# Questions tagged [polygon]

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17 questions with no upvoted or accepted answers
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### How to describe the bi-directional links for the Weiler-Atherton algorithm?

My postscript interpreter currently implements the Hodgeman-Sutherland clipping algorithm but this is limited to simpler shapes and doesn't have a provision for utilizing various winding-number rules. ...
• 1,343
158 views

### Generate polygons after marching squares in parallel

I've implemented the marching squares algorithm following Wikipedia's https://en.wikipedia.org/wiki/Marching_squares. The output I got is a set of edges, to which each contouring cell contributes 0, 1,...
• 31
86 views

### What is a good algorithm, and framework, to calculate centres of gravity or mass (cog)?

I'd like to take an photograph, subdivide it into a tesselation, either of squares, or (ideally), hexagons, and then find the centre of gravity (or, if you prefer, centre of mass) of each cell of the ...
• 131
54 views

### Divide mesh according to level of detail

Background I need to remesh by OpenVDB, like what Blender remesh does: Voxel Uses an OpenVDB to generate a new manifold mesh from the current geometry while trying to preserve the mesh’s original ...
• 133
1k views

### Scan Line Polygon Fill Edge Table Entry Order

I am trying to figure out the correct order between edges on edge table on scan line polygon fill. One example here on Y=1 takes first ...
• 121
1 vote
36 views

### How to get a polyline from an image with consistent winding number

I am trying to find an algorithm for the following problem. Assume we have a black and white image. The image contains a white region that encloses a space. This space may be concave but it has no ...
• 1,696
1 vote
54 views

### The ploygon width parallel to the x axis as a function of the y ordonate?

Considering a polygon with n vertices as input. I need to calculate the integral of the form $\int_A p(y) dA$ where $p(y)$ is a piecewise polynomial function of $y$. May be if I could find the ...
1 vote
141 views

### How to do a scanline fill with a self intersecting polygon?

I have a bezier curve and would like to draw it's stroke. To do that, I planned to approximate the stroke to a polygon and fill it with a scanline algorithm. While I feel confident about implementing ...
• 111
1 vote
56 views

### Convert a polygon mesh to a bspline surface

Problem: Getting a polygon mesh as input, I have to construct a surface that looks exactly to the given input. My task is to generate a b-spline surface that exactly looks like the connected polygon ...
• 131
1 vote
294 views

### How can I convert a shape made out of pixels to vertices

I'm trying to implement the solution to get the minimum dissection into rectangles of a rectilinear polygon. My shape is made out of pseudo-pixels (different width/height) but for the moment let's ...
• 183
1 vote
175 views

### Convert triangulated object to a polygonized object

Is there an efficient algorithm to convert a 3D object described with a set of triangles to a 3D object described with a set of polygons. Polygons can have an arbitrary number of points, more is ...
• 111
60 views

### Can STEP files contain polygon data? How do I get a smoother mesh out of a STEP file?

I am trying to work with a .STEP file I have received. Upon opening it in CAD Assistant, I find its surface as jagged lines, like a low poly model. When I export it as OBJ from there, the edges and ...
35 views

### AMD GPU specific triangles disappearing by subsequent draw calls in same frame

we have a Windows/DirectX11 2D Renderer that paints textured triangles to the screen from back to front. There is no face-culling or depth test activated. Now on AMD GPUs it happens randomly that an ...
63 views

### How would you represent a mesh with tris and quads?

My understanding is that, while subdivision algorithms like Catmull-Clark can work for any polygonal mesh (including triangles) it's preferable to start with a quad mesh. Currently my rendering engine ...
• 229
19 views

### Turning layered curves to polygon mesh?

I am confronted with the problem to render 3D representations for objects marked on microscope slices. So I have a set of aligned polygons in parallel planes from tracing the outline of the object in ...
• 141
45 views

### Cover a polygon with least amount of parallelograms

I am solving the task that is as follows: Input: a polygon. Can be any kind of polygon without self intersections. Can be a non-convex and with holes inside. Goal: to cover it with 2 (at least) or ...
• 101