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Questions tagged [clipping]

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Clipping triangle normal direction

Trying to comprehend clipping algorithm given by ...
Pyrettt Pyrettt's user avatar
0 votes
1 answer
141 views

Triangle Rasterization Shaking Issues

I am making a Software renderer, and I noticed that there is a screen shaking like effect happening. shown in the first video: I tried doing filling without clipping against the small square, and the ...
Serilena's user avatar
0 votes
1 answer
91 views

My projection matrix for OpenGL fails on non-symmetric boundaries

Assuming my viewing volume has x coordinates varies from l to r, and y varies from top to bottom, and finally z-axis varies n to f, I derived the following projection matrix: ...
Serilena's user avatar
1 vote
1 answer
275 views

OpenGL layered rendering with multiple additional clip planes per view

I want to render a scene from multiple positions and orientations. I think the geometry shader is a good choice to not use the Vertex and tessellation shaders for each camera position again. So I want ...
Thomas's user avatar
  • 1,366
1 vote
1 answer
587 views

Rendering a volume that might be completely clipped in OpenGL

Suppose that I have some world-space volume (which we may assume is a convex polyhedron with a small number of vertices), and I want to render its intersection with the view frustum, such that every ...
lisyarus's user avatar
  • 225
4 votes
1 answer
373 views

How to interpolate vertices when clipping?

When we clip in homogeneous clip space, we have to generate a new vertex located at the intersection between the edge and the clip plane. We thus have to interpolate the $(x , y, z , w)$ position of ...
Voko's user avatar
  • 279
1 vote
1 answer
151 views

Using original vertices coordinates after clipping

Clipping is down in homogeneous clip space, therefore after multiplying the vertices by the model-view matrix. But as we do clipping in clip space, the position of the new vertices that we interpolate ...
Voko's user avatar
  • 279
1 vote
0 answers
137 views

Clipping 3D Perspective matrix

I am trying to implement clipping in my simple renderer, but i have a trouble with setting the boundaries. I used the same projection matrix that is in OpenGL. The problem is, the vertices that are ...
traksatov123's user avatar
3 votes
1 answer
471 views

3D coordinates of intersection point in clipping for a rasterizer

When doing clipping in homogeneous coordinates, we need to find the coordinates of the intersection of the viewing frustum with the line to be clipped. This can be done easily if we want those ...
Andreas's user avatar
  • 39
2 votes
1 answer
69 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 ...
user9778's user avatar
  • 201
10 votes
2 answers
6k 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://...
Jessy's user avatar
  • 203
1 vote
0 answers
142 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 |...
3D clipping.'s user avatar
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0 answers
317 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 < ...
Manh Nguyen Huu's user avatar
4 votes
1 answer
882 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. ...
chaosink's user avatar
  • 591
2 votes
3 answers
652 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 ...
Jonas Mechtheim's user avatar
2 votes
3 answers
685 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 ...
user3453636's user avatar
0 votes
1 answer
291 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 ...
user3453636's user avatar
6 votes
2 answers
2k 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?
Nolan's user avatar
  • 163
9 votes
1 answer
255 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 ...
user7413's user avatar
  • 143
1 vote
0 answers
229 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 ...
mrkotfw's user avatar
  • 11
4 votes
1 answer
2k 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 ...
user3263736's user avatar
3 votes
1 answer
739 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 ...
donutboy's user avatar
  • 143
3 votes
1 answer
1k 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. ...
roob's user avatar
  • 131
2 votes
1 answer
145 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 ...
zfb's user avatar
  • 145
3 votes
1 answer
318 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. ...
Nick's user avatar
  • 321
3 votes
1 answer
345 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 ...
Alex's user avatar
  • 163
4 votes
1 answer
275 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, ...
TheRapture87's user avatar
4 votes
1 answer
594 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 ...
gnzlbg's user avatar
  • 141
5 votes
2 answers
2k 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 ...
joojaa's user avatar
  • 8,457
8 votes
1 answer
1k 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 ...
Matthias's user avatar
  • 1,084
2 votes
1 answer
825 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 ?
john john's user avatar
  • 423
4 votes
1 answer
117 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, ...
JORGE's user avatar
  • 261
10 votes
0 answers
173 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. ...
luser droog's user avatar
  • 1,378