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Questions tagged [clipping]

The tag has no usage guidance.

-1
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0answers
35 views

what is the limit of Triangulation Matting?

I am studying triangulation matting in computer graphic. It seems very simple but very cool to identify the foregrouand and background. However, I didn't find what's the limit of it. Besides the ...
2
votes
1answer
20 views

What are the outcodes that would be assigned to these points?

In Cohen-Sutherland clipping, it assigns outcodes to the points on lines that are drawn to specify their orientation relative to the clipping window. In the diagram below, I'm confused on what ...
7
votes
2answers
414 views

Why do GPUs divide clip space Z by W, for position?

Background: I found that it is very easy to use a linear depth buffer, using only a slight modification to the canonical vertex transformation. The simplest method is found at the bottom of https://...
1
vote
0answers
49 views

How to do clipping in 3D?

I have a list of vertices, I want to clip these inside the view frustum. Here's what I am planning to do : First I will loop through my list and check vertex $v$ for $|v.x| \le |v.w|$, $|v.y| \le |...
1
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0answers
71 views

How to do clipping in camera space?

I don't even know where to start. So far, the only progress I have gotten is checking the z value of each vertex of each triangle. If all three vertices' z values > absolute value of far or < ...
3
votes
1answer
218 views

Clipping for perspective projection

In the following two graphs, the red lines are borders of the perspective-projection frustum, the blue lines are to be rasterized, the green lines are perspective-projection lines, which are wrong. ...
3
votes
3answers
143 views

Fast clipping without clearing stencil buffer

I'm writing an OpenGL application that runs on a Raspberry Pi, i.e., a quite resource-limited system. Essentially, a few quads with RGBA textures are overlayed/alpha blended on top of each other with ...
3
votes
2answers
181 views

Clipping circle and polygon and generate a CAD drawing

I'm developing a CAD drawing generator using C# and netdxf library (https://github.com/haplokuon/netDxf) The app first performs boolean operations (specifically - union & subtraction) on polygons ...
1
vote
1answer
67 views

Finding vertices of the outer contour of intersecting polygons

I have a bunch of intersecting convex polygons, I want to find vertices of the outer contour of all those polygons. An individual polygon is not self-intersecting. Could you please tell What could be ...
5
votes
2answers
478 views

Why does opengl perform clipping in clip coordinates?

Is there any reason why OpenGL performs primitives' clipping in clip coordinates? Can it be at least theoretically done in normalized device coordinates?
8
votes
1answer
114 views

How can I check if a polygon can completely contain a circle of a certain radius?

How can I check if a polygon (can also be irregular) can completely contain a circle of a certain radius? I do not want to actually draw a circle inside the polygon but just a boolean outcome whether ...
1
vote
0answers
95 views

Algorithm for clipping convex quadrilaterals

I'm dealing with hardware that uses quads as its polygonal primitive. Not triangles. A triangle can be expressed by setting 2 of the 4 vertices equal to each other for a degenerate quad. For the 3D ...
5
votes
1answer
722 views

Worst Case Scenario for Cohen-Sutherland Line Clipping Algorithm

I'm currently enrolled in an entry level Computer Graphics class, and as I'm studying for my final, I realize I have a question regarding the Cohen-Sutherland line clipping algorithm. I understand the ...
4
votes
1answer
301 views

Why should you do homogenization after clipping?

Is it just so you avoid unnecessary divisions or are there other advantages as well? I've just implemented the Sutherland–Hodgman clipping algorithm and read online that you should do homogenization ...
2
votes
1answer
452 views

How to clip multiple tiled textures to polygon in Webgl / opengl

I have a bunch of planes each with their own texture in a grid. Currently I am rendering these as separate planes, each with their own texture, although I could use a single plane with multiple faces. ...
2
votes
1answer
96 views

Alternatives to Clipping in avoiding display problem

I know in computer graphic, we can set a world window in world coordinate system, and then mapping it to viewport which is the display window. Things that are not in the world window should not be ...
4
votes
1answer
131 views

Meaning of the parameter in a line-plane intersection in the space

The scenery is the following: I have a polygon in the space, defined (the polygon) from your vertices. By 3 vertices of the polygon (non-aligned) revenue equation of the plane containing the polygon. ...
5
votes
1answer
144 views

Maximal and minimal no. of angles obtained from clipping a convex polygon with n angles

I'm trying to figure this out for my Computer Graphics course, but I find it very hard to understand. I believe the minimum number of angles obtained from clipping a convex polygon with n angles is ...
4
votes
1answer
158 views

Cohen-Sutherland Clipping

Specify individually the translation and scaling matrices required to transform a 2D window of [Xmin=-234, Ymin=156] and [Xmax=66, Ymax=456] to a display viewport of [Umin=45, Vmin=35] and [Umax=245, ...
4
votes
1answer
297 views

Data structure and algorithm for clipping triangulation with leaf nodes of an octree

I have an application in which I am using an octree to store a volume mesh of axis-aligned bounding boxes (AABBs). Given a water-tight manifold triangle mesh, I need to: find if an AABB is ...
4
votes
2answers
403 views

Could we dispense the near clipping plane?

Would it be, at least theoretically, possible to render without a near clipping plane? Could raytracing ignore this perchance? Quite many budding 3d artists have a WTF moment the first time they ...
8
votes
1answer
459 views

Maximum number of vertices after clipping a triangle against an AABB

I clip a 3D triangle against a 3D Axis-Aligned Bounding Box (AABB) to obtain the largest planar polygon of the triangle contained in the AABB. My clipping algorithm is a (slightly modified) version of ...
1
vote
1answer
606 views

Outcodes in Cohen-Sutherland Clipping Algorithm

What advantages do the outcodes offer in this algorithm ? Do they help in simplifying the algorithm ? Do they decrease the number of calculations ?
4
votes
1answer
105 views

Parametric line intersection test

I have the following question in an exam review and I am looking for feedback about how to approach the solution. Any advice will be highly appreciated. "Using a parametric line intersection test, ...
9
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0answers
120 views

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. ...