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# deftware

Member Since 19 Oct 2005
Offline Last Active Jul 29 2015 04:16 PM

### finding delta quaternion to get from quat 'A' to quat 'B'

12 March 2015 - 02:13 AM

Hello gamedev enthusiasts..

I'm working on trying to find a quaternion I can use that is a fraction of the difference between a starting quaternion, 'A', and a destination quaternion 'B'.

I am not trying to simply interpolate from 'A' to 'B', but thought that if I could get 'B'-'A' and scale it by some fraction, I could effectively multiply 'A' by this fractional quaternion (which is actually what I need to be able to do) until it gets to 'B'. Meanwhile, there could be other forces affecting the quaternion, but I need the delta from 'A' to 'B' to be compounded with that rotation along with other forces. So a simple slerp will not suffice.

and it sounds good, but I am curious if anybody with a bit more know-how or experience can tell me that simply finding the difference and scaling it down (and re-normalizing it, I imagine) will be usable to just multiple 'A' against in succession to produce the same effect as slerping from 'A' to 'B'. Mind you, 'B' is not the destination, just a transient goal that affects a rotational momentum upon a quaternion that is only momentarily at 'A'.

### cost of rendering 'modular' entity models

19 October 2014 - 05:35 PM

Hi everyone.

I'm working on a problem where players can 'design' their player avatars by effectively choosing different limb models to be animated via skeletal animation type system. These limb models are not meant to be seamless. I'm curious as to whether or not there is any way I can draw these modular player models more efficiently without having to perform a draw call for each of these model pieces as well as submit a modelview matrix for each one. Each player model is comprised of 10 of these model pieces, which are extremely cheap as far as shaders and geometry is concerned.

Any ideas? Suggestions? One idea is to generate a VBO for each possible combination of pieces, but this just seems very extreme if I were to have 5 possible model types for each player model segment (5^10th = 9.7 million combinations).

EDIT: I am targeting OpenGL 3.3, just FYI

### generating branching structures without recursion

28 September 2014 - 07:13 PM

I thought I had this figured out, but now I'm starting to believe that I was mistaken. I'm working on generating simple branching structures (trees, basically) using a simple command scripting language that supports looping, but not recursion. There is also a stack that I can use the push/pop commands to save the current branch state and load it back to continue working from.

I'm very limited with what I can do with this scripting system, and for some reason I thought I had this figured out, but apparently I don't. Either I can't remember what I thought of, or what I thought of was totally wrong. My original 'aha' solution involved using two nested loops, and I keep thinking I had some clever use of the push/pop orientation stack that let the loops properly generate branches on branches to a defined depth, but I just can't remember or see what I was going to do.

Is it even possible? Am I just going mad?

### detecting 3D array configurations

04 June 2014 - 11:43 AM

Hi all.

I've been wracking my brain trying to find a simple solution to this problem, but everything I come up with seems overly complicated.

I have a 2x2x2 array where each cell can be on or off. This yields 256 possible states for the array. The problem I'm having is finding a way to detect a specific set of configurations - including their multiple possible orientations AND mirrored versions - without having to resort to creating a look up table. There are no requirements that disallow a simple look up table to determine which configuration the cells are in, except that I'd rather have a solution that could be expanded to larger arrays.

The closest to a solution I've devised thus far involves counting how many adjacent cells (eg: 0, 0, 0 - 1, 0, 0), diagonal cells (0, 0, 0 - 1, 1, 0) and opposing cells (0, 0, 0 - 1, 1, 1) there are, and comparing those numbers to the numbers involved in each configuration. This overcomes checking for various orientations and mirrored versions of specific cell configurations, but requires that cells are all manually inspected and compared against other cells, which seems unavoidable, but I keep getting this nagging feeling that I could somehow represent the array in a way that allows for an XOR or two against template configurations to count these relationships more quickly.

This is a very abstract problem without a clear and concise method of solving it. I've tried looking at it from many different angles and have exhausted myself for the time being. I'm merely seeking any insight anybody may have about an effective and efficient solution beyond what I have come up with on my own so far.

Thanks.

### Perfectionism and Programmer's Block

12 May 2014 - 04:44 PM

Hi there. I wanted to query the collective knowledge and experience of those who haunt these forums in an effort to find relief from something I can only describe as programmer's block.

I know what I want to make, but the knowledge about programming I've gained the past few years have only made it harder to get anything done without trying to do it 'right'. For some reason, doing it 'right' is taking precedent over getting it done. It becomes more of a chore, and less of a fun hobby.

Just getting into OpenGL 3+ has become a daunting task, trying to implement a highly versatile rendering system capable of everything I can't forsee.

That's just the issue though, the sense that I always code myself into a corner with projects, which has instilled a deep need to do everything as generalized, modular, and data-driven as possible. I feel I have taken certain programming tenets to extremes, yielding to nothing.

I have heard things such as YAGNI (you aren't gonna need it) and KISS (keep it simple stupid) and I'm still struggling. How do I surrender!? What should I focus on. I just want to switch off this awareness I have gained, or at least tone it down, to where I can actually knock stuff out and enjoy doing it.

Has anybody else struggled with knowing too much to be productive? I'm paralyzed!

Thanks

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