# Tag Info

6

The subdivision schemes are not arbitrary. Catmull-Clark, arguably the most used subdivision scheme, generalizes bicubic B-splines to meshes of arbitrary topology. Most, other subdivision schemes also generalize other degree B-splines to arbitrary topology. Doo-Sabin for biquadratic B-splines and Loop subdivision generalizes quartic box-splines defined ...

4

One algorithm that's pretty good for this, but very difficult to implement is to find the Medial Axis of the shape and then have various profiles that are based on the signed distance from the medial axis. You can also use the Straight Skeleton instead of the Medial Axis, but it's also a bit of a pain to calculate. An easier way that's not quite as accurate,...

4

In the painter's algorithm, you first sort all graphics elements on depth (deepest first) and then one-by-one fully paint them into the image on top of each other. That way, deeper elements are obscured by less deep element. (Intersecting graphics element require special attention.) In the depth-buffering algorithm, you store the current depth of each pixel ...

3

I would like to add that Painters' algorithm can be run from front to back with transparency provided your blending operations are associative. I would recommend reading Jim Blinn's "Compositing, Part 1: Theory". (Indeed, reading anything graphics related by Jim Blinn is highly recommended). In this article, Blinn explains (amongst their other advantages) ...

2

It depends a little on your actual data structure and how it even encodes boundary edges. What I find more useful than representing the boundary with a null half edge pointer, and thus having this situation of a half edge without an opposite and thus a hard stop for any such iteration, is instead encoding the boundary with a full half edge pair too, but with ...

2

An interesting problem. I've done a bit of work in texture compression and this sounds something like a generalisation of Campbell et al's "Color Cell Compression". It's also a little like a feature we were asked to include in the Dreamcast VQ compressor so that sub-palettes could be swapped to create different colour schemes on textures. I was thus ...

2

Like Rahul said that algorithm is only in the case where $0 \lt \Delta y \lt \Delta x$. So you need to adjust the coordinates to fit within that. There are 8 cases: $0 \lt \Delta y \lt \Delta x$ the normal base case $0 \lt \Delta x \lt \Delta y$ swap x and y except for the drawPixel call. $\Delta x \lt 0 \lt \Delta y$ and $|\Delta y < \Delta x|$ use ...

2

Yes, there is a fairly general algorithm to calculate this scaling factor, which works for all shapes with a known parametric representation. First, substitute the parametric equation of the shape (e.g. a torus, cylinder or cone) into the implicit equation of the sphere, $x^2 + y^2 + z^2 = S^2$. Then, solve this equation for the radius of the sphere. The ...

1

Given an intersection algorithm like the one you linked which first generates a $t$ value for every plane of the AABB, then computes $t_{min}$ and $t_{max}$ from those, you simply need to figure out which of the six initial values correspond to your final $t_{min}$. There will be two matches if your ray hits an edge, three if it hits a corner. In that case, ...

1

You could try the FiberMesh technique. Fibermesh takes 3D input curves and interprets them as the contours of the surface. It then creates a smooth surface by using an optimization technique. Here you can see a video, which demonstrates the technique.

1

The straightforward solution is to simple not render the high poly model at all. Have a lower detail model that you can switch to once the model is too far away for it to make a difference. There is no point in rendering 20 triangles that all end up in the same pixel. Next option is to partition the model and then cull the individual parts. You can also ...

1

The problem you are seeing, i.e. "jaggies" or "staircasing", is an example of the more general problem known as "aliasing" and, in the graphics field, the term you want to search for is "Antialiasing". Aliasing occurs when you undersample a signal. If a signal contains frequencies at or above the Nyquist Frequency, which is 1/2 the sampling frequency, ...

1

This seems to be eluding to a Marching Cubes LOD algorithm such as: Place the entire volume in one giant cube. Break that volume into NxNxN cubes. And continue doing so until the cubes are at the finest granularity needed for the density function about 8 level works. Each volume then responds with either: No voxels - stop processing that sub volume OR Yes ...

1

Perlin noise not good for real planet surface because planet surface is not random. Planet structure is create by geology/physics and interaction between different parts. This video show geology simulator have name PlaTec (have link in text below video): https://www.youtube.com/watch?v=bi4b45tMEPE Link have source code at SourceForge web site too.

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