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# Catmull Dog

Member Since 03 Aug 2012
Offline Last Active Sep 20 2012 09:07 AM

### In Topic: Finding the Slope of a giving Vertex in HLSL

11 September 2012 - 09:54 AM

The slope is the difference between two adjacent vertices. You probably want the point normal though, or the weighted, normalized average of all adjacent edges at a given vertex.

### In Topic: Algorithm for "grabbing" a Bezier spline/cubic Bezier curve

11 September 2012 - 08:02 AM

Ideally you will draw the control points and let the user drag them independently. To move the whole curve the user would type Ctrl-A to select All and then could drag any point to move the whole curve.

You may prefer Catmull Rom splines as they feature control points that lie on the curve (just the span 1 to 2), where Bezier defines a control polygon and only the endpoints 0 and 3 are on the curve). You can convert between them with a formula that is not too bad (see Figure4).

### In Topic: finding the closest distance of point to a line

10 September 2012 - 12:06 PM

Here is a good explanation of the 3D point to line problem.

The line connecting the point to the closest point meets the line at a right angle.

http://mathworld.wolfram.com/Point-LineDistance3-Dimensional.html

### In Topic: Stuck in late development

07 September 2012 - 08:25 AM

If any bugs can delay the shipping of a product, they will.

- Murphy's Law of Programming

### In Topic: Geologically Accurate Video Games

06 September 2012 - 03:17 PM

Sounds like the OP would enjoy the Seismic Exploration field in the Upstream Oil industry. Lots of 3d graphics these days.

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