multiple concave 2D polygons that are tight ...
1k views

### Polygons vs sprites rendering performance in Unity for windows phone 8

I'm currently building a windows phone 8 game with unity, having 111 (no more no less) sprites being updated each frames. I have a strong overhead in the profiler (70% to 90% minimum) I tried the ...
147 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 ...
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### 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?
636 views

### How can I drag a polygon based on a mouse-moved event?

I have drawn a polygon in Java using java.awt.Polygon. I want to move that polygon with the mouse (by dragging it). I know that I have to use mouseDragged method in addMouseMotionListener. That way I ...
197 views

### 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 ...
31 views

### Blendshapes workflow in mudbox

I am new to mudbox. I want to create a face with blendshapes. Currently my face has 24576 polygons on level 3. I would like to go to level 2 or level 1, ie lower than 6000, but there, detail suffers. ...
137 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 ...
188 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 ...
597 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 ...
450 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 ...
337 views

### Collision detection with multiple polygons simultaneously

I've written a collision system which detects/resolves collisions between a rectangular player and a convex polygon world using the Separating Axis Theorem. This scheme works fine when the player is ...
235 views

### Subdividing a polygon into boxes of varying size

I would like to be pointed to information / resources for creating algorithms like the one illustrated on this blog, which is a subdivision of a polygon (in my case a voronoi cell) into several boxes ...
83 views

### 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 ...
298 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 ...
724 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 ...
205 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 ...
104 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 ...
192 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 ...
199 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 ...
455 views

### 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 ...
1k 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; ...
4k 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 ...
395 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 ...
125 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 ...
732 views

### Moving CW or CCW?

Lets say we have a jagged shape: And two creatures moving along it's outline. Then we smooth the shape completely by pulling the corners out. We get this: It is easy to see now that Orange is ...
170 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 ...
277 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 ...
164 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 ...
277 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? ...
6k views

### How do I make a circular hole inside an editable poly without boolean operations?

I have created a rectangle, then converted it into an editable poly. Then I created a circle and converted it to editable poly too. How to make it so that that the circle becomes a hole in the ...
331 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: ...
572 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 ...
2k 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 ...
449 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 ...
1k views

### Can a straight line be called a polygon?

According to the definition of Polygon, If a Poly-line's first and last points are connected then it is called Polygon. See the image below. I have P1, .... P5 Polyline. If I draw a line from P5 to ...